Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

20 files changed, 22162 insertions, 0 deletions

diff --git a/src/backend/utils/misc/.gitignore b/src/backend/utils/misc/.gitignore
new file mode 100644
index 0000000..495b1ae
--- /dev/null
+++ b/src/backend/utils/misc/.gitignore
@@ -0,0 +1 @@
+/guc-file.c
diff --git a/src/backend/utils/misc/Makefile b/src/backend/utils/misc/Makefile
new file mode 100644
index 0000000..1d5327c
--- /dev/null
+++ b/src/backend/utils/misc/Makefile
@@ -0,0 +1,46 @@
+#-------------------------------------------------------------------------
+#
+# Makefile--
+#    Makefile for utils/misc
+#
+# IDENTIFICATION
+#    src/backend/utils/misc/Makefile
+#
+#-------------------------------------------------------------------------
+
+subdir = src/backend/utils/misc
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+
+override CPPFLAGS := -I. -I$(srcdir) $(CPPFLAGS)
+
+OBJS = \
+	guc.o \
+	help_config.o \
+	pg_config.o \
+	pg_controldata.o \
+	pg_rusage.o \
+	ps_status.o \
+	queryenvironment.o \
+	queryjumble.o \
+	rls.o \
+	sampling.o \
+	superuser.o \
+	timeout.o \
+	tzparser.o
+
+# This location might depend on the installation directories. Therefore
+# we can't substitute it into pg_config.h.
+ifdef krb_srvtab
+override CPPFLAGS += -DPG_KRB_SRVTAB='"$(krb_srvtab)"'
+endif
+
+include $(top_srcdir)/src/backend/common.mk
+
+# guc-file is compiled as part of guc
+guc.o: guc-file.c
+
+# Note: guc-file.c is not deleted by 'make clean',
+# since we want to ship it in distribution tarballs.
+clean:
+	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/README b/src/backend/utils/misc/README
new file mode 100644
index 0000000..6e29438
--- /dev/null
+++ b/src/backend/utils/misc/README
@@ -0,0 +1,295 @@
+src/backend/utils/misc/README
+
+GUC Implementation Notes
+========================
+
+The GUC (Grand Unified Configuration) module implements configuration
+variables of multiple types (currently boolean, enum, int, real, and string).
+Variable settings can come from various places, with a priority ordering
+determining which setting is used.
+
+
+Per-Variable Hooks
+------------------
+
+Each variable known to GUC can optionally have a check_hook, an
+assign_hook, and/or a show_hook to provide customized behavior.
+Check hooks are used to perform validity checking on variable values
+(above and beyond what GUC can do), to compute derived settings when
+nontrivial work is needed to do that, and optionally to "canonicalize"
+user-supplied values.  Assign hooks are used to update any derived state
+that needs to change when a GUC variable is set.  Show hooks are used to
+modify the default SHOW display for a variable.
+
+
+If a check_hook is provided, it points to a function of the signature
+	bool check_hook(datatype *newvalue, void **extra, GucSource source)
+The "newvalue" argument is of type bool *, int *, double *, or char **
+for bool, int/enum, real, or string variables respectively.  The check
+function should validate the proposed new value, and return true if it is
+OK or false if not.  The function can optionally do a few other things:
+
+* When rejecting a bad proposed value, it may be useful to append some
+additional information to the generic "invalid value for parameter FOO"
+complaint that guc.c will emit.  To do that, call
+	void GUC_check_errdetail(const char *format, ...)
+where the format string and additional arguments follow the rules for
+errdetail() arguments.  The resulting string will be emitted as the
+DETAIL line of guc.c's error report, so it should follow the message style
+guidelines for DETAIL messages.  There is also
+	void GUC_check_errhint(const char *format, ...)
+which can be used in the same way to append a HINT message.
+Occasionally it may even be appropriate to override guc.c's generic primary
+message or error code, which can be done with
+	void GUC_check_errcode(int sqlerrcode)
+	void GUC_check_errmsg(const char *format, ...)
+In general, check_hooks should avoid throwing errors directly if possible,
+though this may be impractical to avoid for some corner cases such as
+out-of-memory.
+
+* Since the newvalue is pass-by-reference, the function can modify it.
+This might be used for example to canonicalize the spelling of a string
+value, round off a buffer size to the nearest supported value, or replace
+a special value such as "-1" with a computed default value.  If the
+function wishes to replace a string value, it must malloc (not palloc)
+the replacement value, and be sure to free() the previous value.
+
+* Derived information, such as the role OID represented by a user name,
+can be stored for use by the assign hook.  To do this, malloc (not palloc)
+storage space for the information, and return its address at *extra.
+guc.c will automatically free() this space when the associated GUC setting
+is no longer of interest.  *extra is initialized to NULL before call, so
+it can be ignored if not needed.
+
+The "source" argument indicates the source of the proposed new value,
+If it is >= PGC_S_INTERACTIVE, then we are performing an interactive
+assignment (e.g., a SET command).  But when source < PGC_S_INTERACTIVE,
+we are reading a non-interactive option source, such as postgresql.conf.
+This is sometimes needed to determine whether a setting should be
+allowed.  The check_hook might also look at the current actual value of
+the variable to determine what is allowed.
+
+Note that check hooks are sometimes called just to validate a value,
+without any intention of actually changing the setting.  Therefore the
+check hook must *not* take any action based on the assumption that an
+assignment will occur.
+
+
+If an assign_hook is provided, it points to a function of the signature
+	void assign_hook(datatype newvalue, void *extra)
+where the type of "newvalue" matches the kind of variable, and "extra"
+is the derived-information pointer returned by the check_hook (always
+NULL if there is no check_hook).  This function is called immediately
+before actually setting the variable's value (so it can look at the actual
+variable to determine the old value, for example to avoid doing work when
+the value isn't really changing).
+
+Note that there is no provision for a failure result code.  assign_hooks
+should never fail except under the most dire circumstances, since a failure
+may for example result in GUC settings not being rolled back properly during
+transaction abort.  In general, try to do anything that could conceivably
+fail in a check_hook instead, and pass along the results in an "extra"
+struct, so that the assign hook has little to do beyond copying the data to
+someplace.  This applies particularly to catalog lookups: any required
+lookups must be done in the check_hook, since the assign_hook may be
+executed during transaction rollback when lookups will be unsafe.
+
+Note that check_hooks are sometimes called outside any transaction, too.
+This happens when processing the wired-in "bootstrap" value, values coming
+from the postmaster command line or environment, or values coming from
+postgresql.conf.  Therefore, any catalog lookups done in a check_hook
+should be guarded with an IsTransactionState() test, and there must be a
+fallback path to allow derived values to be computed during the first
+subsequent use of the GUC setting within a transaction.  A typical
+arrangement is for the catalog values computed by the check_hook and
+installed by the assign_hook to be used only for the remainder of the
+transaction in which the new setting is made.  Each subsequent transaction
+looks up the values afresh on first use.  This arrangement is useful to
+prevent use of stale catalog values, independently of the problem of
+needing to check GUC values outside a transaction.
+
+
+If a show_hook is provided, it points to a function of the signature
+	const char *show_hook(void)
+This hook allows variable-specific computation of the value displayed
+by SHOW (and other SQL features for showing GUC variable values).
+The return value can point to a static buffer, since show functions are
+not used reentrantly.
+
+
+Saving/Restoring GUC Variable Values
+------------------------------------
+
+Prior values of configuration variables must be remembered in order to deal
+with several special cases: RESET (a/k/a SET TO DEFAULT), rollback of SET
+on transaction abort, rollback of SET LOCAL at transaction end (either
+commit or abort), and save/restore around a function that has a SET option.
+RESET is defined as selecting the value that would be effective had there
+never been any SET commands in the current session.
+
+To handle these cases we must keep track of many distinct values for each
+variable.  The primary values are:
+
+* actual variable contents	always the current effective value
+
+* reset_val			the value to use for RESET
+
+(Each GUC entry also has a boot_val which is the wired-in default value.
+This is assigned to the reset_val and the actual variable during
+InitializeGUCOptions().  The boot_val is also consulted to restore the
+correct reset_val if SIGHUP processing discovers that a variable formerly
+specified in postgresql.conf is no longer set there.)
+
+In addition to the primary values, there is a stack of former effective
+values that might need to be restored in future.  Stacking and unstacking
+is controlled by the GUC "nest level", which is zero when outside any
+transaction, one at top transaction level, and incremented for each
+open subtransaction or function call with a SET option.  A stack entry
+is made whenever a GUC variable is first modified at a given nesting level.
+(Note: the reset_val need not be stacked because it is only changed by
+non-transactional operations.)
+
+A stack entry has a state, a prior value of the GUC variable, a remembered
+source of that prior value, and depending on the state may also have a
+"masked" value.  The masked value is needed when SET followed by SET LOCAL
+occur at the same nest level: the SET's value is masked but must be
+remembered to restore after transaction commit.
+
+During initialization we set the actual value and reset_val based on
+whichever non-interactive source has the highest priority.  They will
+have the same value.
+
+The possible transactional operations on a GUC value are:
+
+Entry to a function with a SET option:
+
+	Push a stack entry with the prior variable value and state SAVE,
+	then set the variable.
+
+Plain SET command:
+
+	If no stack entry of current level:
+		Push new stack entry w/prior value and state SET
+	else if stack entry's state is SAVE, SET, or LOCAL:
+		change stack state to SET, don't change saved value
+		(here we are forgetting effects of prior set action)
+	else (entry must have state SET+LOCAL):
+		discard its masked value, change state to SET
+		(here we are forgetting effects of prior SET and SET LOCAL)
+	Now set new value.
+
+SET LOCAL command:
+
+	If no stack entry of current level:
+		Push new stack entry w/prior value and state LOCAL
+	else if stack entry's state is SAVE or LOCAL or SET+LOCAL:
+		no change to stack entry
+		(in SAVE case, SET LOCAL will be forgotten at func exit)
+	else (entry must have state SET):
+		put current active into its masked slot, set state SET+LOCAL
+	Now set new value.
+
+Transaction or subtransaction abort:
+
+	Pop stack entries, restoring prior value, until top < subxact depth
+
+Transaction or subtransaction commit (incl. successful function exit):
+
+	While stack entry level >= subxact depth
+
+		if entry's state is SAVE:
+			pop, restoring prior value
+		else if level is 1 and entry's state is SET+LOCAL:
+			pop, restoring *masked* value
+		else if level is 1 and entry's state is SET:
+			pop, discarding old value
+		else if level is 1 and entry's state is LOCAL:
+			pop, restoring prior value
+		else if there is no entry of exactly level N-1:
+			decrement entry's level, no other state change
+		else
+			merge entries of level N-1 and N as specified below
+
+The merged entry will have level N-1 and prior = older prior, so easiest
+to keep older entry and free newer.  There are 12 possibilities since
+we already handled level N state = SAVE:
+
+N-1		N
+
+SAVE		SET		discard top prior, set state SET
+SAVE		LOCAL		discard top prior, no change to stack entry
+SAVE		SET+LOCAL	discard top prior, copy masked, state S+L
+
+SET		SET		discard top prior, no change to stack entry
+SET		LOCAL		copy top prior to masked, state S+L
+SET		SET+LOCAL	discard top prior, copy masked, state S+L
+
+LOCAL		SET		discard top prior, set state SET
+LOCAL		LOCAL		discard top prior, no change to stack entry
+LOCAL		SET+LOCAL	discard top prior, copy masked, state S+L
+
+SET+LOCAL	SET		discard top prior and second masked, state SET
+SET+LOCAL	LOCAL		discard top prior, no change to stack entry
+SET+LOCAL	SET+LOCAL	discard top prior, copy masked, state S+L
+
+
+RESET is executed like a SET, but using the reset_val as the desired new
+value.  (We do not provide a RESET LOCAL command, but SET LOCAL TO DEFAULT
+has the same behavior that RESET LOCAL would.)  The source associated with
+the reset_val also becomes associated with the actual value.
+
+If SIGHUP is received, the GUC code rereads the postgresql.conf
+configuration file (this does not happen in the signal handler, but at
+next return to main loop; note that it can be executed while within a
+transaction).  New values from postgresql.conf are assigned to actual
+variable, reset_val, and stacked actual values, but only if each of
+these has a current source priority <= PGC_S_FILE.  (It is thus possible
+for reset_val to track the config-file setting even if there is
+currently a different interactive value of the actual variable.)
+
+The check_hook, assign_hook and show_hook routines work only with the
+actual variable, and are not directly aware of the additional values
+maintained by GUC.
+
+
+GUC Memory Handling
+-------------------
+
+String variable values are allocated with malloc/strdup, not with the
+palloc/pstrdup mechanisms.  We would need to keep them in a permanent
+context anyway, and malloc gives us more control over handling
+out-of-memory failures.
+
+We allow a string variable's actual value, reset_val, boot_val, and stacked
+values to point at the same storage.  This makes it slightly harder to free
+space (we must test whether a value to be freed isn't equal to any of the
+other pointers in the GUC entry or associated stack items).  The main
+advantage is that we never need to malloc during transaction commit/abort,
+so cannot cause an out-of-memory failure there.
+
+"Extra" structs returned by check_hook routines are managed in the same
+way as string values.  Note that we support "extra" structs for all types
+of GUC variables, although they are mainly useful with strings.
+
+
+GUC and Null String Variables
+-----------------------------
+
+A GUC string variable can have a boot_val of NULL.  guc.c handles this
+unsurprisingly, assigning the NULL to the underlying C variable.  Any code
+using such a variable, as well as any hook functions for it, must then be
+prepared to deal with a NULL value.
+
+However, it is not possible to assign a NULL value to a GUC string
+variable in any other way: values coming from SET, postgresql.conf, etc,
+might be empty strings, but they'll never be NULL.  And SHOW displays
+a NULL the same as an empty string.  It is therefore not appropriate to
+treat a NULL value as a distinct user-visible setting.  A typical use
+for a NULL boot_val is to denote that a value hasn't yet been set for
+a variable that will receive a real value later in startup.
+
+If it's undesirable for code using the underlying C variable to have to
+worry about NULL values ever, the variable can be given a non-null static
+initializer as well as a non-null boot_val.  guc.c will overwrite the
+static initializer pointer with a copy of the boot_val during
+InitializeGUCOptions, but the variable will never contain a NULL.
diff --git a/src/backend/utils/misc/check_guc b/src/backend/utils/misc/check_guc
new file mode 100755
index 0000000..b171ef0
--- /dev/null
+++ b/src/backend/utils/misc/check_guc
@@ -0,0 +1,78 @@
+#!/bin/sh
+
+## currently, this script makes a lot of assumptions:
+## in postgresql.conf.sample:
+##   1) the valid config settings may be preceded by a '#', but NOT '# '
+##      (we use this to skip comments)
+##   2) the valid config settings will be followed immediately by  ' ='
+##      (at least one space preceding the '=')
+## in guc.c:
+##   3) the options have PGC_ on the same line as the option
+##   4) the options have '{' on the same line as the option
+
+##  Problems
+## 1) Don't know what to do with TRANSACTION ISOLATION LEVEL
+
+## if an option is valid but shows up in only one file (guc.c but not
+## postgresql.conf.sample), it should be listed here so that it
+## can be ignored
+INTENTIONALLY_NOT_INCLUDED="debug_deadlocks in_hot_standby \
+is_superuser lc_collate lc_ctype lc_messages lc_monetary lc_numeric lc_time \
+pre_auth_delay role seed server_encoding server_version server_version_num \
+session_authorization trace_lock_oidmin trace_lock_table trace_locks trace_lwlocks \
+trace_notify trace_userlocks transaction_isolation transaction_read_only \
+zero_damaged_pages"
+
+### What options are listed in postgresql.conf.sample, but don't appear
+### in guc.c?
+
+# grab everything that looks like a setting and convert it to lower case
+SETTINGS=`grep ' =' postgresql.conf.sample |
+grep -v '^# ' | # strip comments
+sed -e 's/^#//' |
+awk '{print $1}'`
+
+SETTINGS=`echo "$SETTINGS" | tr 'A-Z' 'a-z'`
+
+for i in $SETTINGS ; do
+  hidden=0
+  ## it sure would be nice to replace this with an sql "not in" statement
+  ## it doesn't seem to make sense to have things in .sample and not in guc.c
+#  for hidethis in $INTENTIONALLY_NOT_INCLUDED ; do
+#    if [ "$hidethis" = "$i" ] ; then
+#      hidden=1
+#    fi
+#  done
+  if [ "$hidden" -eq 0 ] ; then
+    grep -i '"'$i'"' guc.c > /dev/null
+    if [ $? -ne 0 ] ; then
+      echo "$i seems to be missing from guc.c";
+    fi;
+  fi
+done
+
+### What options are listed in guc.c, but don't appear
+### in postgresql.conf.sample?
+
+# grab everything that looks like a setting and convert it to lower case
+
+SETTINGS=`grep '{.* PGC_' guc.c | awk '{print $1}' | \
+          sed -e 's/{//g' -e 's/"//g' -e 's/,//'`
+
+SETTINGS=`echo "$SETTINGS" | tr 'A-Z' 'a-z'`
+
+for i in $SETTINGS ; do
+  hidden=0
+  ## it sure would be nice to replace this with an sql "not in" statement
+  for hidethis in $INTENTIONALLY_NOT_INCLUDED ; do
+    if [ "$hidethis" = "$i" ] ; then
+      hidden=1
+    fi
+  done
+  if [ "$hidden" -eq 0 ] ; then
+    grep -i '#'$i' ' postgresql.conf.sample > /dev/null
+    if [ $? -ne 0 ] ; then
+      echo "$i seems to be missing from postgresql.conf.sample";
+    fi
+  fi
+done
diff --git a/src/backend/utils/misc/guc-file.c b/src/backend/utils/misc/guc-file.c
new file mode 100644
index 0000000..f1acf30
--- /dev/null
+++ b/src/backend/utils/misc/guc-file.c
@@ -0,0 +1,3232 @@
+#line 2 "guc-file.c"
+
+#line 4 "guc-file.c"
+
+#define  YY_INT_ALIGNED short int
+
+/* A lexical scanner generated by flex */
+
+#define yy_create_buffer GUC_yy_create_buffer
+#define yy_delete_buffer GUC_yy_delete_buffer
+#define yy_scan_buffer GUC_yy_scan_buffer
+#define yy_scan_string GUC_yy_scan_string
+#define yy_scan_bytes GUC_yy_scan_bytes
+#define yy_init_buffer GUC_yy_init_buffer
+#define yy_flush_buffer GUC_yy_flush_buffer
+#define yy_load_buffer_state GUC_yy_load_buffer_state
+#define yy_switch_to_buffer GUC_yy_switch_to_buffer
+#define yypush_buffer_state GUC_yypush_buffer_state
+#define yypop_buffer_state GUC_yypop_buffer_state
+#define yyensure_buffer_stack GUC_yyensure_buffer_stack
+#define yy_flex_debug GUC_yy_flex_debug
+#define yyin GUC_yyin
+#define yyleng GUC_yyleng
+#define yylex GUC_yylex
+#define yylineno GUC_yylineno
+#define yyout GUC_yyout
+#define yyrestart GUC_yyrestart
+#define yytext GUC_yytext
+#define yywrap GUC_yywrap
+#define yyalloc GUC_yyalloc
+#define yyrealloc GUC_yyrealloc
+#define yyfree GUC_yyfree
+
+#define FLEX_SCANNER
+#define YY_FLEX_MAJOR_VERSION 2
+#define YY_FLEX_MINOR_VERSION 6
+#define YY_FLEX_SUBMINOR_VERSION 4
+#if YY_FLEX_SUBMINOR_VERSION > 0
+#define FLEX_BETA
+#endif
+
+#ifdef yy_create_buffer
+#define GUC_yy_create_buffer_ALREADY_DEFINED
+#else
+#define yy_create_buffer GUC_yy_create_buffer
+#endif
+
+#ifdef yy_delete_buffer
+#define GUC_yy_delete_buffer_ALREADY_DEFINED
+#else
+#define yy_delete_buffer GUC_yy_delete_buffer
+#endif
+
+#ifdef yy_scan_buffer
+#define GUC_yy_scan_buffer_ALREADY_DEFINED
+#else
+#define yy_scan_buffer GUC_yy_scan_buffer
+#endif
+
+#ifdef yy_scan_string
+#define GUC_yy_scan_string_ALREADY_DEFINED
+#else
+#define yy_scan_string GUC_yy_scan_string
+#endif
+
+#ifdef yy_scan_bytes
+#define GUC_yy_scan_bytes_ALREADY_DEFINED
+#else
+#define yy_scan_bytes GUC_yy_scan_bytes
+#endif
+
+#ifdef yy_init_buffer
+#define GUC_yy_init_buffer_ALREADY_DEFINED
+#else
+#define yy_init_buffer GUC_yy_init_buffer
+#endif
+
+#ifdef yy_flush_buffer
+#define GUC_yy_flush_buffer_ALREADY_DEFINED
+#else
+#define yy_flush_buffer GUC_yy_flush_buffer
+#endif
+
+#ifdef yy_load_buffer_state
+#define GUC_yy_load_buffer_state_ALREADY_DEFINED
+#else
+#define yy_load_buffer_state GUC_yy_load_buffer_state
+#endif
+
+#ifdef yy_switch_to_buffer
+#define GUC_yy_switch_to_buffer_ALREADY_DEFINED
+#else
+#define yy_switch_to_buffer GUC_yy_switch_to_buffer
+#endif
+
+#ifdef yypush_buffer_state
+#define GUC_yypush_buffer_state_ALREADY_DEFINED
+#else
+#define yypush_buffer_state GUC_yypush_buffer_state
+#endif
+
+#ifdef yypop_buffer_state
+#define GUC_yypop_buffer_state_ALREADY_DEFINED
+#else
+#define yypop_buffer_state GUC_yypop_buffer_state
+#endif
+
+#ifdef yyensure_buffer_stack
+#define GUC_yyensure_buffer_stack_ALREADY_DEFINED
+#else
+#define yyensure_buffer_stack GUC_yyensure_buffer_stack
+#endif
+
+#ifdef yylex
+#define GUC_yylex_ALREADY_DEFINED
+#else
+#define yylex GUC_yylex
+#endif
+
+#ifdef yyrestart
+#define GUC_yyrestart_ALREADY_DEFINED
+#else
+#define yyrestart GUC_yyrestart
+#endif
+
+#ifdef yylex_init
+#define GUC_yylex_init_ALREADY_DEFINED
+#else
+#define yylex_init GUC_yylex_init
+#endif
+
+#ifdef yylex_init_extra
+#define GUC_yylex_init_extra_ALREADY_DEFINED
+#else
+#define yylex_init_extra GUC_yylex_init_extra
+#endif
+
+#ifdef yylex_destroy
+#define GUC_yylex_destroy_ALREADY_DEFINED
+#else
+#define yylex_destroy GUC_yylex_destroy
+#endif
+
+#ifdef yyget_debug
+#define GUC_yyget_debug_ALREADY_DEFINED
+#else
+#define yyget_debug GUC_yyget_debug
+#endif
+
+#ifdef yyset_debug
+#define GUC_yyset_debug_ALREADY_DEFINED
+#else
+#define yyset_debug GUC_yyset_debug
+#endif
+
+#ifdef yyget_extra
+#define GUC_yyget_extra_ALREADY_DEFINED
+#else
+#define yyget_extra GUC_yyget_extra
+#endif
+
+#ifdef yyset_extra
+#define GUC_yyset_extra_ALREADY_DEFINED
+#else
+#define yyset_extra GUC_yyset_extra
+#endif
+
+#ifdef yyget_in
+#define GUC_yyget_in_ALREADY_DEFINED
+#else
+#define yyget_in GUC_yyget_in
+#endif
+
+#ifdef yyset_in
+#define GUC_yyset_in_ALREADY_DEFINED
+#else
+#define yyset_in GUC_yyset_in
+#endif
+
+#ifdef yyget_out
+#define GUC_yyget_out_ALREADY_DEFINED
+#else
+#define yyget_out GUC_yyget_out
+#endif
+
+#ifdef yyset_out
+#define GUC_yyset_out_ALREADY_DEFINED
+#else
+#define yyset_out GUC_yyset_out
+#endif
+
+#ifdef yyget_leng
+#define GUC_yyget_leng_ALREADY_DEFINED
+#else
+#define yyget_leng GUC_yyget_leng
+#endif
+
+#ifdef yyget_text
+#define GUC_yyget_text_ALREADY_DEFINED
+#else
+#define yyget_text GUC_yyget_text
+#endif
+
+#ifdef yyget_lineno
+#define GUC_yyget_lineno_ALREADY_DEFINED
+#else
+#define yyget_lineno GUC_yyget_lineno
+#endif
+
+#ifdef yyset_lineno
+#define GUC_yyset_lineno_ALREADY_DEFINED
+#else
+#define yyset_lineno GUC_yyset_lineno
+#endif
+
+#ifdef yywrap
+#define GUC_yywrap_ALREADY_DEFINED
+#else
+#define yywrap GUC_yywrap
+#endif
+
+#ifdef yyalloc
+#define GUC_yyalloc_ALREADY_DEFINED
+#else
+#define yyalloc GUC_yyalloc
+#endif
+
+#ifdef yyrealloc
+#define GUC_yyrealloc_ALREADY_DEFINED
+#else
+#define yyrealloc GUC_yyrealloc
+#endif
+
+#ifdef yyfree
+#define GUC_yyfree_ALREADY_DEFINED
+#else
+#define yyfree GUC_yyfree
+#endif
+
+#ifdef yytext
+#define GUC_yytext_ALREADY_DEFINED
+#else
+#define yytext GUC_yytext
+#endif
+
+#ifdef yyleng
+#define GUC_yyleng_ALREADY_DEFINED
+#else
+#define yyleng GUC_yyleng
+#endif
+
+#ifdef yyin
+#define GUC_yyin_ALREADY_DEFINED
+#else
+#define yyin GUC_yyin
+#endif
+
+#ifdef yyout
+#define GUC_yyout_ALREADY_DEFINED
+#else
+#define yyout GUC_yyout
+#endif
+
+#ifdef yy_flex_debug
+#define GUC_yy_flex_debug_ALREADY_DEFINED
+#else
+#define yy_flex_debug GUC_yy_flex_debug
+#endif
+
+#ifdef yylineno
+#define GUC_yylineno_ALREADY_DEFINED
+#else
+#define yylineno GUC_yylineno
+#endif
+
+/* First, we deal with  platform-specific or compiler-specific issues. */
+
+/* begin standard C headers. */
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+
+/* end standard C headers. */
+
+/* flex integer type definitions */
+
+#ifndef FLEXINT_H
+#define FLEXINT_H
+
+/* C99 systems have <inttypes.h>. Non-C99 systems may or may not. */
+
+#if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+
+/* C99 says to define __STDC_LIMIT_MACROS before including stdint.h,
+ * if you want the limit (max/min) macros for int types. 
+ */
+#ifndef __STDC_LIMIT_MACROS
+#define __STDC_LIMIT_MACROS 1
+#endif
+
+#include <inttypes.h>
+typedef int8_t flex_int8_t;
+typedef uint8_t flex_uint8_t;
+typedef int16_t flex_int16_t;
+typedef uint16_t flex_uint16_t;
+typedef int32_t flex_int32_t;
+typedef uint32_t flex_uint32_t;
+#else
+typedef signed char flex_int8_t;
+typedef short int flex_int16_t;
+typedef int flex_int32_t;
+typedef unsigned char flex_uint8_t; 
+typedef unsigned short int flex_uint16_t;
+typedef unsigned int flex_uint32_t;
+
+/* Limits of integral types. */
+#ifndef INT8_MIN
+#define INT8_MIN               (-128)
+#endif
+#ifndef INT16_MIN
+#define INT16_MIN              (-32767-1)
+#endif
+#ifndef INT32_MIN
+#define INT32_MIN              (-2147483647-1)
+#endif
+#ifndef INT8_MAX
+#define INT8_MAX               (127)
+#endif
+#ifndef INT16_MAX
+#define INT16_MAX              (32767)
+#endif
+#ifndef INT32_MAX
+#define INT32_MAX              (2147483647)
+#endif
+#ifndef UINT8_MAX
+#define UINT8_MAX              (255U)
+#endif
+#ifndef UINT16_MAX
+#define UINT16_MAX             (65535U)
+#endif
+#ifndef UINT32_MAX
+#define UINT32_MAX             (4294967295U)
+#endif
+
+#ifndef SIZE_MAX
+#define SIZE_MAX               (~(size_t)0)
+#endif
+
+#endif /* ! C99 */
+
+#endif /* ! FLEXINT_H */
+
+/* begin standard C++ headers. */
+
+/* TODO: this is always defined, so inline it */
+#define yyconst const
+
+#if defined(__GNUC__) && __GNUC__ >= 3
+#define yynoreturn __attribute__((__noreturn__))
+#else
+#define yynoreturn
+#endif
+
+/* Returned upon end-of-file. */
+#define YY_NULL 0
+
+/* Promotes a possibly negative, possibly signed char to an
+ *   integer in range [0..255] for use as an array index.
+ */
+#define YY_SC_TO_UI(c) ((YY_CHAR) (c))
+
+/* Enter a start condition.  This macro really ought to take a parameter,
+ * but we do it the disgusting crufty way forced on us by the ()-less
+ * definition of BEGIN.
+ */
+#define BEGIN (yy_start) = 1 + 2 *
+/* Translate the current start state into a value that can be later handed
+ * to BEGIN to return to the state.  The YYSTATE alias is for lex
+ * compatibility.
+ */
+#define YY_START (((yy_start) - 1) / 2)
+#define YYSTATE YY_START
+/* Action number for EOF rule of a given start state. */
+#define YY_STATE_EOF(state) (YY_END_OF_BUFFER + state + 1)
+/* Special action meaning "start processing a new file". */
+#define YY_NEW_FILE yyrestart( yyin  )
+#define YY_END_OF_BUFFER_CHAR 0
+
+/* Size of default input buffer. */
+#ifndef YY_BUF_SIZE
+#ifdef __ia64__
+/* On IA-64, the buffer size is 16k, not 8k.
+ * Moreover, YY_BUF_SIZE is 2*YY_READ_BUF_SIZE in the general case.
+ * Ditto for the __ia64__ case accordingly.
+ */
+#define YY_BUF_SIZE 32768
+#else
+#define YY_BUF_SIZE 16384
+#endif /* __ia64__ */
+#endif
+
+/* The state buf must be large enough to hold one state per character in the main buffer.
+ */
+#define YY_STATE_BUF_SIZE   ((YY_BUF_SIZE + 2) * sizeof(yy_state_type))
+
+#ifndef YY_TYPEDEF_YY_BUFFER_STATE
+#define YY_TYPEDEF_YY_BUFFER_STATE
+typedef struct yy_buffer_state *YY_BUFFER_STATE;
+#endif
+
+#ifndef YY_TYPEDEF_YY_SIZE_T
+#define YY_TYPEDEF_YY_SIZE_T
+typedef size_t yy_size_t;
+#endif
+
+extern int yyleng;
+
+extern FILE *yyin, *yyout;
+
+#define EOB_ACT_CONTINUE_SCAN 0
+#define EOB_ACT_END_OF_FILE 1
+#define EOB_ACT_LAST_MATCH 2
+    
+    #define YY_LESS_LINENO(n)
+    #define YY_LINENO_REWIND_TO(ptr)
+    
+/* Return all but the first "n" matched characters back to the input stream. */
+#define yyless(n) \
+	do \
+		{ \
+		/* Undo effects of setting up yytext. */ \
+        int yyless_macro_arg = (n); \
+        YY_LESS_LINENO(yyless_macro_arg);\
+		*yy_cp = (yy_hold_char); \
+		YY_RESTORE_YY_MORE_OFFSET \
+		(yy_c_buf_p) = yy_cp = yy_bp + yyless_macro_arg - YY_MORE_ADJ; \
+		YY_DO_BEFORE_ACTION; /* set up yytext again */ \
+		} \
+	while ( 0 )
+#define unput(c) yyunput( c, (yytext_ptr)  )
+
+#ifndef YY_STRUCT_YY_BUFFER_STATE
+#define YY_STRUCT_YY_BUFFER_STATE
+struct yy_buffer_state
+	{
+	FILE *yy_input_file;
+
+	char *yy_ch_buf;		/* input buffer */
+	char *yy_buf_pos;		/* current position in input buffer */
+
+	/* Size of input buffer in bytes, not including room for EOB
+	 * characters.
+	 */
+	int yy_buf_size;
+
+	/* Number of characters read into yy_ch_buf, not including EOB
+	 * characters.
+	 */
+	int yy_n_chars;
+
+	/* Whether we "own" the buffer - i.e., we know we created it,
+	 * and can realloc() it to grow it, and should free() it to
+	 * delete it.
+	 */
+	int yy_is_our_buffer;
+
+	/* Whether this is an "interactive" input source; if so, and
+	 * if we're using stdio for input, then we want to use getc()
+	 * instead of fread(), to make sure we stop fetching input after
+	 * each newline.
+	 */
+	int yy_is_interactive;
+
+	/* Whether we're considered to be at the beginning of a line.
+	 * If so, '^' rules will be active on the next match, otherwise
+	 * not.
+	 */
+	int yy_at_bol;
+
+    int yy_bs_lineno; /**< The line count. */
+    int yy_bs_column; /**< The column count. */
+
+	/* Whether to try to fill the input buffer when we reach the
+	 * end of it.
+	 */
+	int yy_fill_buffer;
+
+	int yy_buffer_status;
+
+#define YY_BUFFER_NEW 0
+#define YY_BUFFER_NORMAL 1
+	/* When an EOF's been seen but there's still some text to process
+	 * then we mark the buffer as YY_EOF_PENDING, to indicate that we
+	 * shouldn't try reading from the input source any more.  We might
+	 * still have a bunch of tokens to match, though, because of
+	 * possible backing-up.
+	 *
+	 * When we actually see the EOF, we change the status to "new"
+	 * (via yyrestart()), so that the user can continue scanning by
+	 * just pointing yyin at a new input file.
+	 */
+#define YY_BUFFER_EOF_PENDING 2
+
+	};
+#endif /* !YY_STRUCT_YY_BUFFER_STATE */
+
+/* Stack of input buffers. */
+static size_t yy_buffer_stack_top = 0; /**< index of top of stack. */
+static size_t yy_buffer_stack_max = 0; /**< capacity of stack. */
+static YY_BUFFER_STATE * yy_buffer_stack = NULL; /**< Stack as an array. */
+
+/* We provide macros for accessing buffer states in case in the
+ * future we want to put the buffer states in a more general
+ * "scanner state".
+ *
+ * Returns the top of the stack, or NULL.
+ */
+#define YY_CURRENT_BUFFER ( (yy_buffer_stack) \
+                          ? (yy_buffer_stack)[(yy_buffer_stack_top)] \
+                          : NULL)
+/* Same as previous macro, but useful when we know that the buffer stack is not
+ * NULL or when we need an lvalue. For internal use only.
+ */
+#define YY_CURRENT_BUFFER_LVALUE (yy_buffer_stack)[(yy_buffer_stack_top)]
+
+/* yy_hold_char holds the character lost when yytext is formed. */
+static char yy_hold_char;
+static int yy_n_chars;		/* number of characters read into yy_ch_buf */
+int yyleng;
+
+/* Points to current character in buffer. */
+static char *yy_c_buf_p = NULL;
+static int yy_init = 0;		/* whether we need to initialize */
+static int yy_start = 0;	/* start state number */
+
+/* Flag which is used to allow yywrap()'s to do buffer switches
+ * instead of setting up a fresh yyin.  A bit of a hack ...
+ */
+static int yy_did_buffer_switch_on_eof;
+
+void yyrestart ( FILE *input_file  );
+void yy_switch_to_buffer ( YY_BUFFER_STATE new_buffer  );
+YY_BUFFER_STATE yy_create_buffer ( FILE *file, int size  );
+void yy_delete_buffer ( YY_BUFFER_STATE b  );
+void yy_flush_buffer ( YY_BUFFER_STATE b  );
+void yypush_buffer_state ( YY_BUFFER_STATE new_buffer  );
+void yypop_buffer_state ( void );
+
+static void yyensure_buffer_stack ( void );
+static void yy_load_buffer_state ( void );
+static void yy_init_buffer ( YY_BUFFER_STATE b, FILE *file  );
+#define YY_FLUSH_BUFFER yy_flush_buffer( YY_CURRENT_BUFFER )
+
+YY_BUFFER_STATE yy_scan_buffer ( char *base, yy_size_t size  );
+YY_BUFFER_STATE yy_scan_string ( const char *yy_str  );
+YY_BUFFER_STATE yy_scan_bytes ( const char *bytes, int len  );
+
+void *yyalloc ( yy_size_t  );
+void *yyrealloc ( void *, yy_size_t  );
+void yyfree ( void *  );
+
+#define yy_new_buffer yy_create_buffer
+#define yy_set_interactive(is_interactive) \
+	{ \
+	if ( ! YY_CURRENT_BUFFER ){ \
+        yyensure_buffer_stack (); \
+		YY_CURRENT_BUFFER_LVALUE =    \
+            yy_create_buffer( yyin, YY_BUF_SIZE ); \
+	} \
+	YY_CURRENT_BUFFER_LVALUE->yy_is_interactive = is_interactive; \
+	}
+#define yy_set_bol(at_bol) \
+	{ \
+	if ( ! YY_CURRENT_BUFFER ){\
+        yyensure_buffer_stack (); \
+		YY_CURRENT_BUFFER_LVALUE =    \
+            yy_create_buffer( yyin, YY_BUF_SIZE ); \
+	} \
+	YY_CURRENT_BUFFER_LVALUE->yy_at_bol = at_bol; \
+	}
+#define YY_AT_BOL() (YY_CURRENT_BUFFER_LVALUE->yy_at_bol)
+
+/* Begin user sect3 */
+
+#define GUC_yywrap() (/*CONSTCOND*/1)
+#define YY_SKIP_YYWRAP
+typedef flex_uint8_t YY_CHAR;
+
+FILE *yyin = NULL, *yyout = NULL;
+
+typedef int yy_state_type;
+
+extern int yylineno;
+int yylineno = 1;
+
+extern char *yytext;
+#ifdef yytext_ptr
+#undef yytext_ptr
+#endif
+#define yytext_ptr yytext
+
+static yy_state_type yy_get_previous_state ( void );
+static yy_state_type yy_try_NUL_trans ( yy_state_type current_state  );
+static int yy_get_next_buffer ( void );
+static void yynoreturn yy_fatal_error ( const char* msg  );
+
+/* Done after the current pattern has been matched and before the
+ * corresponding action - sets up yytext.
+ */
+#define YY_DO_BEFORE_ACTION \
+	(yytext_ptr) = yy_bp; \
+	yyleng = (int) (yy_cp - yy_bp); \
+	(yy_hold_char) = *yy_cp; \
+	*yy_cp = '\0'; \
+	(yy_c_buf_p) = yy_cp;
+#define YY_NUM_RULES 12
+#define YY_END_OF_BUFFER 13
+/* This struct is not used in this scanner,
+   but its presence is necessary. */
+struct yy_trans_info
+	{
+	flex_int32_t yy_verify;
+	flex_int32_t yy_nxt;
+	};
+static const flex_int16_t yy_accept[41] =
+    {   0,
+        0,    0,   13,   11,    2,    1,    3,   11,   11,    9,
+        8,    8,   10,    4,    2,    3,    0,    6,    0,    9,
+        8,    8,    9,    0,    8,    8,    7,    7,    4,    4,
+        0,    9,    8,    8,    7,    5,    5,    5,    5,    0
+    } ;
+
+static const YY_CHAR yy_ec[256] =
+    {   0,
+        1,    1,    1,    1,    1,    1,    1,    1,    2,    3,
+        1,    1,    2,    1,    1,    1,    1,    1,    1,    1,
+        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
+        1,    2,    1,    1,    4,    1,    1,    1,    5,    1,
+        1,    1,    6,    1,    7,    8,    9,   10,   11,   11,
+       11,   11,   11,   11,   11,   11,   11,    9,    1,    1,
+       12,    1,    1,    1,   13,   13,   13,   13,   14,   13,
+       15,   15,   15,   15,   15,   15,   15,   15,   15,   15,
+       15,   15,   15,   15,   15,   15,   15,   15,   15,   15,
+        1,   16,    1,    1,   17,    1,   13,   13,   13,   13,
+
+       14,   13,   15,   15,   15,   15,   15,   15,   15,   15,
+       15,   15,   15,   15,   15,   15,   15,   15,   15,   18,
+       15,   15,    1,    1,    1,    1,    1,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19,   19,   19,   19,   19,   19,
+       19,   19,   19,   19,   19
+    } ;
+
+static const YY_CHAR yy_meta[20] =
+    {   0,
+        1,    1,    2,    1,    1,    1,    3,    3,    3,    4,
+        4,    1,    5,    6,    5,    1,    3,    5,    3
+    } ;
+
+static const flex_int16_t yy_base[48] =
+    {   0,
+        0,    0,   50,  148,   43,  148,    0,   15,   24,   30,
+       28,   22,  148,   40,   35,    0,   17,   25,    0,   15,
+        0,   10,    0,   52,    0,   54,   10,   66,   79,    0,
+       13,   15,    0,    0,    4,   90,  101,    0,    0,  148,
+      118,  124,  127,  131,  133,  137,  141
+    } ;
+
+static const flex_int16_t yy_def[48] =
+    {   0,
+       40,    1,   40,   40,   40,   40,   41,   42,   40,   43,
+       40,   11,   40,   44,   40,   41,   42,   40,   42,   43,
+       11,   11,   20,   40,   45,   40,   46,   40,   44,   29,
+       40,   40,   26,   26,   46,   47,   47,   37,   37,    0,
+       40,   40,   40,   40,   40,   40,   40
+    } ;
+
+static const flex_int16_t yy_nxt[168] =
+    {   0,
+        4,    5,    6,    7,    8,    9,    9,   10,    4,   11,
+       12,   13,   14,   14,   14,    4,   14,   14,   14,   18,
+       35,   18,   32,   32,   32,   32,   35,   25,   24,   17,
+       19,   20,   19,   21,   22,   20,   15,   22,   22,   25,
+       25,   25,   25,   24,   15,   26,   27,   28,   27,   40,
+       40,   40,   40,   40,   40,   40,   30,   31,   31,   40,
+       40,   32,   32,   33,   33,   40,   34,   34,   25,   40,
+       40,   25,   27,   27,   27,   27,   27,   40,   36,   36,
+       36,   40,   37,   36,   36,   27,   28,   27,   40,   40,
+       40,   40,   40,   40,   40,   30,   27,   27,   27,   40,
+
+       40,   40,   40,   40,   40,   40,   39,   27,   27,   27,
+       40,   40,   40,   40,   40,   40,   40,   39,   16,   40,
+       16,   16,   16,   16,   17,   40,   17,   17,   17,   17,
+       23,   40,   23,   29,   29,   29,   29,   25,   25,   27,
+       27,   27,   27,   38,   38,   38,   38,    3,   40,   40,
+       40,   40,   40,   40,   40,   40,   40,   40,   40,   40,
+       40,   40,   40,   40,   40,   40,   40
+    } ;
+
+static const flex_int16_t yy_chk[168] =
+    {   0,
+        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
+        1,    1,    1,    1,    1,    1,    1,    1,    1,    8,
+       35,   17,   31,   31,   32,   32,   27,   22,   20,   18,
+        8,    9,   17,    9,    9,   11,   15,   11,   11,   12,
+       11,   11,   11,   10,    5,   11,   14,   14,   14,    3,
+        0,    0,    0,    0,    0,    0,   14,   24,   24,    0,
+        0,   24,   24,   26,   26,    0,   26,   26,   26,    0,
+        0,   26,   28,   28,   28,   28,   28,    0,   28,   28,
+       28,    0,   28,   28,   28,   29,   29,   29,    0,    0,
+        0,    0,    0,    0,    0,   29,   36,   36,   36,    0,
+
+        0,    0,    0,    0,    0,    0,   36,   37,   37,   37,
+        0,    0,    0,    0,    0,    0,    0,   37,   41,    0,
+       41,   41,   41,   41,   42,    0,   42,   42,   42,   42,
+       43,    0,   43,   44,   44,   44,   44,   45,   45,   46,
+       46,   46,   46,   47,   47,   47,   47,   40,   40,   40,
+       40,   40,   40,   40,   40,   40,   40,   40,   40,   40,
+       40,   40,   40,   40,   40,   40,   40
+    } ;
+
+static yy_state_type yy_last_accepting_state;
+static char *yy_last_accepting_cpos;
+
+extern int yy_flex_debug;
+int yy_flex_debug = 0;
+
+/* The intent behind this definition is that it'll catch
+ * any uses of REJECT which flex missed.
+ */
+#define REJECT reject_used_but_not_detected
+#define yymore() yymore_used_but_not_detected
+#define YY_MORE_ADJ 0
+#define YY_RESTORE_YY_MORE_OFFSET
+char *yytext;
+#line 1 "guc-file.l"
+/* -*-pgsql-c-*- */
+/*
+ * Scanner for the configuration file
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ *
+ * src/backend/utils/misc/guc-file.l
+ */
+#line 11 "guc-file.l"
+
+#include "postgres.h"
+
+#include <ctype.h>
+#include <unistd.h>
+
+#include "mb/pg_wchar.h"
+#include "miscadmin.h"
+#include "storage/fd.h"
+#include "utils/guc.h"
+
+
+/*
+ * flex emits a yy_fatal_error() function that it calls in response to
+ * critical errors like malloc failure, file I/O errors, and detection of
+ * internal inconsistency.  That function prints a message and calls exit().
+ * Mutate it to instead call our handler, which jumps out of the parser.
+ */
+#undef fprintf
+#define fprintf(file, fmt, msg) GUC_flex_fatal(msg)
+
+enum
+{
+	GUC_ID = 1,
+	GUC_STRING = 2,
+	GUC_INTEGER = 3,
+	GUC_REAL = 4,
+	GUC_EQUALS = 5,
+	GUC_UNQUOTED_STRING = 6,
+	GUC_QUALIFIED_ID = 7,
+	GUC_EOL = 99,
+	GUC_ERROR = 100
+};
+
+static unsigned int ConfigFileLineno;
+static const char *GUC_flex_fatal_errmsg;
+static sigjmp_buf *GUC_flex_fatal_jmp;
+
+static void FreeConfigVariable(ConfigVariable *item);
+
+static void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+static int	GUC_flex_fatal(const char *msg);
+
+/* LCOV_EXCL_START */
+
+#line 809 "guc-file.c"
+#define YY_NO_INPUT 1
+#line 811 "guc-file.c"
+
+#define INITIAL 0
+
+#ifndef YY_NO_UNISTD_H
+/* Special case for "unistd.h", since it is non-ANSI. We include it way
+ * down here because we want the user's section 1 to have been scanned first.
+ * The user has a chance to override it with an option.
+ */
+#include <unistd.h>
+#endif
+
+#ifndef YY_EXTRA_TYPE
+#define YY_EXTRA_TYPE void *
+#endif
+
+static int yy_init_globals ( void );
+
+/* Accessor methods to globals.
+   These are made visible to non-reentrant scanners for convenience. */
+
+int yylex_destroy ( void );
+
+int yyget_debug ( void );
+
+void yyset_debug ( int debug_flag  );
+
+YY_EXTRA_TYPE yyget_extra ( void );
+
+void yyset_extra ( YY_EXTRA_TYPE user_defined  );
+
+FILE *yyget_in ( void );
+
+void yyset_in  ( FILE * _in_str  );
+
+FILE *yyget_out ( void );
+
+void yyset_out  ( FILE * _out_str  );
+
+			int yyget_leng ( void );
+
+char *yyget_text ( void );
+
+int yyget_lineno ( void );
+
+void yyset_lineno ( int _line_number  );
+
+/* Macros after this point can all be overridden by user definitions in
+ * section 1.
+ */
+
+#ifndef YY_SKIP_YYWRAP
+#ifdef __cplusplus
+extern "C" int yywrap ( void );
+#else
+extern int yywrap ( void );
+#endif
+#endif
+
+#ifndef YY_NO_UNPUT
+    
+#endif
+
+#ifndef yytext_ptr
+static void yy_flex_strncpy ( char *, const char *, int );
+#endif
+
+#ifdef YY_NEED_STRLEN
+static int yy_flex_strlen ( const char * );
+#endif
+
+#ifndef YY_NO_INPUT
+#ifdef __cplusplus
+static int yyinput ( void );
+#else
+static int input ( void );
+#endif
+
+#endif
+
+/* Amount of stuff to slurp up with each read. */
+#ifndef YY_READ_BUF_SIZE
+#ifdef __ia64__
+/* On IA-64, the buffer size is 16k, not 8k */
+#define YY_READ_BUF_SIZE 16384
+#else
+#define YY_READ_BUF_SIZE 8192
+#endif /* __ia64__ */
+#endif
+
+/* Copy whatever the last rule matched to the standard output. */
+#ifndef ECHO
+/* This used to be an fputs(), but since the string might contain NUL's,
+ * we now use fwrite().
+ */
+#define ECHO do { if (fwrite( yytext, (size_t) yyleng, 1, yyout )) {} } while (0)
+#endif
+
+/* Gets input and stuffs it into "buf".  number of characters read, or YY_NULL,
+ * is returned in "result".
+ */
+#ifndef YY_INPUT
+#define YY_INPUT(buf,result,max_size) \
+	if ( YY_CURRENT_BUFFER_LVALUE->yy_is_interactive ) \
+		{ \
+		int c = '*'; \
+		int n; \
+		for ( n = 0; n < max_size && \
+			     (c = getc( yyin )) != EOF && c != '\n'; ++n ) \
+			buf[n] = (char) c; \
+		if ( c == '\n' ) \
+			buf[n++] = (char) c; \
+		if ( c == EOF && ferror( yyin ) ) \
+			YY_FATAL_ERROR( "input in flex scanner failed" ); \
+		result = n; \
+		} \
+	else \
+		{ \
+		errno=0; \
+		while ( (result = (int) fread(buf, 1, (yy_size_t) max_size, yyin)) == 0 && ferror(yyin)) \
+			{ \
+			if( errno != EINTR) \
+				{ \
+				YY_FATAL_ERROR( "input in flex scanner failed" ); \
+				break; \
+				} \
+			errno=0; \
+			clearerr(yyin); \
+			} \
+		}\
+\
+
+#endif
+
+/* No semi-colon after return; correct usage is to write "yyterminate();" -
+ * we don't want an extra ';' after the "return" because that will cause
+ * some compilers to complain about unreachable statements.
+ */
+#ifndef yyterminate
+#define yyterminate() return YY_NULL
+#endif
+
+/* Number of entries by which start-condition stack grows. */
+#ifndef YY_START_STACK_INCR
+#define YY_START_STACK_INCR 25
+#endif
+
+/* Report a fatal error. */
+#ifndef YY_FATAL_ERROR
+#define YY_FATAL_ERROR(msg) yy_fatal_error( msg )
+#endif
+
+/* end tables serialization structures and prototypes */
+
+/* Default declaration of generated scanner - a define so the user can
+ * easily add parameters.
+ */
+#ifndef YY_DECL
+#define YY_DECL_IS_OURS 1
+
+extern int yylex (void);
+
+#define YY_DECL int yylex (void)
+#endif /* !YY_DECL */
+
+/* Code executed at the beginning of each rule, after yytext and yyleng
+ * have been set up.
+ */
+#ifndef YY_USER_ACTION
+#define YY_USER_ACTION
+#endif
+
+/* Code executed at the end of each rule. */
+#ifndef YY_BREAK
+#define YY_BREAK /*LINTED*/break;
+#endif
+
+#define YY_RULE_SETUP \
+	YY_USER_ACTION
+
+/** The main scanner function which does all the work.
+ */
+YY_DECL
+{
+	yy_state_type yy_current_state;
+	char *yy_cp, *yy_bp;
+	int yy_act;
+    
+	if ( !(yy_init) )
+		{
+		(yy_init) = 1;
+
+#ifdef YY_USER_INIT
+		YY_USER_INIT;
+#endif
+
+		if ( ! (yy_start) )
+			(yy_start) = 1;	/* first start state */
+
+		if ( ! yyin )
+			yyin = stdin;
+
+		if ( ! yyout )
+			yyout = stdout;
+
+		if ( ! YY_CURRENT_BUFFER ) {
+			yyensure_buffer_stack ();
+			YY_CURRENT_BUFFER_LVALUE =
+				yy_create_buffer( yyin, YY_BUF_SIZE );
+		}
+
+		yy_load_buffer_state(  );
+		}
+
+	{
+#line 93 "guc-file.l"
+
+
+#line 1029 "guc-file.c"
+
+	while ( /*CONSTCOND*/1 )		/* loops until end-of-file is reached */
+		{
+		yy_cp = (yy_c_buf_p);
+
+		/* Support of yytext. */
+		*yy_cp = (yy_hold_char);
+
+		/* yy_bp points to the position in yy_ch_buf of the start of
+		 * the current run.
+		 */
+		yy_bp = yy_cp;
+
+		yy_current_state = (yy_start);
+yy_match:
+		do
+			{
+			YY_CHAR yy_c = yy_ec[YY_SC_TO_UI(*yy_cp)] ;
+			if ( yy_accept[yy_current_state] )
+				{
+				(yy_last_accepting_state) = yy_current_state;
+				(yy_last_accepting_cpos) = yy_cp;
+				}
+			while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
+				{
+				yy_current_state = (int) yy_def[yy_current_state];
+				if ( yy_current_state >= 41 )
+					yy_c = yy_meta[yy_c];
+				}
+			yy_current_state = yy_nxt[yy_base[yy_current_state] + yy_c];
+			++yy_cp;
+			}
+		while ( yy_current_state != 40 );
+		yy_cp = (yy_last_accepting_cpos);
+		yy_current_state = (yy_last_accepting_state);
+
+yy_find_action:
+		yy_act = yy_accept[yy_current_state];
+
+		YY_DO_BEFORE_ACTION;
+
+do_action:	/* This label is used only to access EOF actions. */
+
+		switch ( yy_act )
+	{ /* beginning of action switch */
+			case 0: /* must back up */
+			/* undo the effects of YY_DO_BEFORE_ACTION */
+			*yy_cp = (yy_hold_char);
+			yy_cp = (yy_last_accepting_cpos);
+			yy_current_state = (yy_last_accepting_state);
+			goto yy_find_action;
+
+case 1:
+/* rule 1 can match eol */
+YY_RULE_SETUP
+#line 95 "guc-file.l"
+ConfigFileLineno++; return GUC_EOL;
+	YY_BREAK
+case 2:
+YY_RULE_SETUP
+#line 96 "guc-file.l"
+/* eat whitespace */
+	YY_BREAK
+case 3:
+YY_RULE_SETUP
+#line 97 "guc-file.l"
+/* eat comment (.* matches anything until newline) */
+	YY_BREAK
+case 4:
+YY_RULE_SETUP
+#line 99 "guc-file.l"
+return GUC_ID;
+	YY_BREAK
+case 5:
+YY_RULE_SETUP
+#line 100 "guc-file.l"
+return GUC_QUALIFIED_ID;
+	YY_BREAK
+case 6:
+YY_RULE_SETUP
+#line 101 "guc-file.l"
+return GUC_STRING;
+	YY_BREAK
+case 7:
+YY_RULE_SETUP
+#line 102 "guc-file.l"
+return GUC_UNQUOTED_STRING;
+	YY_BREAK
+case 8:
+YY_RULE_SETUP
+#line 103 "guc-file.l"
+return GUC_INTEGER;
+	YY_BREAK
+case 9:
+YY_RULE_SETUP
+#line 104 "guc-file.l"
+return GUC_REAL;
+	YY_BREAK
+case 10:
+YY_RULE_SETUP
+#line 105 "guc-file.l"
+return GUC_EQUALS;
+	YY_BREAK
+case 11:
+YY_RULE_SETUP
+#line 107 "guc-file.l"
+return GUC_ERROR;
+	YY_BREAK
+case 12:
+YY_RULE_SETUP
+#line 109 "guc-file.l"
+YY_FATAL_ERROR( "flex scanner jammed" );
+	YY_BREAK
+#line 1143 "guc-file.c"
+case YY_STATE_EOF(INITIAL):
+	yyterminate();
+
+	case YY_END_OF_BUFFER:
+		{
+		/* Amount of text matched not including the EOB char. */
+		int yy_amount_of_matched_text = (int) (yy_cp - (yytext_ptr)) - 1;
+
+		/* Undo the effects of YY_DO_BEFORE_ACTION. */
+		*yy_cp = (yy_hold_char);
+		YY_RESTORE_YY_MORE_OFFSET
+
+		if ( YY_CURRENT_BUFFER_LVALUE->yy_buffer_status == YY_BUFFER_NEW )
+			{
+			/* We're scanning a new file or input source.  It's
+			 * possible that this happened because the user
+			 * just pointed yyin at a new source and called
+			 * yylex().  If so, then we have to assure
+			 * consistency between YY_CURRENT_BUFFER and our
+			 * globals.  Here is the right place to do so, because
+			 * this is the first action (other than possibly a
+			 * back-up) that will match for the new input source.
+			 */
+			(yy_n_chars) = YY_CURRENT_BUFFER_LVALUE->yy_n_chars;
+			YY_CURRENT_BUFFER_LVALUE->yy_input_file = yyin;
+			YY_CURRENT_BUFFER_LVALUE->yy_buffer_status = YY_BUFFER_NORMAL;
+			}
+
+		/* Note that here we test for yy_c_buf_p "<=" to the position
+		 * of the first EOB in the buffer, since yy_c_buf_p will
+		 * already have been incremented past the NUL character
+		 * (since all states make transitions on EOB to the
+		 * end-of-buffer state).  Contrast this with the test
+		 * in input().
+		 */
+		if ( (yy_c_buf_p) <= &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] )
+			{ /* This was really a NUL. */
+			yy_state_type yy_next_state;
+
+			(yy_c_buf_p) = (yytext_ptr) + yy_amount_of_matched_text;
+
+			yy_current_state = yy_get_previous_state(  );
+
+			/* Okay, we're now positioned to make the NUL
+			 * transition.  We couldn't have
+			 * yy_get_previous_state() go ahead and do it
+			 * for us because it doesn't know how to deal
+			 * with the possibility of jamming (and we don't
+			 * want to build jamming into it because then it
+			 * will run more slowly).
+			 */
+
+			yy_next_state = yy_try_NUL_trans( yy_current_state );
+
+			yy_bp = (yytext_ptr) + YY_MORE_ADJ;
+
+			if ( yy_next_state )
+				{
+				/* Consume the NUL. */
+				yy_cp = ++(yy_c_buf_p);
+				yy_current_state = yy_next_state;
+				goto yy_match;
+				}
+
+			else
+				{
+				yy_cp = (yy_last_accepting_cpos);
+				yy_current_state = (yy_last_accepting_state);
+				goto yy_find_action;
+				}
+			}
+
+		else switch ( yy_get_next_buffer(  ) )
+			{
+			case EOB_ACT_END_OF_FILE:
+				{
+				(yy_did_buffer_switch_on_eof) = 0;
+
+				if ( yywrap(  ) )
+					{
+					/* Note: because we've taken care in
+					 * yy_get_next_buffer() to have set up
+					 * yytext, we can now set up
+					 * yy_c_buf_p so that if some total
+					 * hoser (like flex itself) wants to
+					 * call the scanner after we return the
+					 * YY_NULL, it'll still work - another
+					 * YY_NULL will get returned.
+					 */
+					(yy_c_buf_p) = (yytext_ptr) + YY_MORE_ADJ;
+
+					yy_act = YY_STATE_EOF(YY_START);
+					goto do_action;
+					}
+
+				else
+					{
+					if ( ! (yy_did_buffer_switch_on_eof) )
+						YY_NEW_FILE;
+					}
+				break;
+				}
+
+			case EOB_ACT_CONTINUE_SCAN:
+				(yy_c_buf_p) =
+					(yytext_ptr) + yy_amount_of_matched_text;
+
+				yy_current_state = yy_get_previous_state(  );
+
+				yy_cp = (yy_c_buf_p);
+				yy_bp = (yytext_ptr) + YY_MORE_ADJ;
+				goto yy_match;
+
+			case EOB_ACT_LAST_MATCH:
+				(yy_c_buf_p) =
+				&YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)];
+
+				yy_current_state = yy_get_previous_state(  );
+
+				yy_cp = (yy_c_buf_p);
+				yy_bp = (yytext_ptr) + YY_MORE_ADJ;
+				goto yy_find_action;
+			}
+		break;
+		}
+
+	default:
+		YY_FATAL_ERROR(
+			"fatal flex scanner internal error--no action found" );
+	} /* end of action switch */
+		} /* end of scanning one token */
+	} /* end of user's declarations */
+} /* end of yylex */
+
+/* yy_get_next_buffer - try to read in a new buffer
+ *
+ * Returns a code representing an action:
+ *	EOB_ACT_LAST_MATCH -
+ *	EOB_ACT_CONTINUE_SCAN - continue scanning from current position
+ *	EOB_ACT_END_OF_FILE - end of file
+ */
+static int yy_get_next_buffer (void)
+{
+    	char *dest = YY_CURRENT_BUFFER_LVALUE->yy_ch_buf;
+	char *source = (yytext_ptr);
+	int number_to_move, i;
+	int ret_val;
+
+	if ( (yy_c_buf_p) > &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars) + 1] )
+		YY_FATAL_ERROR(
+		"fatal flex scanner internal error--end of buffer missed" );
+
+	if ( YY_CURRENT_BUFFER_LVALUE->yy_fill_buffer == 0 )
+		{ /* Don't try to fill the buffer, so this is an EOF. */
+		if ( (yy_c_buf_p) - (yytext_ptr) - YY_MORE_ADJ == 1 )
+			{
+			/* We matched a single character, the EOB, so
+			 * treat this as a final EOF.
+			 */
+			return EOB_ACT_END_OF_FILE;
+			}
+
+		else
+			{
+			/* We matched some text prior to the EOB, first
+			 * process it.
+			 */
+			return EOB_ACT_LAST_MATCH;
+			}
+		}
+
+	/* Try to read more data. */
+
+	/* First move last chars to start of buffer. */
+	number_to_move = (int) ((yy_c_buf_p) - (yytext_ptr) - 1);
+
+	for ( i = 0; i < number_to_move; ++i )
+		*(dest++) = *(source++);
+
+	if ( YY_CURRENT_BUFFER_LVALUE->yy_buffer_status == YY_BUFFER_EOF_PENDING )
+		/* don't do the read, it's not guaranteed to return an EOF,
+		 * just force an EOF
+		 */
+		YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars) = 0;
+
+	else
+		{
+			int num_to_read =
+			YY_CURRENT_BUFFER_LVALUE->yy_buf_size - number_to_move - 1;
+
+		while ( num_to_read <= 0 )
+			{ /* Not enough room in the buffer - grow it. */
+
+			/* just a shorter name for the current buffer */
+			YY_BUFFER_STATE b = YY_CURRENT_BUFFER_LVALUE;
+
+			int yy_c_buf_p_offset =
+				(int) ((yy_c_buf_p) - b->yy_ch_buf);
+
+			if ( b->yy_is_our_buffer )
+				{
+				int new_size = b->yy_buf_size * 2;
+
+				if ( new_size <= 0 )
+					b->yy_buf_size += b->yy_buf_size / 8;
+				else
+					b->yy_buf_size *= 2;
+
+				b->yy_ch_buf = (char *)
+					/* Include room in for 2 EOB chars. */
+					yyrealloc( (void *) b->yy_ch_buf,
+							 (yy_size_t) (b->yy_buf_size + 2)  );
+				}
+			else
+				/* Can't grow it, we don't own it. */
+				b->yy_ch_buf = NULL;
+
+			if ( ! b->yy_ch_buf )
+				YY_FATAL_ERROR(
+				"fatal error - scanner input buffer overflow" );
+
+			(yy_c_buf_p) = &b->yy_ch_buf[yy_c_buf_p_offset];
+
+			num_to_read = YY_CURRENT_BUFFER_LVALUE->yy_buf_size -
+						number_to_move - 1;
+
+			}
+
+		if ( num_to_read > YY_READ_BUF_SIZE )
+			num_to_read = YY_READ_BUF_SIZE;
+
+		/* Read in more data. */
+		YY_INPUT( (&YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[number_to_move]),
+			(yy_n_chars), num_to_read );
+
+		YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);
+		}
+
+	if ( (yy_n_chars) == 0 )
+		{
+		if ( number_to_move == YY_MORE_ADJ )
+			{
+			ret_val = EOB_ACT_END_OF_FILE;
+			yyrestart( yyin  );
+			}
+
+		else
+			{
+			ret_val = EOB_ACT_LAST_MATCH;
+			YY_CURRENT_BUFFER_LVALUE->yy_buffer_status =
+				YY_BUFFER_EOF_PENDING;
+			}
+		}
+
+	else
+		ret_val = EOB_ACT_CONTINUE_SCAN;
+
+	if (((yy_n_chars) + number_to_move) > YY_CURRENT_BUFFER_LVALUE->yy_buf_size) {
+		/* Extend the array by 50%, plus the number we really need. */
+		int new_size = (yy_n_chars) + number_to_move + ((yy_n_chars) >> 1);
+		YY_CURRENT_BUFFER_LVALUE->yy_ch_buf = (char *) yyrealloc(
+			(void *) YY_CURRENT_BUFFER_LVALUE->yy_ch_buf, (yy_size_t) new_size  );
+		if ( ! YY_CURRENT_BUFFER_LVALUE->yy_ch_buf )
+			YY_FATAL_ERROR( "out of dynamic memory in yy_get_next_buffer()" );
+		/* "- 2" to take care of EOB's */
+		YY_CURRENT_BUFFER_LVALUE->yy_buf_size = (int) (new_size - 2);
+	}
+
+	(yy_n_chars) += number_to_move;
+	YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] = YY_END_OF_BUFFER_CHAR;
+	YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars) + 1] = YY_END_OF_BUFFER_CHAR;
+
+	(yytext_ptr) = &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[0];
+
+	return ret_val;
+}
+
+/* yy_get_previous_state - get the state just before the EOB char was reached */
+
+    static yy_state_type yy_get_previous_state (void)
+{
+	yy_state_type yy_current_state;
+	char *yy_cp;
+    
+	yy_current_state = (yy_start);
+
+	for ( yy_cp = (yytext_ptr) + YY_MORE_ADJ; yy_cp < (yy_c_buf_p); ++yy_cp )
+		{
+		YY_CHAR yy_c = (*yy_cp ? yy_ec[YY_SC_TO_UI(*yy_cp)] : 1);
+		if ( yy_accept[yy_current_state] )
+			{
+			(yy_last_accepting_state) = yy_current_state;
+			(yy_last_accepting_cpos) = yy_cp;
+			}
+		while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
+			{
+			yy_current_state = (int) yy_def[yy_current_state];
+			if ( yy_current_state >= 41 )
+				yy_c = yy_meta[yy_c];
+			}
+		yy_current_state = yy_nxt[yy_base[yy_current_state] + yy_c];
+		}
+
+	return yy_current_state;
+}
+
+/* yy_try_NUL_trans - try to make a transition on the NUL character
+ *
+ * synopsis
+ *	next_state = yy_try_NUL_trans( current_state );
+ */
+    static yy_state_type yy_try_NUL_trans  (yy_state_type yy_current_state )
+{
+	int yy_is_jam;
+    	char *yy_cp = (yy_c_buf_p);
+
+	YY_CHAR yy_c = 1;
+	if ( yy_accept[yy_current_state] )
+		{
+		(yy_last_accepting_state) = yy_current_state;
+		(yy_last_accepting_cpos) = yy_cp;
+		}
+	while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
+		{
+		yy_current_state = (int) yy_def[yy_current_state];
+		if ( yy_current_state >= 41 )
+			yy_c = yy_meta[yy_c];
+		}
+	yy_current_state = yy_nxt[yy_base[yy_current_state] + yy_c];
+	yy_is_jam = (yy_current_state == 40);
+
+		return yy_is_jam ? 0 : yy_current_state;
+}
+
+#ifndef YY_NO_UNPUT
+
+#endif
+
+#ifndef YY_NO_INPUT
+#ifdef __cplusplus
+    static int yyinput (void)
+#else
+    static int input  (void)
+#endif
+
+{
+	int c;
+    
+	*(yy_c_buf_p) = (yy_hold_char);
+
+	if ( *(yy_c_buf_p) == YY_END_OF_BUFFER_CHAR )
+		{
+		/* yy_c_buf_p now points to the character we want to return.
+		 * If this occurs *before* the EOB characters, then it's a
+		 * valid NUL; if not, then we've hit the end of the buffer.
+		 */
+		if ( (yy_c_buf_p) < &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] )
+			/* This was really a NUL. */
+			*(yy_c_buf_p) = '\0';
+
+		else
+			{ /* need more input */
+			int offset = (int) ((yy_c_buf_p) - (yytext_ptr));
+			++(yy_c_buf_p);
+
+			switch ( yy_get_next_buffer(  ) )
+				{
+				case EOB_ACT_LAST_MATCH:
+					/* This happens because yy_g_n_b()
+					 * sees that we've accumulated a
+					 * token and flags that we need to
+					 * try matching the token before
+					 * proceeding.  But for input(),
+					 * there's no matching to consider.
+					 * So convert the EOB_ACT_LAST_MATCH
+					 * to EOB_ACT_END_OF_FILE.
+					 */
+
+					/* Reset buffer status. */
+					yyrestart( yyin );
+
+					/*FALLTHROUGH*/
+
+				case EOB_ACT_END_OF_FILE:
+					{
+					if ( yywrap(  ) )
+						return 0;
+
+					if ( ! (yy_did_buffer_switch_on_eof) )
+						YY_NEW_FILE;
+#ifdef __cplusplus
+					return yyinput();
+#else
+					return input();
+#endif
+					}
+
+				case EOB_ACT_CONTINUE_SCAN:
+					(yy_c_buf_p) = (yytext_ptr) + offset;
+					break;
+				}
+			}
+		}
+
+	c = *(unsigned char *) (yy_c_buf_p);	/* cast for 8-bit char's */
+	*(yy_c_buf_p) = '\0';	/* preserve yytext */
+	(yy_hold_char) = *++(yy_c_buf_p);
+
+	return c;
+}
+#endif	/* ifndef YY_NO_INPUT */
+
+/** Immediately switch to a different input stream.
+ * @param input_file A readable stream.
+ * 
+ * @note This function does not reset the start condition to @c INITIAL .
+ */
+    void yyrestart  (FILE * input_file )
+{
+    
+	if ( ! YY_CURRENT_BUFFER ){
+        yyensure_buffer_stack ();
+		YY_CURRENT_BUFFER_LVALUE =
+            yy_create_buffer( yyin, YY_BUF_SIZE );
+	}
+
+	yy_init_buffer( YY_CURRENT_BUFFER, input_file );
+	yy_load_buffer_state(  );
+}
+
+/** Switch to a different input buffer.
+ * @param new_buffer The new input buffer.
+ * 
+ */
+    void yy_switch_to_buffer  (YY_BUFFER_STATE  new_buffer )
+{
+    
+	/* TODO. We should be able to replace this entire function body
+	 * with
+	 *		yypop_buffer_state();
+	 *		yypush_buffer_state(new_buffer);
+     */
+	yyensure_buffer_stack ();
+	if ( YY_CURRENT_BUFFER == new_buffer )
+		return;
+
+	if ( YY_CURRENT_BUFFER )
+		{
+		/* Flush out information for old buffer. */
+		*(yy_c_buf_p) = (yy_hold_char);
+		YY_CURRENT_BUFFER_LVALUE->yy_buf_pos = (yy_c_buf_p);
+		YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);
+		}
+
+	YY_CURRENT_BUFFER_LVALUE = new_buffer;
+	yy_load_buffer_state(  );
+
+	/* We don't actually know whether we did this switch during
+	 * EOF (yywrap()) processing, but the only time this flag
+	 * is looked at is after yywrap() is called, so it's safe
+	 * to go ahead and always set it.
+	 */
+	(yy_did_buffer_switch_on_eof) = 1;
+}
+
+static void yy_load_buffer_state  (void)
+{
+    	(yy_n_chars) = YY_CURRENT_BUFFER_LVALUE->yy_n_chars;
+	(yytext_ptr) = (yy_c_buf_p) = YY_CURRENT_BUFFER_LVALUE->yy_buf_pos;
+	yyin = YY_CURRENT_BUFFER_LVALUE->yy_input_file;
+	(yy_hold_char) = *(yy_c_buf_p);
+}
+
+/** Allocate and initialize an input buffer state.
+ * @param file A readable stream.
+ * @param size The character buffer size in bytes. When in doubt, use @c YY_BUF_SIZE.
+ * 
+ * @return the allocated buffer state.
+ */
+    YY_BUFFER_STATE yy_create_buffer  (FILE * file, int  size )
+{
+	YY_BUFFER_STATE b;
+    
+	b = (YY_BUFFER_STATE) yyalloc( sizeof( struct yy_buffer_state )  );
+	if ( ! b )
+		YY_FATAL_ERROR( "out of dynamic memory in yy_create_buffer()" );
+
+	b->yy_buf_size = size;
+
+	/* yy_ch_buf has to be 2 characters longer than the size given because
+	 * we need to put in 2 end-of-buffer characters.
+	 */
+	b->yy_ch_buf = (char *) yyalloc( (yy_size_t) (b->yy_buf_size + 2)  );
+	if ( ! b->yy_ch_buf )
+		YY_FATAL_ERROR( "out of dynamic memory in yy_create_buffer()" );
+
+	b->yy_is_our_buffer = 1;
+
+	yy_init_buffer( b, file );
+
+	return b;
+}
+
+/** Destroy the buffer.
+ * @param b a buffer created with yy_create_buffer()
+ * 
+ */
+    void yy_delete_buffer (YY_BUFFER_STATE  b )
+{
+    
+	if ( ! b )
+		return;
+
+	if ( b == YY_CURRENT_BUFFER ) /* Not sure if we should pop here. */
+		YY_CURRENT_BUFFER_LVALUE = (YY_BUFFER_STATE) 0;
+
+	if ( b->yy_is_our_buffer )
+		yyfree( (void *) b->yy_ch_buf  );
+
+	yyfree( (void *) b  );
+}
+
+/* Initializes or reinitializes a buffer.
+ * This function is sometimes called more than once on the same buffer,
+ * such as during a yyrestart() or at EOF.
+ */
+    static void yy_init_buffer  (YY_BUFFER_STATE  b, FILE * file )
+
+{
+	int oerrno = errno;
+    
+	yy_flush_buffer( b );
+
+	b->yy_input_file = file;
+	b->yy_fill_buffer = 1;
+
+    /* If b is the current buffer, then yy_init_buffer was _probably_
+     * called from yyrestart() or through yy_get_next_buffer.
+     * In that case, we don't want to reset the lineno or column.
+     */
+    if (b != YY_CURRENT_BUFFER){
+        b->yy_bs_lineno = 1;
+        b->yy_bs_column = 0;
+    }
+
+        b->yy_is_interactive = 0;
+    
+	errno = oerrno;
+}
+
+/** Discard all buffered characters. On the next scan, YY_INPUT will be called.
+ * @param b the buffer state to be flushed, usually @c YY_CURRENT_BUFFER.
+ * 
+ */
+    void yy_flush_buffer (YY_BUFFER_STATE  b )
+{
+    	if ( ! b )
+		return;
+
+	b->yy_n_chars = 0;
+
+	/* We always need two end-of-buffer characters.  The first causes
+	 * a transition to the end-of-buffer state.  The second causes
+	 * a jam in that state.
+	 */
+	b->yy_ch_buf[0] = YY_END_OF_BUFFER_CHAR;
+	b->yy_ch_buf[1] = YY_END_OF_BUFFER_CHAR;
+
+	b->yy_buf_pos = &b->yy_ch_buf[0];
+
+	b->yy_at_bol = 1;
+	b->yy_buffer_status = YY_BUFFER_NEW;
+
+	if ( b == YY_CURRENT_BUFFER )
+		yy_load_buffer_state(  );
+}
+
+/** Pushes the new state onto the stack. The new state becomes
+ *  the current state. This function will allocate the stack
+ *  if necessary.
+ *  @param new_buffer The new state.
+ *  
+ */
+void yypush_buffer_state (YY_BUFFER_STATE new_buffer )
+{
+    	if (new_buffer == NULL)
+		return;
+
+	yyensure_buffer_stack();
+
+	/* This block is copied from yy_switch_to_buffer. */
+	if ( YY_CURRENT_BUFFER )
+		{
+		/* Flush out information for old buffer. */
+		*(yy_c_buf_p) = (yy_hold_char);
+		YY_CURRENT_BUFFER_LVALUE->yy_buf_pos = (yy_c_buf_p);
+		YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);
+		}
+
+	/* Only push if top exists. Otherwise, replace top. */
+	if (YY_CURRENT_BUFFER)
+		(yy_buffer_stack_top)++;
+	YY_CURRENT_BUFFER_LVALUE = new_buffer;
+
+	/* copied from yy_switch_to_buffer. */
+	yy_load_buffer_state(  );
+	(yy_did_buffer_switch_on_eof) = 1;
+}
+
+/** Removes and deletes the top of the stack, if present.
+ *  The next element becomes the new top.
+ *  
+ */
+void yypop_buffer_state (void)
+{
+    	if (!YY_CURRENT_BUFFER)
+		return;
+
+	yy_delete_buffer(YY_CURRENT_BUFFER );
+	YY_CURRENT_BUFFER_LVALUE = NULL;
+	if ((yy_buffer_stack_top) > 0)
+		--(yy_buffer_stack_top);
+
+	if (YY_CURRENT_BUFFER) {
+		yy_load_buffer_state(  );
+		(yy_did_buffer_switch_on_eof) = 1;
+	}
+}
+
+/* Allocates the stack if it does not exist.
+ *  Guarantees space for at least one push.
+ */
+static void yyensure_buffer_stack (void)
+{
+	yy_size_t num_to_alloc;
+    
+	if (!(yy_buffer_stack)) {
+
+		/* First allocation is just for 2 elements, since we don't know if this
+		 * scanner will even need a stack. We use 2 instead of 1 to avoid an
+		 * immediate realloc on the next call.
+         */
+      num_to_alloc = 1; /* After all that talk, this was set to 1 anyways... */
+		(yy_buffer_stack) = (struct yy_buffer_state**)yyalloc
+								(num_to_alloc * sizeof(struct yy_buffer_state*)
+								);
+		if ( ! (yy_buffer_stack) )
+			YY_FATAL_ERROR( "out of dynamic memory in yyensure_buffer_stack()" );
+
+		memset((yy_buffer_stack), 0, num_to_alloc * sizeof(struct yy_buffer_state*));
+
+		(yy_buffer_stack_max) = num_to_alloc;
+		(yy_buffer_stack_top) = 0;
+		return;
+	}
+
+	if ((yy_buffer_stack_top) >= ((yy_buffer_stack_max)) - 1){
+
+		/* Increase the buffer to prepare for a possible push. */
+		yy_size_t grow_size = 8 /* arbitrary grow size */;
+
+		num_to_alloc = (yy_buffer_stack_max) + grow_size;
+		(yy_buffer_stack) = (struct yy_buffer_state**)yyrealloc
+								((yy_buffer_stack),
+								num_to_alloc * sizeof(struct yy_buffer_state*)
+								);
+		if ( ! (yy_buffer_stack) )
+			YY_FATAL_ERROR( "out of dynamic memory in yyensure_buffer_stack()" );
+
+		/* zero only the new slots.*/
+		memset((yy_buffer_stack) + (yy_buffer_stack_max), 0, grow_size * sizeof(struct yy_buffer_state*));
+		(yy_buffer_stack_max) = num_to_alloc;
+	}
+}
+
+/** Setup the input buffer state to scan directly from a user-specified character buffer.
+ * @param base the character buffer
+ * @param size the size in bytes of the character buffer
+ * 
+ * @return the newly allocated buffer state object.
+ */
+YY_BUFFER_STATE yy_scan_buffer  (char * base, yy_size_t  size )
+{
+	YY_BUFFER_STATE b;
+    
+	if ( size < 2 ||
+	     base[size-2] != YY_END_OF_BUFFER_CHAR ||
+	     base[size-1] != YY_END_OF_BUFFER_CHAR )
+		/* They forgot to leave room for the EOB's. */
+		return NULL;
+
+	b = (YY_BUFFER_STATE) yyalloc( sizeof( struct yy_buffer_state )  );
+	if ( ! b )
+		YY_FATAL_ERROR( "out of dynamic memory in yy_scan_buffer()" );
+
+	b->yy_buf_size = (int) (size - 2);	/* "- 2" to take care of EOB's */
+	b->yy_buf_pos = b->yy_ch_buf = base;
+	b->yy_is_our_buffer = 0;
+	b->yy_input_file = NULL;
+	b->yy_n_chars = b->yy_buf_size;
+	b->yy_is_interactive = 0;
+	b->yy_at_bol = 1;
+	b->yy_fill_buffer = 0;
+	b->yy_buffer_status = YY_BUFFER_NEW;
+
+	yy_switch_to_buffer( b  );
+
+	return b;
+}
+
+/** Setup the input buffer state to scan a string. The next call to yylex() will
+ * scan from a @e copy of @a str.
+ * @param yystr a NUL-terminated string to scan
+ * 
+ * @return the newly allocated buffer state object.
+ * @note If you want to scan bytes that may contain NUL values, then use
+ *       yy_scan_bytes() instead.
+ */
+YY_BUFFER_STATE yy_scan_string (const char * yystr )
+{
+    
+	return yy_scan_bytes( yystr, (int) strlen(yystr) );
+}
+
+/** Setup the input buffer state to scan the given bytes. The next call to yylex() will
+ * scan from a @e copy of @a bytes.
+ * @param yybytes the byte buffer to scan
+ * @param _yybytes_len the number of bytes in the buffer pointed to by @a bytes.
+ * 
+ * @return the newly allocated buffer state object.
+ */
+YY_BUFFER_STATE yy_scan_bytes  (const char * yybytes, int  _yybytes_len )
+{
+	YY_BUFFER_STATE b;
+	char *buf;
+	yy_size_t n;
+	int i;
+    
+	/* Get memory for full buffer, including space for trailing EOB's. */
+	n = (yy_size_t) (_yybytes_len + 2);
+	buf = (char *) yyalloc( n  );
+	if ( ! buf )
+		YY_FATAL_ERROR( "out of dynamic memory in yy_scan_bytes()" );
+
+	for ( i = 0; i < _yybytes_len; ++i )
+		buf[i] = yybytes[i];
+
+	buf[_yybytes_len] = buf[_yybytes_len+1] = YY_END_OF_BUFFER_CHAR;
+
+	b = yy_scan_buffer( buf, n );
+	if ( ! b )
+		YY_FATAL_ERROR( "bad buffer in yy_scan_bytes()" );
+
+	/* It's okay to grow etc. this buffer, and we should throw it
+	 * away when we're done.
+	 */
+	b->yy_is_our_buffer = 1;
+
+	return b;
+}
+
+#ifndef YY_EXIT_FAILURE
+#define YY_EXIT_FAILURE 2
+#endif
+
+static void yynoreturn yy_fatal_error (const char* msg )
+{
+			fprintf( stderr, "%s\n", msg );
+	exit( YY_EXIT_FAILURE );
+}
+
+/* Redefine yyless() so it works in section 3 code. */
+
+#undef yyless
+#define yyless(n) \
+	do \
+		{ \
+		/* Undo effects of setting up yytext. */ \
+        int yyless_macro_arg = (n); \
+        YY_LESS_LINENO(yyless_macro_arg);\
+		yytext[yyleng] = (yy_hold_char); \
+		(yy_c_buf_p) = yytext + yyless_macro_arg; \
+		(yy_hold_char) = *(yy_c_buf_p); \
+		*(yy_c_buf_p) = '\0'; \
+		yyleng = yyless_macro_arg; \
+		} \
+	while ( 0 )
+
+/* Accessor  methods (get/set functions) to struct members. */
+
+/** Get the current line number.
+ * 
+ */
+int yyget_lineno  (void)
+{
+    
+    return yylineno;
+}
+
+/** Get the input stream.
+ * 
+ */
+FILE *yyget_in  (void)
+{
+        return yyin;
+}
+
+/** Get the output stream.
+ * 
+ */
+FILE *yyget_out  (void)
+{
+        return yyout;
+}
+
+/** Get the length of the current token.
+ * 
+ */
+int yyget_leng  (void)
+{
+        return yyleng;
+}
+
+/** Get the current token.
+ * 
+ */
+
+char *yyget_text  (void)
+{
+        return yytext;
+}
+
+/** Set the current line number.
+ * @param _line_number line number
+ * 
+ */
+void yyset_lineno (int  _line_number )
+{
+    
+    yylineno = _line_number;
+}
+
+/** Set the input stream. This does not discard the current
+ * input buffer.
+ * @param _in_str A readable stream.
+ * 
+ * @see yy_switch_to_buffer
+ */
+void yyset_in (FILE *  _in_str )
+{
+        yyin = _in_str ;
+}
+
+void yyset_out (FILE *  _out_str )
+{
+        yyout = _out_str ;
+}
+
+int yyget_debug  (void)
+{
+        return yy_flex_debug;
+}
+
+void yyset_debug (int  _bdebug )
+{
+        yy_flex_debug = _bdebug ;
+}
+
+static int yy_init_globals (void)
+{
+        /* Initialization is the same as for the non-reentrant scanner.
+     * This function is called from yylex_destroy(), so don't allocate here.
+     */
+
+    (yy_buffer_stack) = NULL;
+    (yy_buffer_stack_top) = 0;
+    (yy_buffer_stack_max) = 0;
+    (yy_c_buf_p) = NULL;
+    (yy_init) = 0;
+    (yy_start) = 0;
+
+/* Defined in main.c */
+#ifdef YY_STDINIT
+    yyin = stdin;
+    yyout = stdout;
+#else
+    yyin = NULL;
+    yyout = NULL;
+#endif
+
+    /* For future reference: Set errno on error, since we are called by
+     * yylex_init()
+     */
+    return 0;
+}
+
+/* yylex_destroy is for both reentrant and non-reentrant scanners. */
+int yylex_destroy  (void)
+{
+    
+    /* Pop the buffer stack, destroying each element. */
+	while(YY_CURRENT_BUFFER){
+		yy_delete_buffer( YY_CURRENT_BUFFER  );
+		YY_CURRENT_BUFFER_LVALUE = NULL;
+		yypop_buffer_state();
+	}
+
+	/* Destroy the stack itself. */
+	yyfree((yy_buffer_stack) );
+	(yy_buffer_stack) = NULL;
+
+    /* Reset the globals. This is important in a non-reentrant scanner so the next time
+     * yylex() is called, initialization will occur. */
+    yy_init_globals( );
+
+    return 0;
+}
+
+/*
+ * Internal utility routines.
+ */
+
+#ifndef yytext_ptr
+static void yy_flex_strncpy (char* s1, const char * s2, int n )
+{
+		
+	int i;
+	for ( i = 0; i < n; ++i )
+		s1[i] = s2[i];
+}
+#endif
+
+#ifdef YY_NEED_STRLEN
+static int yy_flex_strlen (const char * s )
+{
+	int n;
+	for ( n = 0; s[n]; ++n )
+		;
+
+	return n;
+}
+#endif
+
+void *yyalloc (yy_size_t  size )
+{
+			return malloc(size);
+}
+
+void *yyrealloc  (void * ptr, yy_size_t  size )
+{
+		
+	/* The cast to (char *) in the following accommodates both
+	 * implementations that use char* generic pointers, and those
+	 * that use void* generic pointers.  It works with the latter
+	 * because both ANSI C and C++ allow castless assignment from
+	 * any pointer type to void*, and deal with argument conversions
+	 * as though doing an assignment.
+	 */
+	return realloc(ptr, size);
+}
+
+void yyfree (void * ptr )
+{
+			free( (char *) ptr );	/* see yyrealloc() for (char *) cast */
+}
+
+#define YYTABLES_NAME "yytables"
+
+#line 109 "guc-file.l"
+
+
+/* LCOV_EXCL_STOP */
+
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, true, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (!valid_custom_variable_name(item->name))
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %d",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			/* The removal can't be effective without a restart */
+			gconf->status |= GUC_PENDING_RESTART;
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
+
+/*
+ * Given a configuration file or directory location that may be a relative
+ * path, return an absolute one.  We consider the location to be relative to
+ * the directory holding the calling file, or to DataDir if no calling file.
+ */
+static char *
+AbsoluteConfigLocation(const char *location, const char *calling_file)
+{
+	char		abs_path[MAXPGPATH];
+
+	if (is_absolute_path(location))
+		return pstrdup(location);
+	else
+	{
+		if (calling_file != NULL)
+		{
+			strlcpy(abs_path, calling_file, sizeof(abs_path));
+			get_parent_directory(abs_path);
+			join_path_components(abs_path, abs_path, location);
+			canonicalize_path(abs_path);
+		}
+		else
+		{
+			AssertState(DataDir);
+			join_path_components(abs_path, DataDir, location);
+			canonicalize_path(abs_path);
+		}
+		return pstrdup(abs_path);
+	}
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * If "strict" is true, treat failure to open the config file as an error,
+ * otherwise just skip the file.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.  This one merely adds opening the
+ * config file rather than working from a caller-supplied file descriptor,
+ * and absolute-ifying the path name if necessary.
+ */
+bool
+ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p,
+				ConfigVariable **tail_p)
+{
+	char	   *abs_path;
+	bool		OK = true;
+	FILE	   *fp;
+
+	/*
+	 * Reject file name that is all-blank (including empty), as that leads to
+	 * confusion --- we'd try to read the containing directory as a file.
+	 */
+	if (strspn(config_file, " \t\r\n") == strlen(config_file))
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("empty configuration file name: \"%s\"",
+						config_file)));
+		record_config_file_error("empty configuration file name",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	/*
+	 * Reject too-deep include nesting depth.  This is just a safety check to
+	 * avoid dumping core due to stack overflow if an include file loops back
+	 * to itself.  The maximum nesting depth is pretty arbitrary.
+	 */
+	if (depth > 10)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
+						config_file)));
+		record_config_file_error("nesting depth exceeded",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+
+	/*
+	 * Reject direct recursion.  Indirect recursion is also possible, but it's
+	 * harder to detect and so doesn't seem worth the trouble.  (We test at
+	 * this step because the canonicalization done by AbsoluteConfigLocation
+	 * makes it more likely that a simple strcmp comparison will match.)
+	 */
+	if (calling_file && strcmp(abs_path, calling_file) == 0)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("configuration file recursion in \"%s\"",
+						calling_file)));
+		record_config_file_error("configuration file recursion",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		pfree(abs_path);
+		return false;
+	}
+
+	fp = AllocateFile(abs_path, "r");
+	if (!fp)
+	{
+		if (strict)
+		{
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not open configuration file \"%s\": %m",
+							abs_path)));
+			record_config_file_error(psprintf("could not open file \"%s\"",
+											  abs_path),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			OK = false;
+		}
+		else
+		{
+			ereport(LOG,
+					(errmsg("skipping missing configuration file \"%s\"",
+							abs_path)));
+		}
+		goto cleanup;
+	}
+
+	OK = ParseConfigFp(fp, abs_path, depth, elevel, head_p, tail_p);
+
+cleanup:
+	if (fp)
+		FreeFile(fp);
+	pfree(abs_path);
+
+	return OK;
+}
+
+/*
+ * Capture an error message in the ConfigVariable list returned by
+ * config file parsing.
+ */
+static void
+record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p)
+{
+	ConfigVariable *item;
+
+	item = palloc(sizeof *item);
+	item->name = NULL;
+	item->value = NULL;
+	item->errmsg = pstrdup(errmsg);
+	item->filename = config_file ? pstrdup(config_file) : NULL;
+	item->sourceline = lineno;
+	item->ignore = true;
+	item->applied = false;
+	item->next = NULL;
+	if (*head_p == NULL)
+		*head_p = item;
+	else
+		(*tail_p)->next = item;
+	*tail_p = item;
+}
+
+/*
+ * Flex fatal errors bring us here.  Stash the error message and jump back to
+ * ParseConfigFp().  Assume all msg arguments point to string constants; this
+ * holds for flex 2.5.31 (earliest we support) and flex 2.5.35 (latest as of
+ * this writing).  Otherwise, we would need to copy the message.
+ *
+ * We return "int" since this takes the place of calls to fprintf().
+*/
+static int
+GUC_flex_fatal(const char *msg)
+{
+	GUC_flex_fatal_errmsg = msg;
+	siglongjmp(*GUC_flex_fatal_jmp, 1);
+	return 0;					/* keep compiler quiet */
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * Input parameters:
+ *	fp: file pointer from AllocateFile for the configuration file to parse
+ *	config_file: absolute or relative path name of the configuration file
+ *	depth: recursion depth (should be 0 in the outermost call)
+ *	elevel: error logging level to use
+ * Input/Output parameters:
+ *	head_p, tail_p: head and tail of linked list of name/value pairs
+ *
+ * *head_p and *tail_p must be initialized, either to NULL or valid pointers
+ * to a ConfigVariable list, before calling the outer recursion level.  Any
+ * name-value pairs read from the input file(s) will be appended to the list.
+ * Error reports will also be appended to the list, if elevel < ERROR.
+ *
+ * Returns TRUE if successful, FALSE if an error occurred.  The error has
+ * already been ereport'd, it is only necessary for the caller to clean up
+ * its own state and release the ConfigVariable list.
+ *
+ * Note: if elevel >= ERROR then an error will not return control to the
+ * caller, so there is no need to check the return value in that case.
+ *
+ * Note: this function is used to parse not only postgresql.conf, but
+ * various other configuration files that use the same "name = value"
+ * syntax.  Hence, do not do anything here or in the subsidiary routines
+ * ParseConfigFile/ParseConfigDirectory that assumes we are processing
+ * GUCs specifically.
+ */
+bool
+ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p)
+{
+	volatile bool OK = true;
+	unsigned int save_ConfigFileLineno = ConfigFileLineno;
+	sigjmp_buf *save_GUC_flex_fatal_jmp = GUC_flex_fatal_jmp;
+	sigjmp_buf	flex_fatal_jmp;
+	volatile YY_BUFFER_STATE lex_buffer = NULL;
+	int			errorcount;
+	int			token;
+
+	if (sigsetjmp(flex_fatal_jmp, 1) == 0)
+		GUC_flex_fatal_jmp = &flex_fatal_jmp;
+	else
+	{
+		/*
+		 * Regain control after a fatal, internal flex error.  It may have
+		 * corrupted parser state.  Consequently, abandon the file, but trust
+		 * that the state remains sane enough for yy_delete_buffer().
+		 */
+		elog(elevel, "%s at file \"%s\" line %u",
+			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		record_config_file_error(GUC_flex_fatal_errmsg,
+								 config_file, ConfigFileLineno,
+								 head_p, tail_p);
+		OK = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Parse
+	 */
+	ConfigFileLineno = 1;
+	errorcount = 0;
+
+	lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
+	yy_switch_to_buffer(lex_buffer);
+
+	/* This loop iterates once per logical line */
+	while ((token = yylex()))
+	{
+		char	   *opt_name = NULL;
+		char	   *opt_value = NULL;
+		ConfigVariable *item;
+
+		if (token == GUC_EOL)	/* empty or comment line */
+			continue;
+
+		/* first token on line is option name */
+		if (token != GUC_ID && token != GUC_QUALIFIED_ID)
+			goto parse_error;
+		opt_name = pstrdup(yytext);
+
+		/* next we have an optional equal sign; discard if present */
+		token = yylex();
+		if (token == GUC_EQUALS)
+			token = yylex();
+
+		/* now we must have the option value */
+		if (token != GUC_ID &&
+			token != GUC_STRING &&
+			token != GUC_INTEGER &&
+			token != GUC_REAL &&
+			token != GUC_UNQUOTED_STRING)
+			goto parse_error;
+		if (token == GUC_STRING)	/* strip quotes and escapes */
+			opt_value = DeescapeQuotedString(yytext);
+		else
+			opt_value = pstrdup(yytext);
+
+		/* now we'd like an end of line, or possibly EOF */
+		token = yylex();
+		if (token != GUC_EOL)
+		{
+			if (token != 0)
+				goto parse_error;
+			/* treat EOF like \n for line numbering purposes, cf bug 4752 */
+			ConfigFileLineno++;
+		}
+
+		/* OK, process the option name and value */
+		if (guc_name_compare(opt_name, "include_dir") == 0)
+		{
+			/*
+			 * An include_dir directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigDirectory(opt_value,
+									  config_file, ConfigFileLineno - 1,
+									  depth + 1, elevel,
+									  head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include_if_exists") == 0)
+		{
+			/*
+			 * An include_if_exists directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigFile(opt_value, false,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include") == 0)
+		{
+			/*
+			 * An include directive isn't a variable and should be processed
+			 * immediately.
+			 */
+			if (!ParseConfigFile(opt_value, true,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else
+		{
+			/* ordinary variable, append to list */
+			item = palloc(sizeof *item);
+			item->name = opt_name;
+			item->value = opt_value;
+			item->errmsg = NULL;
+			item->filename = pstrdup(config_file);
+			item->sourceline = ConfigFileLineno - 1;
+			item->ignore = false;
+			item->applied = false;
+			item->next = NULL;
+			if (*head_p == NULL)
+				*head_p = item;
+			else
+				(*tail_p)->next = item;
+			*tail_p = item;
+		}
+
+		/* break out of loop if read EOF, else loop for next line */
+		if (token == 0)
+			break;
+		continue;
+
+parse_error:
+		/* release storage if we allocated any on this line */
+		if (opt_name)
+			pfree(opt_name);
+		if (opt_value)
+			pfree(opt_value);
+
+		/* report the error */
+		if (token == GUC_EOL || token == 0)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			  errmsg("syntax error in file \"%s\" line %u, near end of line",
+					 config_file, ConfigFileLineno - 1)));
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno - 1,
+									 head_p, tail_p);
+		}
+		else
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
+					config_file, ConfigFileLineno, yytext)));
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno,
+									 head_p, tail_p);
+		}
+		OK = false;
+		errorcount++;
+
+		/*
+		 * To avoid producing too much noise when fed a totally bogus file,
+		 * give up after 100 syntax errors per file (an arbitrary number).
+		 * Also, if we're only logging the errors at DEBUG level anyway, might
+		 * as well give up immediately.  (This prevents postmaster children
+		 * from bloating the logs with duplicate complaints.)
+		 */
+		if (errorcount >= 100 || elevel <= DEBUG1)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+			   errmsg("too many syntax errors found, abandoning file \"%s\"",
+					  config_file)));
+			break;
+		}
+
+		/* resync to next end-of-line or EOF */
+		while (token != GUC_EOL && token != 0)
+			token = yylex();
+		/* break out of loop on EOF */
+		if (token == 0)
+			break;
+	}
+
+cleanup:
+	yy_delete_buffer(lex_buffer);
+	/* Each recursion level must save and restore these static variables. */
+	ConfigFileLineno = save_ConfigFileLineno;
+	GUC_flex_fatal_jmp = save_GUC_flex_fatal_jmp;
+	return OK;
+}
+
+/*
+ * Read and parse all config files in a subdirectory in alphabetical order
+ *
+ * includedir is the absolute or relative path to the subdirectory to scan.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.
+ */
+bool
+ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p)
+{
+	char	   *directory;
+	DIR		   *d;
+	struct dirent *de;
+	char	  **filenames;
+	int			num_filenames;
+	int			size_filenames;
+	bool		status;
+
+	/*
+	 * Reject directory name that is all-blank (including empty), as that
+	 * leads to confusion --- we'd read the containing directory, typically
+	 * resulting in recursive inclusion of the same file(s).
+	 */
+	if (strspn(includedir, " \t\r\n") == strlen(includedir))
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("empty configuration directory name: \"%s\"",
+						includedir)));
+		record_config_file_error("empty configuration directory name",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	/*
+	 * We don't check for recursion or too-deep nesting depth here; the
+	 * subsequent calls to ParseConfigFile will take care of that.
+	 */
+
+	directory = AbsoluteConfigLocation(includedir, calling_file);
+	d = AllocateDir(directory);
+	if (d == NULL)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not open configuration directory \"%s\": %m",
+						directory)));
+		record_config_file_error(psprintf("could not open directory \"%s\"",
+										  directory),
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		status = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Read the directory and put the filenames in an array, so we can sort
+	 * them prior to processing the contents.
+	 */
+	size_filenames = 32;
+	filenames = (char **) palloc(size_filenames * sizeof(char *));
+	num_filenames = 0;
+
+	while ((de = ReadDir(d, directory)) != NULL)
+	{
+		struct stat st;
+		char		filename[MAXPGPATH];
+
+		/*
+		 * Only parse files with names ending in ".conf".  Explicitly reject
+		 * files starting with ".".  This excludes things like "." and "..",
+		 * as well as typical hidden files, backup files, and editor debris.
+		 */
+		if (strlen(de->d_name) < 6)
+			continue;
+		if (de->d_name[0] == '.')
+			continue;
+		if (strcmp(de->d_name + strlen(de->d_name) - 5, ".conf") != 0)
+			continue;
+
+		join_path_components(filename, directory, de->d_name);
+		canonicalize_path(filename);
+		if (stat(filename, &st) == 0)
+		{
+			if (!S_ISDIR(st.st_mode))
+			{
+				/* Add file to array, increasing its size in blocks of 32 */
+				if (num_filenames >= size_filenames)
+				{
+					size_filenames += 32;
+					filenames = (char **) repalloc(filenames,
+											size_filenames * sizeof(char *));
+				}
+				filenames[num_filenames] = pstrdup(filename);
+				num_filenames++;
+			}
+		}
+		else
+		{
+			/*
+			 * stat does not care about permissions, so the most likely reason
+			 * a file can't be accessed now is if it was removed between the
+			 * directory listing and now.
+			 */
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not stat file \"%s\": %m",
+							filename)));
+			record_config_file_error(psprintf("could not stat file \"%s\"",
+											  filename),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			status = false;
+			goto cleanup;
+		}
+	}
+
+	if (num_filenames > 0)
+	{
+		int			i;
+
+		qsort(filenames, num_filenames, sizeof(char *), pg_qsort_strcmp);
+		for (i = 0; i < num_filenames; i++)
+		{
+			if (!ParseConfigFile(filenames[i], true,
+								 calling_file, calling_lineno,
+								 depth, elevel,
+								 head_p, tail_p))
+			{
+				status = false;
+				goto cleanup;
+			}
+		}
+	}
+	status = true;
+
+cleanup:
+	if (d)
+		FreeDir(d);
+	pfree(directory);
+	return status;
+}
+
+/*
+ * Free a list of ConfigVariables, including the names and the values
+ */
+void
+FreeConfigVariables(ConfigVariable *list)
+{
+	ConfigVariable *item;
+
+	item = list;
+	while (item)
+	{
+		ConfigVariable *next = item->next;
+
+		FreeConfigVariable(item);
+		item = next;
+	}
+}
+
+/*
+ * Free a single ConfigVariable
+ */
+static void
+FreeConfigVariable(ConfigVariable *item)
+{
+	if (item->name)
+		pfree(item->name);
+	if (item->value)
+		pfree(item->value);
+	if (item->errmsg)
+		pfree(item->errmsg);
+	if (item->filename)
+		pfree(item->filename);
+	pfree(item);
+}
+
+
+/*
+ *		DeescapeQuotedString
+ *
+ * Strip the quotes surrounding the given string, and collapse any embedded
+ * '' sequences and backslash escapes.
+ *
+ * The string returned is palloc'd and should eventually be pfree'd by the
+ * caller.
+ *
+ * This is exported because it is also used by the bootstrap scanner.
+ */
+char *
+DeescapeQuotedString(const char *s)
+{
+	char	   *newStr;
+	int			len,
+				i,
+				j;
+
+	/* We just Assert that there are leading and trailing quotes */
+	Assert(s != NULL && s[0] == '\'');
+	len = strlen(s);
+	Assert(len >= 2);
+	Assert(s[len - 1] == '\'');
+
+	/* Skip the leading quote; we'll handle the trailing quote below */
+	s++, len--;
+
+	/* Since len still includes trailing quote, this is enough space */
+	newStr = palloc(len);
+
+	for (i = 0, j = 0; i < len; i++)
+	{
+		if (s[i] == '\\')
+		{
+			i++;
+			switch (s[i])
+			{
+				case 'b':
+					newStr[j] = '\b';
+					break;
+				case 'f':
+					newStr[j] = '\f';
+					break;
+				case 'n':
+					newStr[j] = '\n';
+					break;
+				case 'r':
+					newStr[j] = '\r';
+					break;
+				case 't':
+					newStr[j] = '\t';
+					break;
+				case '0':
+				case '1':
+				case '2':
+				case '3':
+				case '4':
+				case '5':
+				case '6':
+				case '7':
+					{
+						int			k;
+						long		octVal = 0;
+
+						for (k = 0;
+							 s[i + k] >= '0' && s[i + k] <= '7' && k < 3;
+							 k++)
+							octVal = (octVal << 3) + (s[i + k] - '0');
+						i += k - 1;
+						newStr[j] = ((char) octVal);
+					}
+					break;
+				default:
+					newStr[j] = s[i];
+					break;
+			}					/* switch */
+		}
+		else if (s[i] == '\'' && s[i + 1] == '\'')
+		{
+			/* doubled quote becomes just one quote */
+			newStr[j] = s[++i];
+		}
+		else
+			newStr[j] = s[i];
+		j++;
+	}
+
+	/* We copied the ending quote to newStr, so replace with \0 */
+	Assert(j > 0 && j <= len);
+	newStr[--j] = '\0';
+
+	return newStr;
+}
+
diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
new file mode 100644
index 0000000..8ca74c8
--- /dev/null
+++ b/src/backend/utils/misc/guc-file.l
@@ -0,0 +1,1228 @@
+/* -*-pgsql-c-*- */
+/*
+ * Scanner for the configuration file
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ *
+ * src/backend/utils/misc/guc-file.l
+ */
+
+%{
+
+#include "postgres.h"
+
+#include <ctype.h>
+#include <unistd.h>
+
+#include "mb/pg_wchar.h"
+#include "miscadmin.h"
+#include "storage/fd.h"
+#include "utils/guc.h"
+
+
+/*
+ * flex emits a yy_fatal_error() function that it calls in response to
+ * critical errors like malloc failure, file I/O errors, and detection of
+ * internal inconsistency.  That function prints a message and calls exit().
+ * Mutate it to instead call our handler, which jumps out of the parser.
+ */
+#undef fprintf
+#define fprintf(file, fmt, msg) GUC_flex_fatal(msg)
+
+enum
+{
+	GUC_ID = 1,
+	GUC_STRING = 2,
+	GUC_INTEGER = 3,
+	GUC_REAL = 4,
+	GUC_EQUALS = 5,
+	GUC_UNQUOTED_STRING = 6,
+	GUC_QUALIFIED_ID = 7,
+	GUC_EOL = 99,
+	GUC_ERROR = 100
+};
+
+static unsigned int ConfigFileLineno;
+static const char *GUC_flex_fatal_errmsg;
+static sigjmp_buf *GUC_flex_fatal_jmp;
+
+static void FreeConfigVariable(ConfigVariable *item);
+
+static void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+static int	GUC_flex_fatal(const char *msg);
+
+/* LCOV_EXCL_START */
+
+%}
+
+%option 8bit
+%option never-interactive
+%option nodefault
+%option noinput
+%option nounput
+%option noyywrap
+%option warn
+%option prefix="GUC_yy"
+
+
+SIGN			("-"|"+")
+DIGIT			[0-9]
+HEXDIGIT		[0-9a-fA-F]
+
+UNIT_LETTER		[a-zA-Z]
+
+INTEGER			{SIGN}?({DIGIT}+|0x{HEXDIGIT}+){UNIT_LETTER}*
+
+EXPONENT		[Ee]{SIGN}?{DIGIT}+
+REAL			{SIGN}?{DIGIT}*"."{DIGIT}*{EXPONENT}?
+
+LETTER			[A-Za-z_\200-\377]
+LETTER_OR_DIGIT [A-Za-z_0-9\200-\377]
+
+ID				{LETTER}{LETTER_OR_DIGIT}*
+QUALIFIED_ID	{ID}"."{ID}
+
+UNQUOTED_STRING {LETTER}({LETTER_OR_DIGIT}|[-._:/])*
+STRING			\'([^'\\\n]|\\.|\'\')*\'
+
+%%
+
+\n				ConfigFileLineno++; return GUC_EOL;
+[ \t\r]+		/* eat whitespace */
+#.*				/* eat comment (.* matches anything until newline) */
+
+{ID}			return GUC_ID;
+{QUALIFIED_ID}	return GUC_QUALIFIED_ID;
+{STRING}		return GUC_STRING;
+{UNQUOTED_STRING} return GUC_UNQUOTED_STRING;
+{INTEGER}		return GUC_INTEGER;
+{REAL}			return GUC_REAL;
+=				return GUC_EQUALS;
+
+.				return GUC_ERROR;
+
+%%
+
+/* LCOV_EXCL_STOP */
+
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, true, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (!valid_custom_variable_name(item->name))
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %d",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			/* The removal can't be effective without a restart */
+			gconf->status |= GUC_PENDING_RESTART;
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
+
+/*
+ * Given a configuration file or directory location that may be a relative
+ * path, return an absolute one.  We consider the location to be relative to
+ * the directory holding the calling file, or to DataDir if no calling file.
+ */
+static char *
+AbsoluteConfigLocation(const char *location, const char *calling_file)
+{
+	char		abs_path[MAXPGPATH];
+
+	if (is_absolute_path(location))
+		return pstrdup(location);
+	else
+	{
+		if (calling_file != NULL)
+		{
+			strlcpy(abs_path, calling_file, sizeof(abs_path));
+			get_parent_directory(abs_path);
+			join_path_components(abs_path, abs_path, location);
+			canonicalize_path(abs_path);
+		}
+		else
+		{
+			AssertState(DataDir);
+			join_path_components(abs_path, DataDir, location);
+			canonicalize_path(abs_path);
+		}
+		return pstrdup(abs_path);
+	}
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * If "strict" is true, treat failure to open the config file as an error,
+ * otherwise just skip the file.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.  This one merely adds opening the
+ * config file rather than working from a caller-supplied file descriptor,
+ * and absolute-ifying the path name if necessary.
+ */
+bool
+ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p,
+				ConfigVariable **tail_p)
+{
+	char	   *abs_path;
+	bool		OK = true;
+	FILE	   *fp;
+
+	/*
+	 * Reject file name that is all-blank (including empty), as that leads to
+	 * confusion --- we'd try to read the containing directory as a file.
+	 */
+	if (strspn(config_file, " \t\r\n") == strlen(config_file))
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("empty configuration file name: \"%s\"",
+						config_file)));
+		record_config_file_error("empty configuration file name",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	/*
+	 * Reject too-deep include nesting depth.  This is just a safety check to
+	 * avoid dumping core due to stack overflow if an include file loops back
+	 * to itself.  The maximum nesting depth is pretty arbitrary.
+	 */
+	if (depth > 10)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
+						config_file)));
+		record_config_file_error("nesting depth exceeded",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+
+	/*
+	 * Reject direct recursion.  Indirect recursion is also possible, but it's
+	 * harder to detect and so doesn't seem worth the trouble.  (We test at
+	 * this step because the canonicalization done by AbsoluteConfigLocation
+	 * makes it more likely that a simple strcmp comparison will match.)
+	 */
+	if (calling_file && strcmp(abs_path, calling_file) == 0)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("configuration file recursion in \"%s\"",
+						calling_file)));
+		record_config_file_error("configuration file recursion",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		pfree(abs_path);
+		return false;
+	}
+
+	fp = AllocateFile(abs_path, "r");
+	if (!fp)
+	{
+		if (strict)
+		{
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not open configuration file \"%s\": %m",
+							abs_path)));
+			record_config_file_error(psprintf("could not open file \"%s\"",
+											  abs_path),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			OK = false;
+		}
+		else
+		{
+			ereport(LOG,
+					(errmsg("skipping missing configuration file \"%s\"",
+							abs_path)));
+		}
+		goto cleanup;
+	}
+
+	OK = ParseConfigFp(fp, abs_path, depth, elevel, head_p, tail_p);
+
+cleanup:
+	if (fp)
+		FreeFile(fp);
+	pfree(abs_path);
+
+	return OK;
+}
+
+/*
+ * Capture an error message in the ConfigVariable list returned by
+ * config file parsing.
+ */
+static void
+record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p)
+{
+	ConfigVariable *item;
+
+	item = palloc(sizeof *item);
+	item->name = NULL;
+	item->value = NULL;
+	item->errmsg = pstrdup(errmsg);
+	item->filename = config_file ? pstrdup(config_file) : NULL;
+	item->sourceline = lineno;
+	item->ignore = true;
+	item->applied = false;
+	item->next = NULL;
+	if (*head_p == NULL)
+		*head_p = item;
+	else
+		(*tail_p)->next = item;
+	*tail_p = item;
+}
+
+/*
+ * Flex fatal errors bring us here.  Stash the error message and jump back to
+ * ParseConfigFp().  Assume all msg arguments point to string constants; this
+ * holds for flex 2.5.31 (earliest we support) and flex 2.5.35 (latest as of
+ * this writing).  Otherwise, we would need to copy the message.
+ *
+ * We return "int" since this takes the place of calls to fprintf().
+*/
+static int
+GUC_flex_fatal(const char *msg)
+{
+	GUC_flex_fatal_errmsg = msg;
+	siglongjmp(*GUC_flex_fatal_jmp, 1);
+	return 0;					/* keep compiler quiet */
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * Input parameters:
+ *	fp: file pointer from AllocateFile for the configuration file to parse
+ *	config_file: absolute or relative path name of the configuration file
+ *	depth: recursion depth (should be 0 in the outermost call)
+ *	elevel: error logging level to use
+ * Input/Output parameters:
+ *	head_p, tail_p: head and tail of linked list of name/value pairs
+ *
+ * *head_p and *tail_p must be initialized, either to NULL or valid pointers
+ * to a ConfigVariable list, before calling the outer recursion level.  Any
+ * name-value pairs read from the input file(s) will be appended to the list.
+ * Error reports will also be appended to the list, if elevel < ERROR.
+ *
+ * Returns TRUE if successful, FALSE if an error occurred.  The error has
+ * already been ereport'd, it is only necessary for the caller to clean up
+ * its own state and release the ConfigVariable list.
+ *
+ * Note: if elevel >= ERROR then an error will not return control to the
+ * caller, so there is no need to check the return value in that case.
+ *
+ * Note: this function is used to parse not only postgresql.conf, but
+ * various other configuration files that use the same "name = value"
+ * syntax.  Hence, do not do anything here or in the subsidiary routines
+ * ParseConfigFile/ParseConfigDirectory that assumes we are processing
+ * GUCs specifically.
+ */
+bool
+ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p)
+{
+	volatile bool OK = true;
+	unsigned int save_ConfigFileLineno = ConfigFileLineno;
+	sigjmp_buf *save_GUC_flex_fatal_jmp = GUC_flex_fatal_jmp;
+	sigjmp_buf	flex_fatal_jmp;
+	volatile YY_BUFFER_STATE lex_buffer = NULL;
+	int			errorcount;
+	int			token;
+
+	if (sigsetjmp(flex_fatal_jmp, 1) == 0)
+		GUC_flex_fatal_jmp = &flex_fatal_jmp;
+	else
+	{
+		/*
+		 * Regain control after a fatal, internal flex error.  It may have
+		 * corrupted parser state.  Consequently, abandon the file, but trust
+		 * that the state remains sane enough for yy_delete_buffer().
+		 */
+		elog(elevel, "%s at file \"%s\" line %u",
+			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		record_config_file_error(GUC_flex_fatal_errmsg,
+								 config_file, ConfigFileLineno,
+								 head_p, tail_p);
+		OK = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Parse
+	 */
+	ConfigFileLineno = 1;
+	errorcount = 0;
+
+	lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
+	yy_switch_to_buffer(lex_buffer);
+
+	/* This loop iterates once per logical line */
+	while ((token = yylex()))
+	{
+		char	   *opt_name = NULL;
+		char	   *opt_value = NULL;
+		ConfigVariable *item;
+
+		if (token == GUC_EOL)	/* empty or comment line */
+			continue;
+
+		/* first token on line is option name */
+		if (token != GUC_ID && token != GUC_QUALIFIED_ID)
+			goto parse_error;
+		opt_name = pstrdup(yytext);
+
+		/* next we have an optional equal sign; discard if present */
+		token = yylex();
+		if (token == GUC_EQUALS)
+			token = yylex();
+
+		/* now we must have the option value */
+		if (token != GUC_ID &&
+			token != GUC_STRING &&
+			token != GUC_INTEGER &&
+			token != GUC_REAL &&
+			token != GUC_UNQUOTED_STRING)
+			goto parse_error;
+		if (token == GUC_STRING)	/* strip quotes and escapes */
+			opt_value = DeescapeQuotedString(yytext);
+		else
+			opt_value = pstrdup(yytext);
+
+		/* now we'd like an end of line, or possibly EOF */
+		token = yylex();
+		if (token != GUC_EOL)
+		{
+			if (token != 0)
+				goto parse_error;
+			/* treat EOF like \n for line numbering purposes, cf bug 4752 */
+			ConfigFileLineno++;
+		}
+
+		/* OK, process the option name and value */
+		if (guc_name_compare(opt_name, "include_dir") == 0)
+		{
+			/*
+			 * An include_dir directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigDirectory(opt_value,
+									  config_file, ConfigFileLineno - 1,
+									  depth + 1, elevel,
+									  head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include_if_exists") == 0)
+		{
+			/*
+			 * An include_if_exists directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigFile(opt_value, false,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include") == 0)
+		{
+			/*
+			 * An include directive isn't a variable and should be processed
+			 * immediately.
+			 */
+			if (!ParseConfigFile(opt_value, true,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else
+		{
+			/* ordinary variable, append to list */
+			item = palloc(sizeof *item);
+			item->name = opt_name;
+			item->value = opt_value;
+			item->errmsg = NULL;
+			item->filename = pstrdup(config_file);
+			item->sourceline = ConfigFileLineno - 1;
+			item->ignore = false;
+			item->applied = false;
+			item->next = NULL;
+			if (*head_p == NULL)
+				*head_p = item;
+			else
+				(*tail_p)->next = item;
+			*tail_p = item;
+		}
+
+		/* break out of loop if read EOF, else loop for next line */
+		if (token == 0)
+			break;
+		continue;
+
+parse_error:
+		/* release storage if we allocated any on this line */
+		if (opt_name)
+			pfree(opt_name);
+		if (opt_value)
+			pfree(opt_value);
+
+		/* report the error */
+		if (token == GUC_EOL || token == 0)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			  errmsg("syntax error in file \"%s\" line %u, near end of line",
+					 config_file, ConfigFileLineno - 1)));
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno - 1,
+									 head_p, tail_p);
+		}
+		else
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
+					config_file, ConfigFileLineno, yytext)));
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno,
+									 head_p, tail_p);
+		}
+		OK = false;
+		errorcount++;
+
+		/*
+		 * To avoid producing too much noise when fed a totally bogus file,
+		 * give up after 100 syntax errors per file (an arbitrary number).
+		 * Also, if we're only logging the errors at DEBUG level anyway, might
+		 * as well give up immediately.  (This prevents postmaster children
+		 * from bloating the logs with duplicate complaints.)
+		 */
+		if (errorcount >= 100 || elevel <= DEBUG1)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+			   errmsg("too many syntax errors found, abandoning file \"%s\"",
+					  config_file)));
+			break;
+		}
+
+		/* resync to next end-of-line or EOF */
+		while (token != GUC_EOL && token != 0)
+			token = yylex();
+		/* break out of loop on EOF */
+		if (token == 0)
+			break;
+	}
+
+cleanup:
+	yy_delete_buffer(lex_buffer);
+	/* Each recursion level must save and restore these static variables. */
+	ConfigFileLineno = save_ConfigFileLineno;
+	GUC_flex_fatal_jmp = save_GUC_flex_fatal_jmp;
+	return OK;
+}
+
+/*
+ * Read and parse all config files in a subdirectory in alphabetical order
+ *
+ * includedir is the absolute or relative path to the subdirectory to scan.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.
+ */
+bool
+ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p)
+{
+	char	   *directory;
+	DIR		   *d;
+	struct dirent *de;
+	char	  **filenames;
+	int			num_filenames;
+	int			size_filenames;
+	bool		status;
+
+	/*
+	 * Reject directory name that is all-blank (including empty), as that
+	 * leads to confusion --- we'd read the containing directory, typically
+	 * resulting in recursive inclusion of the same file(s).
+	 */
+	if (strspn(includedir, " \t\r\n") == strlen(includedir))
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("empty configuration directory name: \"%s\"",
+						includedir)));
+		record_config_file_error("empty configuration directory name",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	/*
+	 * We don't check for recursion or too-deep nesting depth here; the
+	 * subsequent calls to ParseConfigFile will take care of that.
+	 */
+
+	directory = AbsoluteConfigLocation(includedir, calling_file);
+	d = AllocateDir(directory);
+	if (d == NULL)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not open configuration directory \"%s\": %m",
+						directory)));
+		record_config_file_error(psprintf("could not open directory \"%s\"",
+										  directory),
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		status = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Read the directory and put the filenames in an array, so we can sort
+	 * them prior to processing the contents.
+	 */
+	size_filenames = 32;
+	filenames = (char **) palloc(size_filenames * sizeof(char *));
+	num_filenames = 0;
+
+	while ((de = ReadDir(d, directory)) != NULL)
+	{
+		struct stat st;
+		char		filename[MAXPGPATH];
+
+		/*
+		 * Only parse files with names ending in ".conf".  Explicitly reject
+		 * files starting with ".".  This excludes things like "." and "..",
+		 * as well as typical hidden files, backup files, and editor debris.
+		 */
+		if (strlen(de->d_name) < 6)
+			continue;
+		if (de->d_name[0] == '.')
+			continue;
+		if (strcmp(de->d_name + strlen(de->d_name) - 5, ".conf") != 0)
+			continue;
+
+		join_path_components(filename, directory, de->d_name);
+		canonicalize_path(filename);
+		if (stat(filename, &st) == 0)
+		{
+			if (!S_ISDIR(st.st_mode))
+			{
+				/* Add file to array, increasing its size in blocks of 32 */
+				if (num_filenames >= size_filenames)
+				{
+					size_filenames += 32;
+					filenames = (char **) repalloc(filenames,
+											size_filenames * sizeof(char *));
+				}
+				filenames[num_filenames] = pstrdup(filename);
+				num_filenames++;
+			}
+		}
+		else
+		{
+			/*
+			 * stat does not care about permissions, so the most likely reason
+			 * a file can't be accessed now is if it was removed between the
+			 * directory listing and now.
+			 */
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not stat file \"%s\": %m",
+							filename)));
+			record_config_file_error(psprintf("could not stat file \"%s\"",
+											  filename),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			status = false;
+			goto cleanup;
+		}
+	}
+
+	if (num_filenames > 0)
+	{
+		int			i;
+
+		qsort(filenames, num_filenames, sizeof(char *), pg_qsort_strcmp);
+		for (i = 0; i < num_filenames; i++)
+		{
+			if (!ParseConfigFile(filenames[i], true,
+								 calling_file, calling_lineno,
+								 depth, elevel,
+								 head_p, tail_p))
+			{
+				status = false;
+				goto cleanup;
+			}
+		}
+	}
+	status = true;
+
+cleanup:
+	if (d)
+		FreeDir(d);
+	pfree(directory);
+	return status;
+}
+
+/*
+ * Free a list of ConfigVariables, including the names and the values
+ */
+void
+FreeConfigVariables(ConfigVariable *list)
+{
+	ConfigVariable *item;
+
+	item = list;
+	while (item)
+	{
+		ConfigVariable *next = item->next;
+
+		FreeConfigVariable(item);
+		item = next;
+	}
+}
+
+/*
+ * Free a single ConfigVariable
+ */
+static void
+FreeConfigVariable(ConfigVariable *item)
+{
+	if (item->name)
+		pfree(item->name);
+	if (item->value)
+		pfree(item->value);
+	if (item->errmsg)
+		pfree(item->errmsg);
+	if (item->filename)
+		pfree(item->filename);
+	pfree(item);
+}
+
+
+/*
+ *		DeescapeQuotedString
+ *
+ * Strip the quotes surrounding the given string, and collapse any embedded
+ * '' sequences and backslash escapes.
+ *
+ * The string returned is palloc'd and should eventually be pfree'd by the
+ * caller.
+ *
+ * This is exported because it is also used by the bootstrap scanner.
+ */
+char *
+DeescapeQuotedString(const char *s)
+{
+	char	   *newStr;
+	int			len,
+				i,
+				j;
+
+	/* We just Assert that there are leading and trailing quotes */
+	Assert(s != NULL && s[0] == '\'');
+	len = strlen(s);
+	Assert(len >= 2);
+	Assert(s[len - 1] == '\'');
+
+	/* Skip the leading quote; we'll handle the trailing quote below */
+	s++, len--;
+
+	/* Since len still includes trailing quote, this is enough space */
+	newStr = palloc(len);
+
+	for (i = 0, j = 0; i < len; i++)
+	{
+		if (s[i] == '\\')
+		{
+			i++;
+			switch (s[i])
+			{
+				case 'b':
+					newStr[j] = '\b';
+					break;
+				case 'f':
+					newStr[j] = '\f';
+					break;
+				case 'n':
+					newStr[j] = '\n';
+					break;
+				case 'r':
+					newStr[j] = '\r';
+					break;
+				case 't':
+					newStr[j] = '\t';
+					break;
+				case '0':
+				case '1':
+				case '2':
+				case '3':
+				case '4':
+				case '5':
+				case '6':
+				case '7':
+					{
+						int			k;
+						long		octVal = 0;
+
+						for (k = 0;
+							 s[i + k] >= '0' && s[i + k] <= '7' && k < 3;
+							 k++)
+							octVal = (octVal << 3) + (s[i + k] - '0');
+						i += k - 1;
+						newStr[j] = ((char) octVal);
+					}
+					break;
+				default:
+					newStr[j] = s[i];
+					break;
+			}					/* switch */
+		}
+		else if (s[i] == '\'' && s[i + 1] == '\'')
+		{
+			/* doubled quote becomes just one quote */
+			newStr[j] = s[++i];
+		}
+		else
+			newStr[j] = s[i];
+		j++;
+	}
+
+	/* We copied the ending quote to newStr, so replace with \0 */
+	Assert(j > 0 && j <= len);
+	newStr[--j] = '\0';
+
+	return newStr;
+}
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
new file mode 100644
index 0000000..ef62bb8
--- /dev/null
+++ b/src/backend/utils/misc/guc.c
@@ -0,0 +1,12546 @@
+/*--------------------------------------------------------------------
+ * guc.c
+ *
+ * Support for grand unified configuration scheme, including SET
+ * command, configuration file, and command line options.
+ * See src/backend/utils/misc/README for more information.
+ *
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ * Written by Peter Eisentraut <peter_e@gmx.net>.
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/guc.c
+ *
+ *--------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <ctype.h>
+#include <float.h>
+#include <math.h>
+#include <limits.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
+#ifndef WIN32
+#include <sys/mman.h>
+#endif
+#include <sys/stat.h>
+#ifdef HAVE_SYSLOG
+#include <syslog.h>
+#endif
+#include <unistd.h>
+
+#include "access/commit_ts.h"
+#include "access/gin.h"
+#include "access/rmgr.h"
+#include "access/tableam.h"
+#include "access/toast_compression.h"
+#include "access/transam.h"
+#include "access/twophase.h"
+#include "access/xact.h"
+#include "access/xlog_internal.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_authid.h"
+#include "catalog/storage.h"
+#include "commands/async.h"
+#include "commands/prepare.h"
+#include "commands/tablespace.h"
+#include "commands/trigger.h"
+#include "commands/user.h"
+#include "commands/vacuum.h"
+#include "commands/variable.h"
+#include "common/string.h"
+#include "funcapi.h"
+#include "jit/jit.h"
+#include "libpq/auth.h"
+#include "libpq/libpq.h"
+#include "libpq/pqformat.h"
+#include "miscadmin.h"
+#include "optimizer/cost.h"
+#include "optimizer/geqo.h"
+#include "optimizer/optimizer.h"
+#include "optimizer/paths.h"
+#include "optimizer/planmain.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_type.h"
+#include "parser/parser.h"
+#include "parser/scansup.h"
+#include "pgstat.h"
+#include "postmaster/autovacuum.h"
+#include "postmaster/bgworker_internals.h"
+#include "postmaster/bgwriter.h"
+#include "postmaster/postmaster.h"
+#include "postmaster/syslogger.h"
+#include "postmaster/walwriter.h"
+#include "replication/logicallauncher.h"
+#include "replication/reorderbuffer.h"
+#include "replication/slot.h"
+#include "replication/syncrep.h"
+#include "replication/walreceiver.h"
+#include "replication/walsender.h"
+#include "storage/bufmgr.h"
+#include "storage/dsm_impl.h"
+#include "storage/fd.h"
+#include "storage/large_object.h"
+#include "storage/pg_shmem.h"
+#include "storage/predicate.h"
+#include "storage/proc.h"
+#include "storage/standby.h"
+#include "tcop/tcopprot.h"
+#include "tsearch/ts_cache.h"
+#include "utils/acl.h"
+#include "utils/backend_status.h"
+#include "utils/builtins.h"
+#include "utils/bytea.h"
+#include "utils/float.h"
+#include "utils/guc_tables.h"
+#include "utils/memutils.h"
+#include "utils/pg_locale.h"
+#include "utils/pg_lsn.h"
+#include "utils/plancache.h"
+#include "utils/portal.h"
+#include "utils/ps_status.h"
+#include "utils/queryjumble.h"
+#include "utils/rls.h"
+#include "utils/snapmgr.h"
+#include "utils/tzparser.h"
+#include "utils/inval.h"
+#include "utils/varlena.h"
+#include "utils/xml.h"
+
+#ifndef PG_KRB_SRVTAB
+#define PG_KRB_SRVTAB ""
+#endif
+
+#define CONFIG_FILENAME "postgresql.conf"
+#define HBA_FILENAME	"pg_hba.conf"
+#define IDENT_FILENAME	"pg_ident.conf"
+
+#ifdef EXEC_BACKEND
+#define CONFIG_EXEC_PARAMS "global/config_exec_params"
+#define CONFIG_EXEC_PARAMS_NEW "global/config_exec_params.new"
+#endif
+
+/*
+ * Precision with which REAL type guc values are to be printed for GUC
+ * serialization.
+ */
+#define REALTYPE_PRECISION 17
+
+/* XXX these should appear in other modules' header files */
+extern bool Log_disconnections;
+extern int	CommitDelay;
+extern int	CommitSiblings;
+extern char *default_tablespace;
+extern char *temp_tablespaces;
+extern bool ignore_checksum_failure;
+extern bool ignore_invalid_pages;
+extern bool synchronize_seqscans;
+
+#ifdef TRACE_SYNCSCAN
+extern bool trace_syncscan;
+#endif
+#ifdef DEBUG_BOUNDED_SORT
+extern bool optimize_bounded_sort;
+#endif
+
+static int	GUC_check_errcode_value;
+
+/* global variables for check hook support */
+char	   *GUC_check_errmsg_string;
+char	   *GUC_check_errdetail_string;
+char	   *GUC_check_errhint_string;
+
+static void do_serialize(char **destptr, Size *maxbytes, const char *fmt,...) pg_attribute_printf(3, 4);
+
+static void set_config_sourcefile(const char *name, char *sourcefile,
+								  int sourceline);
+static bool call_bool_check_hook(struct config_bool *conf, bool *newval,
+								 void **extra, GucSource source, int elevel);
+static bool call_int_check_hook(struct config_int *conf, int *newval,
+								void **extra, GucSource source, int elevel);
+static bool call_real_check_hook(struct config_real *conf, double *newval,
+								 void **extra, GucSource source, int elevel);
+static bool call_string_check_hook(struct config_string *conf, char **newval,
+								   void **extra, GucSource source, int elevel);
+static bool call_enum_check_hook(struct config_enum *conf, int *newval,
+								 void **extra, GucSource source, int elevel);
+
+static bool check_log_destination(char **newval, void **extra, GucSource source);
+static void assign_log_destination(const char *newval, void *extra);
+
+static bool check_wal_consistency_checking(char **newval, void **extra,
+										   GucSource source);
+static void assign_wal_consistency_checking(const char *newval, void *extra);
+
+#ifdef HAVE_SYSLOG
+static int	syslog_facility = LOG_LOCAL0;
+#else
+static int	syslog_facility = 0;
+#endif
+
+static void assign_syslog_facility(int newval, void *extra);
+static void assign_syslog_ident(const char *newval, void *extra);
+static void assign_session_replication_role(int newval, void *extra);
+static bool check_temp_buffers(int *newval, void **extra, GucSource source);
+static bool check_bonjour(bool *newval, void **extra, GucSource source);
+static bool check_ssl(bool *newval, void **extra, GucSource source);
+static bool check_stage_log_stats(bool *newval, void **extra, GucSource source);
+static bool check_log_stats(bool *newval, void **extra, GucSource source);
+static bool check_canonical_path(char **newval, void **extra, GucSource source);
+static bool check_timezone_abbreviations(char **newval, void **extra, GucSource source);
+static void assign_timezone_abbreviations(const char *newval, void *extra);
+static void pg_timezone_abbrev_initialize(void);
+static const char *show_archive_command(void);
+static void assign_tcp_keepalives_idle(int newval, void *extra);
+static void assign_tcp_keepalives_interval(int newval, void *extra);
+static void assign_tcp_keepalives_count(int newval, void *extra);
+static void assign_tcp_user_timeout(int newval, void *extra);
+static const char *show_tcp_keepalives_idle(void);
+static const char *show_tcp_keepalives_interval(void);
+static const char *show_tcp_keepalives_count(void);
+static const char *show_tcp_user_timeout(void);
+static bool check_maxconnections(int *newval, void **extra, GucSource source);
+static bool check_max_worker_processes(int *newval, void **extra, GucSource source);
+static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource source);
+static bool check_max_wal_senders(int *newval, void **extra, GucSource source);
+static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source);
+static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
+static bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
+static bool check_huge_page_size(int *newval, void **extra, GucSource source);
+static bool check_client_connection_check_interval(int *newval, void **extra, GucSource source);
+static void assign_pgstat_temp_directory(const char *newval, void *extra);
+static bool check_application_name(char **newval, void **extra, GucSource source);
+static void assign_application_name(const char *newval, void *extra);
+static bool check_cluster_name(char **newval, void **extra, GucSource source);
+static const char *show_unix_socket_permissions(void);
+static const char *show_log_file_mode(void);
+static const char *show_data_directory_mode(void);
+static const char *show_in_hot_standby(void);
+static bool check_backtrace_functions(char **newval, void **extra, GucSource source);
+static void assign_backtrace_functions(const char *newval, void *extra);
+static bool check_recovery_target_timeline(char **newval, void **extra, GucSource source);
+static void assign_recovery_target_timeline(const char *newval, void *extra);
+static bool check_recovery_target(char **newval, void **extra, GucSource source);
+static void assign_recovery_target(const char *newval, void *extra);
+static bool check_recovery_target_xid(char **newval, void **extra, GucSource source);
+static void assign_recovery_target_xid(const char *newval, void *extra);
+static bool check_recovery_target_time(char **newval, void **extra, GucSource source);
+static void assign_recovery_target_time(const char *newval, void *extra);
+static bool check_recovery_target_name(char **newval, void **extra, GucSource source);
+static void assign_recovery_target_name(const char *newval, void *extra);
+static bool check_recovery_target_lsn(char **newval, void **extra, GucSource source);
+static void assign_recovery_target_lsn(const char *newval, void *extra);
+static bool check_primary_slot_name(char **newval, void **extra, GucSource source);
+static bool check_default_with_oids(bool *newval, void **extra, GucSource source);
+
+/* Private functions in guc-file.l that need to be called from guc.c */
+static ConfigVariable *ProcessConfigFileInternal(GucContext context,
+												 bool applySettings, int elevel);
+
+
+/*
+ * Options for enum values defined in this module.
+ *
+ * NOTE! Option values may not contain double quotes!
+ */
+
+static const struct config_enum_entry bytea_output_options[] = {
+	{"escape", BYTEA_OUTPUT_ESCAPE, false},
+	{"hex", BYTEA_OUTPUT_HEX, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(bytea_output_options) == (BYTEA_OUTPUT_HEX + 2),
+				 "array length mismatch");
+
+/*
+ * We have different sets for client and server message level options because
+ * they sort slightly different (see "log" level), and because "fatal"/"panic"
+ * aren't sensible for client_min_messages.
+ */
+static const struct config_enum_entry client_message_level_options[] = {
+	{"debug5", DEBUG5, false},
+	{"debug4", DEBUG4, false},
+	{"debug3", DEBUG3, false},
+	{"debug2", DEBUG2, false},
+	{"debug1", DEBUG1, false},
+	{"debug", DEBUG2, true},
+	{"log", LOG, false},
+	{"info", INFO, true},
+	{"notice", NOTICE, false},
+	{"warning", WARNING, false},
+	{"error", ERROR, false},
+	{NULL, 0, false}
+};
+
+static const struct config_enum_entry server_message_level_options[] = {
+	{"debug5", DEBUG5, false},
+	{"debug4", DEBUG4, false},
+	{"debug3", DEBUG3, false},
+	{"debug2", DEBUG2, false},
+	{"debug1", DEBUG1, false},
+	{"debug", DEBUG2, true},
+	{"info", INFO, false},
+	{"notice", NOTICE, false},
+	{"warning", WARNING, false},
+	{"error", ERROR, false},
+	{"log", LOG, false},
+	{"fatal", FATAL, false},
+	{"panic", PANIC, false},
+	{NULL, 0, false}
+};
+
+static const struct config_enum_entry intervalstyle_options[] = {
+	{"postgres", INTSTYLE_POSTGRES, false},
+	{"postgres_verbose", INTSTYLE_POSTGRES_VERBOSE, false},
+	{"sql_standard", INTSTYLE_SQL_STANDARD, false},
+	{"iso_8601", INTSTYLE_ISO_8601, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(intervalstyle_options) == (INTSTYLE_ISO_8601 + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry log_error_verbosity_options[] = {
+	{"terse", PGERROR_TERSE, false},
+	{"default", PGERROR_DEFAULT, false},
+	{"verbose", PGERROR_VERBOSE, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(log_error_verbosity_options) == (PGERROR_VERBOSE + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry log_statement_options[] = {
+	{"none", LOGSTMT_NONE, false},
+	{"ddl", LOGSTMT_DDL, false},
+	{"mod", LOGSTMT_MOD, false},
+	{"all", LOGSTMT_ALL, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(log_statement_options) == (LOGSTMT_ALL + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry isolation_level_options[] = {
+	{"serializable", XACT_SERIALIZABLE, false},
+	{"repeatable read", XACT_REPEATABLE_READ, false},
+	{"read committed", XACT_READ_COMMITTED, false},
+	{"read uncommitted", XACT_READ_UNCOMMITTED, false},
+	{NULL, 0}
+};
+
+static const struct config_enum_entry session_replication_role_options[] = {
+	{"origin", SESSION_REPLICATION_ROLE_ORIGIN, false},
+	{"replica", SESSION_REPLICATION_ROLE_REPLICA, false},
+	{"local", SESSION_REPLICATION_ROLE_LOCAL, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(session_replication_role_options) == (SESSION_REPLICATION_ROLE_LOCAL + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry syslog_facility_options[] = {
+#ifdef HAVE_SYSLOG
+	{"local0", LOG_LOCAL0, false},
+	{"local1", LOG_LOCAL1, false},
+	{"local2", LOG_LOCAL2, false},
+	{"local3", LOG_LOCAL3, false},
+	{"local4", LOG_LOCAL4, false},
+	{"local5", LOG_LOCAL5, false},
+	{"local6", LOG_LOCAL6, false},
+	{"local7", LOG_LOCAL7, false},
+#else
+	{"none", 0, false},
+#endif
+	{NULL, 0}
+};
+
+static const struct config_enum_entry track_function_options[] = {
+	{"none", TRACK_FUNC_OFF, false},
+	{"pl", TRACK_FUNC_PL, false},
+	{"all", TRACK_FUNC_ALL, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(track_function_options) == (TRACK_FUNC_ALL + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry xmlbinary_options[] = {
+	{"base64", XMLBINARY_BASE64, false},
+	{"hex", XMLBINARY_HEX, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(xmlbinary_options) == (XMLBINARY_HEX + 2),
+				 "array length mismatch");
+
+static const struct config_enum_entry xmloption_options[] = {
+	{"content", XMLOPTION_CONTENT, false},
+	{"document", XMLOPTION_DOCUMENT, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(xmloption_options) == (XMLOPTION_CONTENT + 2),
+				 "array length mismatch");
+
+/*
+ * Although only "on", "off", and "safe_encoding" are documented, we
+ * accept all the likely variants of "on" and "off".
+ */
+static const struct config_enum_entry backslash_quote_options[] = {
+	{"safe_encoding", BACKSLASH_QUOTE_SAFE_ENCODING, false},
+	{"on", BACKSLASH_QUOTE_ON, false},
+	{"off", BACKSLASH_QUOTE_OFF, false},
+	{"true", BACKSLASH_QUOTE_ON, true},
+	{"false", BACKSLASH_QUOTE_OFF, true},
+	{"yes", BACKSLASH_QUOTE_ON, true},
+	{"no", BACKSLASH_QUOTE_OFF, true},
+	{"1", BACKSLASH_QUOTE_ON, true},
+	{"0", BACKSLASH_QUOTE_OFF, true},
+	{NULL, 0, false}
+};
+
+/*
+ * Although only "on", "off", and "auto" are documented, we accept
+ * all the likely variants of "on" and "off".
+ */
+static const struct config_enum_entry compute_query_id_options[] = {
+	{"auto", COMPUTE_QUERY_ID_AUTO, false},
+	{"regress", COMPUTE_QUERY_ID_REGRESS, false},
+	{"on", COMPUTE_QUERY_ID_ON, false},
+	{"off", COMPUTE_QUERY_ID_OFF, false},
+	{"true", COMPUTE_QUERY_ID_ON, true},
+	{"false", COMPUTE_QUERY_ID_OFF, true},
+	{"yes", COMPUTE_QUERY_ID_ON, true},
+	{"no", COMPUTE_QUERY_ID_OFF, true},
+	{"1", COMPUTE_QUERY_ID_ON, true},
+	{"0", COMPUTE_QUERY_ID_OFF, true},
+	{NULL, 0, false}
+};
+
+/*
+ * Although only "on", "off", and "partition" are documented, we
+ * accept all the likely variants of "on" and "off".
+ */
+static const struct config_enum_entry constraint_exclusion_options[] = {
+	{"partition", CONSTRAINT_EXCLUSION_PARTITION, false},
+	{"on", CONSTRAINT_EXCLUSION_ON, false},
+	{"off", CONSTRAINT_EXCLUSION_OFF, false},
+	{"true", CONSTRAINT_EXCLUSION_ON, true},
+	{"false", CONSTRAINT_EXCLUSION_OFF, true},
+	{"yes", CONSTRAINT_EXCLUSION_ON, true},
+	{"no", CONSTRAINT_EXCLUSION_OFF, true},
+	{"1", CONSTRAINT_EXCLUSION_ON, true},
+	{"0", CONSTRAINT_EXCLUSION_OFF, true},
+	{NULL, 0, false}
+};
+
+/*
+ * Although only "on", "off", "remote_apply", "remote_write", and "local" are
+ * documented, we accept all the likely variants of "on" and "off".
+ */
+static const struct config_enum_entry synchronous_commit_options[] = {
+	{"local", SYNCHRONOUS_COMMIT_LOCAL_FLUSH, false},
+	{"remote_write", SYNCHRONOUS_COMMIT_REMOTE_WRITE, false},
+	{"remote_apply", SYNCHRONOUS_COMMIT_REMOTE_APPLY, false},
+	{"on", SYNCHRONOUS_COMMIT_ON, false},
+	{"off", SYNCHRONOUS_COMMIT_OFF, false},
+	{"true", SYNCHRONOUS_COMMIT_ON, true},
+	{"false", SYNCHRONOUS_COMMIT_OFF, true},
+	{"yes", SYNCHRONOUS_COMMIT_ON, true},
+	{"no", SYNCHRONOUS_COMMIT_OFF, true},
+	{"1", SYNCHRONOUS_COMMIT_ON, true},
+	{"0", SYNCHRONOUS_COMMIT_OFF, true},
+	{NULL, 0, false}
+};
+
+/*
+ * Although only "on", "off", "try" are documented, we accept all the likely
+ * variants of "on" and "off".
+ */
+static const struct config_enum_entry huge_pages_options[] = {
+	{"off", HUGE_PAGES_OFF, false},
+	{"on", HUGE_PAGES_ON, false},
+	{"try", HUGE_PAGES_TRY, false},
+	{"true", HUGE_PAGES_ON, true},
+	{"false", HUGE_PAGES_OFF, true},
+	{"yes", HUGE_PAGES_ON, true},
+	{"no", HUGE_PAGES_OFF, true},
+	{"1", HUGE_PAGES_ON, true},
+	{"0", HUGE_PAGES_OFF, true},
+	{NULL, 0, false}
+};
+
+static const struct config_enum_entry force_parallel_mode_options[] = {
+	{"off", FORCE_PARALLEL_OFF, false},
+	{"on", FORCE_PARALLEL_ON, false},
+	{"regress", FORCE_PARALLEL_REGRESS, false},
+	{"true", FORCE_PARALLEL_ON, true},
+	{"false", FORCE_PARALLEL_OFF, true},
+	{"yes", FORCE_PARALLEL_ON, true},
+	{"no", FORCE_PARALLEL_OFF, true},
+	{"1", FORCE_PARALLEL_ON, true},
+	{"0", FORCE_PARALLEL_OFF, true},
+	{NULL, 0, false}
+};
+
+static const struct config_enum_entry plan_cache_mode_options[] = {
+	{"auto", PLAN_CACHE_MODE_AUTO, false},
+	{"force_generic_plan", PLAN_CACHE_MODE_FORCE_GENERIC_PLAN, false},
+	{"force_custom_plan", PLAN_CACHE_MODE_FORCE_CUSTOM_PLAN, false},
+	{NULL, 0, false}
+};
+
+static const struct config_enum_entry password_encryption_options[] = {
+	{"md5", PASSWORD_TYPE_MD5, false},
+	{"scram-sha-256", PASSWORD_TYPE_SCRAM_SHA_256, false},
+	{NULL, 0, false}
+};
+
+const struct config_enum_entry ssl_protocol_versions_info[] = {
+	{"", PG_TLS_ANY, false},
+	{"TLSv1", PG_TLS1_VERSION, false},
+	{"TLSv1.1", PG_TLS1_1_VERSION, false},
+	{"TLSv1.2", PG_TLS1_2_VERSION, false},
+	{"TLSv1.3", PG_TLS1_3_VERSION, false},
+	{NULL, 0, false}
+};
+
+StaticAssertDecl(lengthof(ssl_protocol_versions_info) == (PG_TLS1_3_VERSION + 2),
+				 "array length mismatch");
+
+static struct config_enum_entry recovery_init_sync_method_options[] = {
+	{"fsync", RECOVERY_INIT_SYNC_METHOD_FSYNC, false},
+#ifdef HAVE_SYNCFS
+	{"syncfs", RECOVERY_INIT_SYNC_METHOD_SYNCFS, false},
+#endif
+	{NULL, 0, false}
+};
+
+static struct config_enum_entry shared_memory_options[] = {
+#ifndef WIN32
+	{"sysv", SHMEM_TYPE_SYSV, false},
+#endif
+#ifndef EXEC_BACKEND
+	{"mmap", SHMEM_TYPE_MMAP, false},
+#endif
+#ifdef WIN32
+	{"windows", SHMEM_TYPE_WINDOWS, false},
+#endif
+	{NULL, 0, false}
+};
+
+static struct config_enum_entry default_toast_compression_options[] = {
+	{"pglz", TOAST_PGLZ_COMPRESSION, false},
+#ifdef  USE_LZ4
+	{"lz4", TOAST_LZ4_COMPRESSION, false},
+#endif
+	{NULL, 0, false}
+};
+
+/*
+ * Options for enum values stored in other modules
+ */
+extern const struct config_enum_entry wal_level_options[];
+extern const struct config_enum_entry archive_mode_options[];
+extern const struct config_enum_entry recovery_target_action_options[];
+extern const struct config_enum_entry sync_method_options[];
+extern const struct config_enum_entry dynamic_shared_memory_options[];
+
+/*
+ * GUC option variables that are exported from this module
+ */
+bool		log_duration = false;
+bool		Debug_print_plan = false;
+bool		Debug_print_parse = false;
+bool		Debug_print_rewritten = false;
+bool		Debug_pretty_print = true;
+
+bool		log_parser_stats = false;
+bool		log_planner_stats = false;
+bool		log_executor_stats = false;
+bool		log_statement_stats = false;	/* this is sort of all three above
+											 * together */
+bool		log_btree_build_stats = false;
+char	   *event_source;
+
+bool		row_security;
+bool		check_function_bodies = true;
+
+/*
+ * This GUC exists solely for backward compatibility, check its definition for
+ * details.
+ */
+bool		default_with_oids = false;
+bool		session_auth_is_superuser;
+
+int			log_min_error_statement = ERROR;
+int			log_min_messages = WARNING;
+int			client_min_messages = NOTICE;
+int			log_min_duration_sample = -1;
+int			log_min_duration_statement = -1;
+int			log_parameter_max_length = -1;
+int			log_parameter_max_length_on_error = 0;
+int			log_temp_files = -1;
+double		log_statement_sample_rate = 1.0;
+double		log_xact_sample_rate = 0;
+int			trace_recovery_messages = LOG;
+char	   *backtrace_functions;
+char	   *backtrace_symbol_list;
+
+int			temp_file_limit = -1;
+
+int			num_temp_buffers = 1024;
+
+char	   *cluster_name = "";
+char	   *ConfigFileName;
+char	   *HbaFileName;
+char	   *IdentFileName;
+char	   *external_pid_file;
+
+char	   *pgstat_temp_directory;
+
+char	   *application_name;
+
+int			tcp_keepalives_idle;
+int			tcp_keepalives_interval;
+int			tcp_keepalives_count;
+int			tcp_user_timeout;
+
+/*
+ * SSL renegotiation was been removed in PostgreSQL 9.5, but we tolerate it
+ * being set to zero (meaning never renegotiate) for backward compatibility.
+ * This avoids breaking compatibility with clients that have never supported
+ * renegotiation and therefore always try to zero it.
+ */
+int			ssl_renegotiation_limit;
+
+/*
+ * This really belongs in pg_shmem.c, but is defined here so that it doesn't
+ * need to be duplicated in all the different implementations of pg_shmem.c.
+ */
+int			huge_pages;
+int			huge_page_size;
+
+/*
+ * These variables are all dummies that don't do anything, except in some
+ * cases provide the value for SHOW to display.  The real state is elsewhere
+ * and is kept in sync by assign_hooks.
+ */
+static char *syslog_ident_str;
+static double phony_random_seed;
+static char *client_encoding_string;
+static char *datestyle_string;
+static char *locale_collate;
+static char *locale_ctype;
+static char *server_encoding_string;
+static char *server_version_string;
+static int	server_version_num;
+static char *timezone_string;
+static char *log_timezone_string;
+static char *timezone_abbreviations_string;
+static char *data_directory;
+static char *session_authorization_string;
+static int	max_function_args;
+static int	max_index_keys;
+static int	max_identifier_length;
+static int	block_size;
+static int	segment_size;
+static int	wal_block_size;
+static bool data_checksums;
+static bool integer_datetimes;
+static bool assert_enabled;
+static bool in_hot_standby;
+static char *recovery_target_timeline_string;
+static char *recovery_target_string;
+static char *recovery_target_xid_string;
+static char *recovery_target_name_string;
+static char *recovery_target_lsn_string;
+
+
+/* should be static, but commands/variable.c needs to get at this */
+char	   *role_string;
+
+
+/*
+ * Displayable names for context types (enum GucContext)
+ *
+ * Note: these strings are deliberately not localized.
+ */
+const char *const GucContext_Names[] =
+{
+	 /* PGC_INTERNAL */ "internal",
+	 /* PGC_POSTMASTER */ "postmaster",
+	 /* PGC_SIGHUP */ "sighup",
+	 /* PGC_SU_BACKEND */ "superuser-backend",
+	 /* PGC_BACKEND */ "backend",
+	 /* PGC_SUSET */ "superuser",
+	 /* PGC_USERSET */ "user"
+};
+
+StaticAssertDecl(lengthof(GucContext_Names) == (PGC_USERSET + 1),
+				 "array length mismatch");
+
+/*
+ * Displayable names for source types (enum GucSource)
+ *
+ * Note: these strings are deliberately not localized.
+ */
+const char *const GucSource_Names[] =
+{
+	 /* PGC_S_DEFAULT */ "default",
+	 /* PGC_S_DYNAMIC_DEFAULT */ "default",
+	 /* PGC_S_ENV_VAR */ "environment variable",
+	 /* PGC_S_FILE */ "configuration file",
+	 /* PGC_S_ARGV */ "command line",
+	 /* PGC_S_GLOBAL */ "global",
+	 /* PGC_S_DATABASE */ "database",
+	 /* PGC_S_USER */ "user",
+	 /* PGC_S_DATABASE_USER */ "database user",
+	 /* PGC_S_CLIENT */ "client",
+	 /* PGC_S_OVERRIDE */ "override",
+	 /* PGC_S_INTERACTIVE */ "interactive",
+	 /* PGC_S_TEST */ "test",
+	 /* PGC_S_SESSION */ "session"
+};
+
+StaticAssertDecl(lengthof(GucSource_Names) == (PGC_S_SESSION + 1),
+				 "array length mismatch");
+
+/*
+ * Displayable names for the groupings defined in enum config_group
+ */
+const char *const config_group_names[] =
+{
+	/* UNGROUPED */
+	gettext_noop("Ungrouped"),
+	/* FILE_LOCATIONS */
+	gettext_noop("File Locations"),
+	/* CONN_AUTH_SETTINGS */
+	gettext_noop("Connections and Authentication / Connection Settings"),
+	/* CONN_AUTH_AUTH */
+	gettext_noop("Connections and Authentication / Authentication"),
+	/* CONN_AUTH_SSL */
+	gettext_noop("Connections and Authentication / SSL"),
+	/* RESOURCES_MEM */
+	gettext_noop("Resource Usage / Memory"),
+	/* RESOURCES_DISK */
+	gettext_noop("Resource Usage / Disk"),
+	/* RESOURCES_KERNEL */
+	gettext_noop("Resource Usage / Kernel Resources"),
+	/* RESOURCES_VACUUM_DELAY */
+	gettext_noop("Resource Usage / Cost-Based Vacuum Delay"),
+	/* RESOURCES_BGWRITER */
+	gettext_noop("Resource Usage / Background Writer"),
+	/* RESOURCES_ASYNCHRONOUS */
+	gettext_noop("Resource Usage / Asynchronous Behavior"),
+	/* WAL_SETTINGS */
+	gettext_noop("Write-Ahead Log / Settings"),
+	/* WAL_CHECKPOINTS */
+	gettext_noop("Write-Ahead Log / Checkpoints"),
+	/* WAL_ARCHIVING */
+	gettext_noop("Write-Ahead Log / Archiving"),
+	/* WAL_ARCHIVE_RECOVERY */
+	gettext_noop("Write-Ahead Log / Archive Recovery"),
+	/* WAL_RECOVERY_TARGET */
+	gettext_noop("Write-Ahead Log / Recovery Target"),
+	/* REPLICATION_SENDING */
+	gettext_noop("Replication / Sending Servers"),
+	/* REPLICATION_PRIMARY */
+	gettext_noop("Replication / Primary Server"),
+	/* REPLICATION_STANDBY */
+	gettext_noop("Replication / Standby Servers"),
+	/* REPLICATION_SUBSCRIBERS */
+	gettext_noop("Replication / Subscribers"),
+	/* QUERY_TUNING_METHOD */
+	gettext_noop("Query Tuning / Planner Method Configuration"),
+	/* QUERY_TUNING_COST */
+	gettext_noop("Query Tuning / Planner Cost Constants"),
+	/* QUERY_TUNING_GEQO */
+	gettext_noop("Query Tuning / Genetic Query Optimizer"),
+	/* QUERY_TUNING_OTHER */
+	gettext_noop("Query Tuning / Other Planner Options"),
+	/* LOGGING_WHERE */
+	gettext_noop("Reporting and Logging / Where to Log"),
+	/* LOGGING_WHEN */
+	gettext_noop("Reporting and Logging / When to Log"),
+	/* LOGGING_WHAT */
+	gettext_noop("Reporting and Logging / What to Log"),
+	/* PROCESS_TITLE */
+	gettext_noop("Reporting and Logging / Process Title"),
+	/* STATS_MONITORING */
+	gettext_noop("Statistics / Monitoring"),
+	/* STATS_COLLECTOR */
+	gettext_noop("Statistics / Query and Index Statistics Collector"),
+	/* AUTOVACUUM */
+	gettext_noop("Autovacuum"),
+	/* CLIENT_CONN_STATEMENT */
+	gettext_noop("Client Connection Defaults / Statement Behavior"),
+	/* CLIENT_CONN_LOCALE */
+	gettext_noop("Client Connection Defaults / Locale and Formatting"),
+	/* CLIENT_CONN_PRELOAD */
+	gettext_noop("Client Connection Defaults / Shared Library Preloading"),
+	/* CLIENT_CONN_OTHER */
+	gettext_noop("Client Connection Defaults / Other Defaults"),
+	/* LOCK_MANAGEMENT */
+	gettext_noop("Lock Management"),
+	/* COMPAT_OPTIONS_PREVIOUS */
+	gettext_noop("Version and Platform Compatibility / Previous PostgreSQL Versions"),
+	/* COMPAT_OPTIONS_CLIENT */
+	gettext_noop("Version and Platform Compatibility / Other Platforms and Clients"),
+	/* ERROR_HANDLING */
+	gettext_noop("Error Handling"),
+	/* PRESET_OPTIONS */
+	gettext_noop("Preset Options"),
+	/* CUSTOM_OPTIONS */
+	gettext_noop("Customized Options"),
+	/* DEVELOPER_OPTIONS */
+	gettext_noop("Developer Options"),
+	/* help_config wants this array to be null-terminated */
+	NULL
+};
+
+StaticAssertDecl(lengthof(config_group_names) == (DEVELOPER_OPTIONS + 2),
+				 "array length mismatch");
+
+/*
+ * Displayable names for GUC variable types (enum config_type)
+ *
+ * Note: these strings are deliberately not localized.
+ */
+const char *const config_type_names[] =
+{
+	 /* PGC_BOOL */ "bool",
+	 /* PGC_INT */ "integer",
+	 /* PGC_REAL */ "real",
+	 /* PGC_STRING */ "string",
+	 /* PGC_ENUM */ "enum"
+};
+
+StaticAssertDecl(lengthof(config_type_names) == (PGC_ENUM + 1),
+				 "array length mismatch");
+
+/*
+ * Unit conversion tables.
+ *
+ * There are two tables, one for memory units, and another for time units.
+ * For each supported conversion from one unit to another, we have an entry
+ * in the table.
+ *
+ * To keep things simple, and to avoid possible roundoff error,
+ * conversions are never chained.  There needs to be a direct conversion
+ * between all units (of the same type).
+ *
+ * The conversions for each base unit must be kept in order from greatest to
+ * smallest human-friendly unit; convert_xxx_from_base_unit() rely on that.
+ * (The order of the base-unit groups does not matter.)
+ */
+#define MAX_UNIT_LEN		3	/* length of longest recognized unit string */
+
+typedef struct
+{
+	char		unit[MAX_UNIT_LEN + 1]; /* unit, as a string, like "kB" or
+										 * "min" */
+	int			base_unit;		/* GUC_UNIT_XXX */
+	double		multiplier;		/* Factor for converting unit -> base_unit */
+} unit_conversion;
+
+/* Ensure that the constants in the tables don't overflow or underflow */
+#if BLCKSZ < 1024 || BLCKSZ > (1024*1024)
+#error BLCKSZ must be between 1KB and 1MB
+#endif
+#if XLOG_BLCKSZ < 1024 || XLOG_BLCKSZ > (1024*1024)
+#error XLOG_BLCKSZ must be between 1KB and 1MB
+#endif
+
+static const char *memory_units_hint = gettext_noop("Valid units for this parameter are \"B\", \"kB\", \"MB\", \"GB\", and \"TB\".");
+
+static const unit_conversion memory_unit_conversion_table[] =
+{
+	{"TB", GUC_UNIT_BYTE, 1024.0 * 1024.0 * 1024.0 * 1024.0},
+	{"GB", GUC_UNIT_BYTE, 1024.0 * 1024.0 * 1024.0},
+	{"MB", GUC_UNIT_BYTE, 1024.0 * 1024.0},
+	{"kB", GUC_UNIT_BYTE, 1024.0},
+	{"B", GUC_UNIT_BYTE, 1.0},
+
+	{"TB", GUC_UNIT_KB, 1024.0 * 1024.0 * 1024.0},
+	{"GB", GUC_UNIT_KB, 1024.0 * 1024.0},
+	{"MB", GUC_UNIT_KB, 1024.0},
+	{"kB", GUC_UNIT_KB, 1.0},
+	{"B", GUC_UNIT_KB, 1.0 / 1024.0},
+
+	{"TB", GUC_UNIT_MB, 1024.0 * 1024.0},
+	{"GB", GUC_UNIT_MB, 1024.0},
+	{"MB", GUC_UNIT_MB, 1.0},
+	{"kB", GUC_UNIT_MB, 1.0 / 1024.0},
+	{"B", GUC_UNIT_MB, 1.0 / (1024.0 * 1024.0)},
+
+	{"TB", GUC_UNIT_BLOCKS, (1024.0 * 1024.0 * 1024.0) / (BLCKSZ / 1024)},
+	{"GB", GUC_UNIT_BLOCKS, (1024.0 * 1024.0) / (BLCKSZ / 1024)},
+	{"MB", GUC_UNIT_BLOCKS, 1024.0 / (BLCKSZ / 1024)},
+	{"kB", GUC_UNIT_BLOCKS, 1.0 / (BLCKSZ / 1024)},
+	{"B", GUC_UNIT_BLOCKS, 1.0 / BLCKSZ},
+
+	{"TB", GUC_UNIT_XBLOCKS, (1024.0 * 1024.0 * 1024.0) / (XLOG_BLCKSZ / 1024)},
+	{"GB", GUC_UNIT_XBLOCKS, (1024.0 * 1024.0) / (XLOG_BLCKSZ / 1024)},
+	{"MB", GUC_UNIT_XBLOCKS, 1024.0 / (XLOG_BLCKSZ / 1024)},
+	{"kB", GUC_UNIT_XBLOCKS, 1.0 / (XLOG_BLCKSZ / 1024)},
+	{"B", GUC_UNIT_XBLOCKS, 1.0 / XLOG_BLCKSZ},
+
+	{""}						/* end of table marker */
+};
+
+static const char *time_units_hint = gettext_noop("Valid units for this parameter are \"us\", \"ms\", \"s\", \"min\", \"h\", and \"d\".");
+
+static const unit_conversion time_unit_conversion_table[] =
+{
+	{"d", GUC_UNIT_MS, 1000 * 60 * 60 * 24},
+	{"h", GUC_UNIT_MS, 1000 * 60 * 60},
+	{"min", GUC_UNIT_MS, 1000 * 60},
+	{"s", GUC_UNIT_MS, 1000},
+	{"ms", GUC_UNIT_MS, 1},
+	{"us", GUC_UNIT_MS, 1.0 / 1000},
+
+	{"d", GUC_UNIT_S, 60 * 60 * 24},
+	{"h", GUC_UNIT_S, 60 * 60},
+	{"min", GUC_UNIT_S, 60},
+	{"s", GUC_UNIT_S, 1},
+	{"ms", GUC_UNIT_S, 1.0 / 1000},
+	{"us", GUC_UNIT_S, 1.0 / (1000 * 1000)},
+
+	{"d", GUC_UNIT_MIN, 60 * 24},
+	{"h", GUC_UNIT_MIN, 60},
+	{"min", GUC_UNIT_MIN, 1},
+	{"s", GUC_UNIT_MIN, 1.0 / 60},
+	{"ms", GUC_UNIT_MIN, 1.0 / (1000 * 60)},
+	{"us", GUC_UNIT_MIN, 1.0 / (1000 * 1000 * 60)},
+
+	{""}						/* end of table marker */
+};
+
+/*
+ * Contents of GUC tables
+ *
+ * See src/backend/utils/misc/README for design notes.
+ *
+ * TO ADD AN OPTION:
+ *
+ * 1. Declare a global variable of type bool, int, double, or char*
+ *	  and make use of it.
+ *
+ * 2. Decide at what times it's safe to set the option. See guc.h for
+ *	  details.
+ *
+ * 3. Decide on a name, a default value, upper and lower bounds (if
+ *	  applicable), etc.
+ *
+ * 4. Add a record below.
+ *
+ * 5. Add it to src/backend/utils/misc/postgresql.conf.sample, if
+ *	  appropriate.
+ *
+ * 6. Don't forget to document the option (at least in config.sgml).
+ *
+ * 7. If it's a new GUC_LIST_QUOTE option, you must add it to
+ *	  variable_is_guc_list_quote() in src/bin/pg_dump/dumputils.c.
+ */
+
+
+/******** option records follow ********/
+
+static struct config_bool ConfigureNamesBool[] =
+{
+	{
+		{"enable_seqscan", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of sequential-scan plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_seqscan,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_indexscan", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of index-scan plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_indexscan,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_indexonlyscan", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of index-only-scan plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_indexonlyscan,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_bitmapscan", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of bitmap-scan plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_bitmapscan,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_tidscan", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of TID scan plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_tidscan,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_sort", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of explicit sort steps."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_sort,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_incremental_sort", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of incremental sort steps."),
+			NULL
+		},
+		&enable_incremental_sort,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_hashagg", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of hashed aggregation plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_hashagg,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_material", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of materialization."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_material,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_memoize", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of memoization."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_memoize,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_nestloop", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of nested-loop join plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_nestloop,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_mergejoin", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of merge join plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_mergejoin,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_hashjoin", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of hash join plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_hashjoin,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_gathermerge", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of gather merge plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_gathermerge,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_partitionwise_join", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables partitionwise join."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_partitionwise_join,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_partitionwise_aggregate", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables partitionwise aggregation and grouping."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_partitionwise_aggregate,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_parallel_append", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of parallel append plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_parallel_append,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_parallel_hash", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of parallel hash plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_parallel_hash,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_partition_pruning", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables plan-time and execution-time partition pruning."),
+			gettext_noop("Allows the query planner and executor to compare partition "
+						 "bounds to conditions in the query to determine which "
+						 "partitions must be scanned."),
+			GUC_EXPLAIN
+		},
+		&enable_partition_pruning,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"enable_async_append", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enables the planner's use of async append plans."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&enable_async_append,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("Enables genetic query optimization."),
+			gettext_noop("This algorithm attempts to do planning without "
+						 "exhaustive searching."),
+			GUC_EXPLAIN
+		},
+		&enable_geqo,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		/* Not for general use --- used by SET SESSION AUTHORIZATION */
+		{"is_superuser", PGC_INTERNAL, UNGROUPED,
+			gettext_noop("Shows whether the current user is a superuser."),
+			NULL,
+			GUC_REPORT | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&session_auth_is_superuser,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"bonjour", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Enables advertising the server via Bonjour."),
+			NULL
+		},
+		&enable_bonjour,
+		false,
+		check_bonjour, NULL, NULL
+	},
+	{
+		{"track_commit_timestamp", PGC_POSTMASTER, REPLICATION_SENDING,
+			gettext_noop("Collects transaction commit time."),
+			NULL
+		},
+		&track_commit_timestamp,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"ssl", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Enables SSL connections."),
+			NULL
+		},
+		&EnableSSL,
+		false,
+		check_ssl, NULL, NULL
+	},
+	{
+		{"ssl_passphrase_command_supports_reload", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Also use ssl_passphrase_command during server reload."),
+			NULL
+		},
+		&ssl_passphrase_command_supports_reload,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"ssl_prefer_server_ciphers", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Give priority to server ciphersuite order."),
+			NULL
+		},
+		&SSLPreferServerCiphers,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"fsync", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Forces synchronization of updates to disk."),
+			gettext_noop("The server will use the fsync() system call in several places to make "
+						 "sure that updates are physically written to disk. This insures "
+						 "that a database cluster will recover to a consistent state after "
+						 "an operating system or hardware crash.")
+		},
+		&enableFsync,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"ignore_checksum_failure", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Continues processing after a checksum failure."),
+			gettext_noop("Detection of a checksum failure normally causes PostgreSQL to "
+						 "report an error, aborting the current transaction. Setting "
+						 "ignore_checksum_failure to true causes the system to ignore the failure "
+						 "(but still report a warning), and continue processing. This "
+						 "behavior could cause crashes or other serious problems. Only "
+						 "has an effect if checksums are enabled."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&ignore_checksum_failure,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"zero_damaged_pages", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Continues processing past damaged page headers."),
+			gettext_noop("Detection of a damaged page header normally causes PostgreSQL to "
+						 "report an error, aborting the current transaction. Setting "
+						 "zero_damaged_pages to true causes the system to instead report a "
+						 "warning, zero out the damaged page, and continue processing. This "
+						 "behavior will destroy data, namely all the rows on the damaged page."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&zero_damaged_pages,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"ignore_invalid_pages", PGC_POSTMASTER, DEVELOPER_OPTIONS,
+			gettext_noop("Continues recovery after an invalid pages failure."),
+			gettext_noop("Detection of WAL records having references to "
+						 "invalid pages during recovery causes PostgreSQL to "
+						 "raise a PANIC-level error, aborting the recovery. "
+						 "Setting ignore_invalid_pages to true causes "
+						 "the system to ignore invalid page references "
+						 "in WAL records (but still report a warning), "
+						 "and continue recovery. This behavior may cause "
+						 "crashes, data loss, propagate or hide corruption, "
+						 "or other serious problems. Only has an effect "
+						 "during recovery or in standby mode."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&ignore_invalid_pages,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"full_page_writes", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Writes full pages to WAL when first modified after a checkpoint."),
+			gettext_noop("A page write in process during an operating system crash might be "
+						 "only partially written to disk.  During recovery, the row changes "
+						 "stored in WAL are not enough to recover.  This option writes "
+						 "pages when first modified after a checkpoint to WAL so full recovery "
+						 "is possible.")
+		},
+		&fullPageWrites,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_log_hints", PGC_POSTMASTER, WAL_SETTINGS,
+			gettext_noop("Writes full pages to WAL when first modified after a checkpoint, even for a non-critical modification."),
+			NULL
+		},
+		&wal_log_hints,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_compression", PGC_SUSET, WAL_SETTINGS,
+			gettext_noop("Compresses full-page writes written in WAL file."),
+			NULL
+		},
+		&wal_compression,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_init_zero", PGC_SUSET, WAL_SETTINGS,
+			gettext_noop("Writes zeroes to new WAL files before first use."),
+			NULL
+		},
+		&wal_init_zero,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_recycle", PGC_SUSET, WAL_SETTINGS,
+			gettext_noop("Recycles WAL files by renaming them."),
+			NULL
+		},
+		&wal_recycle,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_checkpoints", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Logs each checkpoint."),
+			NULL
+		},
+		&log_checkpoints,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_connections", PGC_SU_BACKEND, LOGGING_WHAT,
+			gettext_noop("Logs each successful connection."),
+			NULL
+		},
+		&Log_connections,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_disconnections", PGC_SU_BACKEND, LOGGING_WHAT,
+			gettext_noop("Logs end of a session, including duration."),
+			NULL
+		},
+		&Log_disconnections,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_replication_commands", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Logs each replication command."),
+			NULL
+		},
+		&log_replication_commands,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_assertions", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether the running server has assertion checks enabled."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&assert_enabled,
+#ifdef USE_ASSERT_CHECKING
+		true,
+#else
+		false,
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"exit_on_error", PGC_USERSET, ERROR_HANDLING_OPTIONS,
+			gettext_noop("Terminate session on any error."),
+			NULL
+		},
+		&ExitOnAnyError,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"restart_after_crash", PGC_SIGHUP, ERROR_HANDLING_OPTIONS,
+			gettext_noop("Reinitialize server after backend crash."),
+			NULL
+		},
+		&restart_after_crash,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"remove_temp_files_after_crash", PGC_SIGHUP, DEVELOPER_OPTIONS,
+			gettext_noop("Remove temporary files after backend crash."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&remove_temp_files_after_crash,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_duration", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Logs the duration of each completed SQL statement."),
+			NULL
+		},
+		&log_duration,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_print_parse", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("Logs each query's parse tree."),
+			NULL
+		},
+		&Debug_print_parse,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_print_rewritten", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("Logs each query's rewritten parse tree."),
+			NULL
+		},
+		&Debug_print_rewritten,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_print_plan", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("Logs each query's execution plan."),
+			NULL
+		},
+		&Debug_print_plan,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_pretty_print", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("Indents parse and plan tree displays."),
+			NULL
+		},
+		&Debug_pretty_print,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_parser_stats", PGC_SUSET, STATS_MONITORING,
+			gettext_noop("Writes parser performance statistics to the server log."),
+			NULL
+		},
+		&log_parser_stats,
+		false,
+		check_stage_log_stats, NULL, NULL
+	},
+	{
+		{"log_planner_stats", PGC_SUSET, STATS_MONITORING,
+			gettext_noop("Writes planner performance statistics to the server log."),
+			NULL
+		},
+		&log_planner_stats,
+		false,
+		check_stage_log_stats, NULL, NULL
+	},
+	{
+		{"log_executor_stats", PGC_SUSET, STATS_MONITORING,
+			gettext_noop("Writes executor performance statistics to the server log."),
+			NULL
+		},
+		&log_executor_stats,
+		false,
+		check_stage_log_stats, NULL, NULL
+	},
+	{
+		{"log_statement_stats", PGC_SUSET, STATS_MONITORING,
+			gettext_noop("Writes cumulative performance statistics to the server log."),
+			NULL
+		},
+		&log_statement_stats,
+		false,
+		check_log_stats, NULL, NULL
+	},
+#ifdef BTREE_BUILD_STATS
+	{
+		{"log_btree_build_stats", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Logs system resource usage statistics (memory and CPU) on various B-tree operations."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&log_btree_build_stats,
+		false,
+		NULL, NULL, NULL
+	},
+#endif
+
+	{
+		{"track_activities", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects information about executing commands."),
+			gettext_noop("Enables the collection of information on the currently "
+						 "executing command of each session, along with "
+						 "the time at which that command began execution.")
+		},
+		&pgstat_track_activities,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"track_counts", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects statistics on database activity."),
+			NULL
+		},
+		&pgstat_track_counts,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"track_io_timing", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects timing statistics for database I/O activity."),
+			NULL
+		},
+		&track_io_timing,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"track_wal_io_timing", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects timing statistics for WAL I/O activity."),
+			NULL
+		},
+		&track_wal_io_timing,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"update_process_title", PGC_SUSET, PROCESS_TITLE,
+			gettext_noop("Updates the process title to show the active SQL command."),
+			gettext_noop("Enables updating of the process title every time a new SQL command is received by the server.")
+		},
+		&update_process_title,
+#ifdef WIN32
+		false,
+#else
+		true,
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Starts the autovacuum subprocess."),
+			NULL
+		},
+		&autovacuum_start_daemon,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"trace_notify", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Generates debugging output for LISTEN and NOTIFY."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_notify,
+		false,
+		NULL, NULL, NULL
+	},
+
+#ifdef LOCK_DEBUG
+	{
+		{"trace_locks", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emits information about lock usage."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_locks,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"trace_userlocks", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emits information about user lock usage."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_userlocks,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"trace_lwlocks", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emits information about lightweight lock usage."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_lwlocks,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"debug_deadlocks", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Dumps information about all current locks when a deadlock timeout occurs."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Debug_deadlocks,
+		false,
+		NULL, NULL, NULL
+	},
+#endif
+
+	{
+		{"log_lock_waits", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Logs long lock waits."),
+			NULL
+		},
+		&log_lock_waits,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_recovery_conflict_waits", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Logs standby recovery conflict waits."),
+			NULL
+		},
+		&log_recovery_conflict_waits,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_hostname", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Logs the host name in the connection logs."),
+			gettext_noop("By default, connection logs only show the IP address "
+						 "of the connecting host. If you want them to show the host name you "
+						 "can turn this on, but depending on your host name resolution "
+						 "setup it might impose a non-negligible performance penalty.")
+		},
+		&log_hostname,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"transform_null_equals", PGC_USERSET, COMPAT_OPTIONS_CLIENT,
+			gettext_noop("Treats \"expr=NULL\" as \"expr IS NULL\"."),
+			gettext_noop("When turned on, expressions of the form expr = NULL "
+						 "(or NULL = expr) are treated as expr IS NULL, that is, they "
+						 "return true if expr evaluates to the null value, and false "
+						 "otherwise. The correct behavior of expr = NULL is to always "
+						 "return null (unknown).")
+		},
+		&Transform_null_equals,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"db_user_namespace", PGC_SIGHUP, CONN_AUTH_AUTH,
+			gettext_noop("Enables per-database user names."),
+			NULL
+		},
+		&Db_user_namespace,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"default_transaction_read_only", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the default read-only status of new transactions."),
+			NULL,
+			GUC_REPORT
+		},
+		&DefaultXactReadOnly,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"transaction_read_only", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the current transaction's read-only status."),
+			NULL,
+			GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&XactReadOnly,
+		false,
+		check_transaction_read_only, NULL, NULL
+	},
+	{
+		{"default_transaction_deferrable", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the default deferrable status of new transactions."),
+			NULL
+		},
+		&DefaultXactDeferrable,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"transaction_deferrable", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Whether to defer a read-only serializable transaction until it can be executed with no possible serialization failures."),
+			NULL,
+			GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&XactDeferrable,
+		false,
+		check_transaction_deferrable, NULL, NULL
+	},
+	{
+		{"row_security", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Enable row security."),
+			gettext_noop("When enabled, row security will be applied to all users.")
+		},
+		&row_security,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"check_function_bodies", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Check routine bodies during CREATE FUNCTION and CREATE PROCEDURE."),
+			NULL
+		},
+		&check_function_bodies,
+		true,
+		NULL, NULL, NULL
+	},
+	{
+		{"array_nulls", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Enable input of NULL elements in arrays."),
+			gettext_noop("When turned on, unquoted NULL in an array input "
+						 "value means a null value; "
+						 "otherwise it is taken literally.")
+		},
+		&Array_nulls,
+		true,
+		NULL, NULL, NULL
+	},
+
+	/*
+	 * WITH OIDS support, and consequently default_with_oids, was removed in
+	 * PostgreSQL 12, but we tolerate the parameter being set to false to
+	 * avoid unnecessarily breaking older dump files.
+	 */
+	{
+		{"default_with_oids", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("WITH OIDS is no longer supported; this can only be false."),
+			NULL,
+			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE
+		},
+		&default_with_oids,
+		false,
+		check_default_with_oids, NULL, NULL
+	},
+	{
+		{"logging_collector", PGC_POSTMASTER, LOGGING_WHERE,
+			gettext_noop("Start a subprocess to capture stderr output and/or csvlogs into log files."),
+			NULL
+		},
+		&Logging_collector,
+		false,
+		NULL, NULL, NULL
+	},
+	{
+		{"log_truncate_on_rotation", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Truncate existing log files of same name during log rotation."),
+			NULL
+		},
+		&Log_truncate_on_rotation,
+		false,
+		NULL, NULL, NULL
+	},
+
+#ifdef TRACE_SORT
+	{
+		{"trace_sort", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emit information about resource usage in sorting."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&trace_sort,
+		false,
+		NULL, NULL, NULL
+	},
+#endif
+
+#ifdef TRACE_SYNCSCAN
+	/* this is undocumented because not exposed in a standard build */
+	{
+		{"trace_syncscan", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Generate debugging output for synchronized scanning."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&trace_syncscan,
+		false,
+		NULL, NULL, NULL
+	},
+#endif
+
+#ifdef DEBUG_BOUNDED_SORT
+	/* this is undocumented because not exposed in a standard build */
+	{
+		{
+			"optimize_bounded_sort", PGC_USERSET, QUERY_TUNING_METHOD,
+			gettext_noop("Enable bounded sorting using heap sort."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_EXPLAIN
+		},
+		&optimize_bounded_sort,
+		true,
+		NULL, NULL, NULL
+	},
+#endif
+
+#ifdef WAL_DEBUG
+	{
+		{"wal_debug", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emit WAL-related debugging output."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&XLOG_DEBUG,
+		false,
+		NULL, NULL, NULL
+	},
+#endif
+
+	{
+		{"integer_datetimes", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether datetimes are integer based."),
+			NULL,
+			GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&integer_datetimes,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"krb_caseins_users", PGC_SIGHUP, CONN_AUTH_AUTH,
+			gettext_noop("Sets whether Kerberos and GSSAPI user names should be treated as case-insensitive."),
+			NULL
+		},
+		&pg_krb_caseins_users,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"escape_string_warning", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Warn about backslash escapes in ordinary string literals."),
+			NULL
+		},
+		&escape_string_warning,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"standard_conforming_strings", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Causes '...' strings to treat backslashes literally."),
+			NULL,
+			GUC_REPORT
+		},
+		&standard_conforming_strings,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"synchronize_seqscans", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Enable synchronized sequential scans."),
+			NULL
+		},
+		&synchronize_seqscans,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_target_inclusive", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets whether to include or exclude transaction with recovery target."),
+			NULL
+		},
+		&recoveryTargetInclusive,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"hot_standby", PGC_POSTMASTER, REPLICATION_STANDBY,
+			gettext_noop("Allows connections and queries during recovery."),
+			NULL
+		},
+		&EnableHotStandby,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"hot_standby_feedback", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Allows feedback from a hot standby to the primary that will avoid query conflicts."),
+			NULL
+		},
+		&hot_standby_feedback,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"in_hot_standby", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether hot standby is currently active."),
+			NULL,
+			GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&in_hot_standby,
+		false,
+		NULL, NULL, show_in_hot_standby
+	},
+
+	{
+		{"allow_system_table_mods", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Allows modifications of the structure of system tables."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&allowSystemTableMods,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ignore_system_indexes", PGC_BACKEND, DEVELOPER_OPTIONS,
+			gettext_noop("Disables reading from system indexes."),
+			gettext_noop("It does not prevent updating the indexes, so it is safe "
+						 "to use.  The worst consequence is slowness."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&IgnoreSystemIndexes,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"allow_in_place_tablespaces", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Allows tablespaces directly inside pg_tblspc, for testing."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&allow_in_place_tablespaces,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"lo_compat_privileges", PGC_SUSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Enables backward compatibility mode for privilege checks on large objects."),
+			gettext_noop("Skips privilege checks when reading or modifying large objects, "
+						 "for compatibility with PostgreSQL releases prior to 9.0.")
+		},
+		&lo_compat_privileges,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"quote_all_identifiers", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("When generating SQL fragments, quote all identifiers."),
+			NULL,
+		},
+		&quote_all_identifiers,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"data_checksums", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether data checksums are turned on for this cluster."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&data_checksums,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"syslog_sequence_numbers", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Add sequence number to syslog messages to avoid duplicate suppression."),
+			NULL
+		},
+		&syslog_sequence_numbers,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"syslog_split_messages", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Split messages sent to syslog by lines and to fit into 1024 bytes."),
+			NULL
+		},
+		&syslog_split_messages,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"parallel_leader_participation", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Controls whether Gather and Gather Merge also run subplans."),
+			gettext_noop("Should gather nodes also run subplans or just gather tuples?"),
+			GUC_EXPLAIN
+		},
+		&parallel_leader_participation,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Allow JIT compilation."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&jit_enabled,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_debugging_support", PGC_SU_BACKEND, DEVELOPER_OPTIONS,
+			gettext_noop("Register JIT-compiled functions with debugger."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_debugging_support,
+		false,
+
+		/*
+		 * This is not guaranteed to be available, but given it's a developer
+		 * oriented option, it doesn't seem worth adding code checking
+		 * availability.
+		 */
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_dump_bitcode", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Write out LLVM bitcode to facilitate JIT debugging."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_dump_bitcode,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_expressions", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Allow JIT compilation of expressions."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_expressions,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_profiling_support", PGC_SU_BACKEND, DEVELOPER_OPTIONS,
+			gettext_noop("Register JIT-compiled functions with perf profiler."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_profiling_support,
+		false,
+
+		/*
+		 * This is not guaranteed to be available, but given it's a developer
+		 * oriented option, it doesn't seem worth adding code checking
+		 * availability.
+		 */
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_tuple_deforming", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Allow JIT compilation of tuple deforming."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_tuple_deforming,
+		true,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"data_sync_retry", PGC_POSTMASTER, ERROR_HANDLING_OPTIONS,
+			gettext_noop("Whether to continue running after a failure to sync data files."),
+		},
+		&data_sync_retry,
+		false,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_receiver_create_temp_slot", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets whether a WAL receiver should create a temporary replication slot if no permanent slot is configured."),
+		},
+		&wal_receiver_create_temp_slot,
+		false,
+		NULL, NULL, NULL
+	},
+
+	/* End-of-list marker */
+	{
+		{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL
+	}
+};
+
+
+static struct config_int ConfigureNamesInt[] =
+{
+	{
+		{"archive_timeout", PGC_SIGHUP, WAL_ARCHIVING,
+			gettext_noop("Forces a switch to the next WAL file if a "
+						 "new file has not been started within N seconds."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&XLogArchiveTimeout,
+		0, 0, INT_MAX / 2,
+		NULL, NULL, NULL
+	},
+	{
+		{"post_auth_delay", PGC_BACKEND, DEVELOPER_OPTIONS,
+			gettext_noop("Waits N seconds on connection startup after authentication."),
+			gettext_noop("This allows attaching a debugger to the process."),
+			GUC_NOT_IN_SAMPLE | GUC_UNIT_S
+		},
+		&PostAuthDelay,
+		0, 0, INT_MAX / 1000000,
+		NULL, NULL, NULL
+	},
+	{
+		{"default_statistics_target", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Sets the default statistics target."),
+			gettext_noop("This applies to table columns that have not had a "
+						 "column-specific target set via ALTER TABLE SET STATISTICS.")
+		},
+		&default_statistics_target,
+		100, 1, 10000,
+		NULL, NULL, NULL
+	},
+	{
+		{"from_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Sets the FROM-list size beyond which subqueries "
+						 "are not collapsed."),
+			gettext_noop("The planner will merge subqueries into upper "
+						 "queries if the resulting FROM list would have no more than "
+						 "this many items."),
+			GUC_EXPLAIN
+		},
+		&from_collapse_limit,
+		8, 1, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"join_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Sets the FROM-list size beyond which JOIN "
+						 "constructs are not flattened."),
+			gettext_noop("The planner will flatten explicit JOIN "
+						 "constructs into lists of FROM items whenever a "
+						 "list of no more than this many items would result."),
+			GUC_EXPLAIN
+		},
+		&join_collapse_limit,
+		8, 1, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo_threshold", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("Sets the threshold of FROM items beyond which GEQO is used."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&geqo_threshold,
+		12, 2, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo_effort", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("GEQO: effort is used to set the default for other GEQO parameters."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&Geqo_effort,
+		DEFAULT_GEQO_EFFORT, MIN_GEQO_EFFORT, MAX_GEQO_EFFORT,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo_pool_size", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("GEQO: number of individuals in the population."),
+			gettext_noop("Zero selects a suitable default value."),
+			GUC_EXPLAIN
+		},
+		&Geqo_pool_size,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo_generations", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("GEQO: number of iterations of the algorithm."),
+			gettext_noop("Zero selects a suitable default value."),
+			GUC_EXPLAIN
+		},
+		&Geqo_generations,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		/* This is PGC_SUSET to prevent hiding from log_lock_waits. */
+		{"deadlock_timeout", PGC_SUSET, LOCK_MANAGEMENT,
+			gettext_noop("Sets the time to wait on a lock before checking for deadlock."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&DeadlockTimeout,
+		1000, 1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_standby_archive_delay", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the maximum delay before canceling queries when a hot standby server is processing archived WAL data."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&max_standby_archive_delay,
+		30 * 1000, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_standby_streaming_delay", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the maximum delay before canceling queries when a hot standby server is processing streamed WAL data."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&max_standby_streaming_delay,
+		30 * 1000, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_min_apply_delay", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the minimum delay for applying changes during recovery."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&recovery_min_apply_delay,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_receiver_status_interval", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the maximum interval between WAL receiver status reports to the sending server."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&wal_receiver_status_interval,
+		10, 0, INT_MAX / 1000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_receiver_timeout", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the maximum wait time to receive data from the sending server."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&wal_receiver_timeout,
+		60 * 1000, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_connections", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the maximum number of concurrent connections."),
+			NULL
+		},
+		&MaxConnections,
+		100, 1, MAX_BACKENDS,
+		check_maxconnections, NULL, NULL
+	},
+
+	{
+		/* see max_connections */
+		{"superuser_reserved_connections", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the number of connection slots reserved for superusers."),
+			NULL
+		},
+		&ReservedBackends,
+		3, 0, MAX_BACKENDS,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"min_dynamic_shared_memory", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Amount of dynamic shared memory reserved at startup."),
+			NULL,
+			GUC_UNIT_MB
+		},
+		&min_dynamic_shared_memory,
+		0, 0, (int) Min((size_t) INT_MAX, SIZE_MAX / (1024 * 1024)),
+		NULL, NULL, NULL
+	},
+
+	/*
+	 * We sometimes multiply the number of shared buffers by two without
+	 * checking for overflow, so we mustn't allow more than INT_MAX / 2.
+	 */
+	{
+		{"shared_buffers", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Sets the number of shared memory buffers used by the server."),
+			NULL,
+			GUC_UNIT_BLOCKS
+		},
+		&NBuffers,
+		1024, 16, INT_MAX / 2,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"temp_buffers", PGC_USERSET, RESOURCES_MEM,
+			gettext_noop("Sets the maximum number of temporary buffers used by each session."),
+			NULL,
+			GUC_UNIT_BLOCKS | GUC_EXPLAIN
+		},
+		&num_temp_buffers,
+		1024, 100, INT_MAX / 2,
+		check_temp_buffers, NULL, NULL
+	},
+
+	{
+		{"port", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the TCP port the server listens on."),
+			NULL
+		},
+		&PostPortNumber,
+		DEF_PGPORT, 1, 65535,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"unix_socket_permissions", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the access permissions of the Unix-domain socket."),
+			gettext_noop("Unix-domain sockets use the usual Unix file system "
+						 "permission set. The parameter value is expected "
+						 "to be a numeric mode specification in the form "
+						 "accepted by the chmod and umask system calls. "
+						 "(To use the customary octal format the number must "
+						 "start with a 0 (zero).)")
+		},
+		&Unix_socket_permissions,
+		0777, 0000, 0777,
+		NULL, NULL, show_unix_socket_permissions
+	},
+
+	{
+		{"log_file_mode", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the file permissions for log files."),
+			gettext_noop("The parameter value is expected "
+						 "to be a numeric mode specification in the form "
+						 "accepted by the chmod and umask system calls. "
+						 "(To use the customary octal format the number must "
+						 "start with a 0 (zero).)")
+		},
+		&Log_file_mode,
+		0600, 0000, 0777,
+		NULL, NULL, show_log_file_mode
+	},
+
+
+	{
+		{"data_directory_mode", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the mode of the data directory."),
+			gettext_noop("The parameter value is a numeric mode specification "
+						 "in the form accepted by the chmod and umask system "
+						 "calls. (To use the customary octal format the number "
+						 "must start with a 0 (zero).)"),
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&data_directory_mode,
+		0700, 0000, 0777,
+		NULL, NULL, show_data_directory_mode
+	},
+
+	{
+		{"work_mem", PGC_USERSET, RESOURCES_MEM,
+			gettext_noop("Sets the maximum memory to be used for query workspaces."),
+			gettext_noop("This much memory can be used by each internal "
+						 "sort operation and hash table before switching to "
+						 "temporary disk files."),
+			GUC_UNIT_KB | GUC_EXPLAIN
+		},
+		&work_mem,
+		4096, 64, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"maintenance_work_mem", PGC_USERSET, RESOURCES_MEM,
+			gettext_noop("Sets the maximum memory to be used for maintenance operations."),
+			gettext_noop("This includes operations such as VACUUM and CREATE INDEX."),
+			GUC_UNIT_KB
+		},
+		&maintenance_work_mem,
+		65536, 1024, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"logical_decoding_work_mem", PGC_USERSET, RESOURCES_MEM,
+			gettext_noop("Sets the maximum memory to be used for logical decoding."),
+			gettext_noop("This much memory can be used by each internal "
+						 "reorder buffer before spilling to disk."),
+			GUC_UNIT_KB
+		},
+		&logical_decoding_work_mem,
+		65536, 64, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	/*
+	 * We use the hopefully-safely-small value of 100kB as the compiled-in
+	 * default for max_stack_depth.  InitializeGUCOptions will increase it if
+	 * possible, depending on the actual platform-specific stack limit.
+	 */
+	{
+		{"max_stack_depth", PGC_SUSET, RESOURCES_MEM,
+			gettext_noop("Sets the maximum stack depth, in kilobytes."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&max_stack_depth,
+		100, 100, MAX_KILOBYTES,
+		check_max_stack_depth, assign_max_stack_depth, NULL
+	},
+
+	{
+		{"temp_file_limit", PGC_SUSET, RESOURCES_DISK,
+			gettext_noop("Limits the total size of all temporary files used by each process."),
+			gettext_noop("-1 means no limit."),
+			GUC_UNIT_KB
+		},
+		&temp_file_limit,
+		-1, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_cost_page_hit", PGC_USERSET, RESOURCES_VACUUM_DELAY,
+			gettext_noop("Vacuum cost for a page found in the buffer cache."),
+			NULL
+		},
+		&VacuumCostPageHit,
+		1, 0, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_cost_page_miss", PGC_USERSET, RESOURCES_VACUUM_DELAY,
+			gettext_noop("Vacuum cost for a page not found in the buffer cache."),
+			NULL
+		},
+		&VacuumCostPageMiss,
+		2, 0, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_cost_page_dirty", PGC_USERSET, RESOURCES_VACUUM_DELAY,
+			gettext_noop("Vacuum cost for a page dirtied by vacuum."),
+			NULL
+		},
+		&VacuumCostPageDirty,
+		20, 0, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_cost_limit", PGC_USERSET, RESOURCES_VACUUM_DELAY,
+			gettext_noop("Vacuum cost amount available before napping."),
+			NULL
+		},
+		&VacuumCostLimit,
+		200, 1, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_vacuum_cost_limit", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Vacuum cost amount available before napping, for autovacuum."),
+			NULL
+		},
+		&autovacuum_vac_cost_limit,
+		-1, -1, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_files_per_process", PGC_POSTMASTER, RESOURCES_KERNEL,
+			gettext_noop("Sets the maximum number of simultaneously open files for each server process."),
+			NULL
+		},
+		&max_files_per_process,
+		1000, 64, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	/*
+	 * See also CheckRequiredParameterValues() if this parameter changes
+	 */
+	{
+		{"max_prepared_transactions", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Sets the maximum number of simultaneously prepared transactions."),
+			NULL
+		},
+		&max_prepared_xacts,
+		0, 0, MAX_BACKENDS,
+		NULL, NULL, NULL
+	},
+
+#ifdef LOCK_DEBUG
+	{
+		{"trace_lock_oidmin", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Sets the minimum OID of tables for tracking locks."),
+			gettext_noop("Is used to avoid output on system tables."),
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_lock_oidmin,
+		FirstNormalObjectId, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"trace_lock_table", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Sets the OID of the table with unconditionally lock tracing."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&Trace_lock_table,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+#endif
+
+	{
+		{"statement_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum allowed duration of any statement."),
+			gettext_noop("A value of 0 turns off the timeout."),
+			GUC_UNIT_MS
+		},
+		&StatementTimeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"lock_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum allowed duration of any wait for a lock."),
+			gettext_noop("A value of 0 turns off the timeout."),
+			GUC_UNIT_MS
+		},
+		&LockTimeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"idle_in_transaction_session_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum allowed idle time between queries, when in a transaction."),
+			gettext_noop("A value of 0 turns off the timeout."),
+			GUC_UNIT_MS
+		},
+		&IdleInTransactionSessionTimeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"idle_session_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum allowed idle time between queries, when not in a transaction."),
+			gettext_noop("A value of 0 turns off the timeout."),
+			GUC_UNIT_MS
+		},
+		&IdleSessionTimeout,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_freeze_min_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Minimum age at which VACUUM should freeze a table row."),
+			NULL
+		},
+		&vacuum_freeze_min_age,
+		50000000, 0, 1000000000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_freeze_table_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Age at which VACUUM should scan whole table to freeze tuples."),
+			NULL
+		},
+		&vacuum_freeze_table_age,
+		150000000, 0, 2000000000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_multixact_freeze_min_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Minimum age at which VACUUM should freeze a MultiXactId in a table row."),
+			NULL
+		},
+		&vacuum_multixact_freeze_min_age,
+		5000000, 0, 1000000000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_multixact_freeze_table_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Multixact age at which VACUUM should scan whole table to freeze tuples."),
+			NULL
+		},
+		&vacuum_multixact_freeze_table_age,
+		150000000, 0, 2000000000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"vacuum_defer_cleanup_age", PGC_SIGHUP, REPLICATION_PRIMARY,
+			gettext_noop("Number of transactions by which VACUUM and HOT cleanup should be deferred, if any."),
+			NULL
+		},
+		&vacuum_defer_cleanup_age,
+		0, 0, 1000000,			/* see ComputeXidHorizons */
+		NULL, NULL, NULL
+	},
+	{
+		{"vacuum_failsafe_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Age at which VACUUM should trigger failsafe to avoid a wraparound outage."),
+			NULL
+		},
+		&vacuum_failsafe_age,
+		1600000000, 0, 2100000000,
+		NULL, NULL, NULL
+	},
+	{
+		{"vacuum_multixact_failsafe_age", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Multixact age at which VACUUM should trigger failsafe to avoid a wraparound outage."),
+			NULL
+		},
+		&vacuum_multixact_failsafe_age,
+		1600000000, 0, 2100000000,
+		NULL, NULL, NULL
+	},
+
+	/*
+	 * See also CheckRequiredParameterValues() if this parameter changes
+	 */
+	{
+		{"max_locks_per_transaction", PGC_POSTMASTER, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of locks per transaction."),
+			gettext_noop("The shared lock table is sized on the assumption that "
+						 "at most max_locks_per_transaction * max_connections distinct "
+						 "objects will need to be locked at any one time.")
+		},
+		&max_locks_per_xact,
+		64, 10, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_pred_locks_per_transaction", PGC_POSTMASTER, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of predicate locks per transaction."),
+			gettext_noop("The shared predicate lock table is sized on the assumption that "
+						 "at most max_pred_locks_per_transaction * max_connections distinct "
+						 "objects will need to be locked at any one time.")
+		},
+		&max_predicate_locks_per_xact,
+		64, 10, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_pred_locks_per_relation", PGC_SIGHUP, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of predicate-locked pages and tuples per relation."),
+			gettext_noop("If more than this total of pages and tuples in the same relation are locked "
+						 "by a connection, those locks are replaced by a relation-level lock.")
+		},
+		&max_predicate_locks_per_relation,
+		-2, INT_MIN, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_pred_locks_per_page", PGC_SIGHUP, LOCK_MANAGEMENT,
+			gettext_noop("Sets the maximum number of predicate-locked tuples per page."),
+			gettext_noop("If more than this number of tuples on the same page are locked "
+						 "by a connection, those locks are replaced by a page-level lock.")
+		},
+		&max_predicate_locks_per_page,
+		2, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"authentication_timeout", PGC_SIGHUP, CONN_AUTH_AUTH,
+			gettext_noop("Sets the maximum allowed time to complete client authentication."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&AuthenticationTimeout,
+		60, 1, 600,
+		NULL, NULL, NULL
+	},
+
+	{
+		/* Not for general use */
+		{"pre_auth_delay", PGC_SIGHUP, DEVELOPER_OPTIONS,
+			gettext_noop("Waits N seconds on connection startup before authentication."),
+			gettext_noop("This allows attaching a debugger to the process."),
+			GUC_NOT_IN_SAMPLE | GUC_UNIT_S
+		},
+		&PreAuthDelay,
+		0, 0, 60,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_keep_size", PGC_SIGHUP, REPLICATION_SENDING,
+			gettext_noop("Sets the size of WAL files held for standby servers."),
+			NULL,
+			GUC_UNIT_MB
+		},
+		&wal_keep_size_mb,
+		0, 0, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"min_wal_size", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Sets the minimum size to shrink the WAL to."),
+			NULL,
+			GUC_UNIT_MB
+		},
+		&min_wal_size_mb,
+		DEFAULT_MIN_WAL_SEGS * (DEFAULT_XLOG_SEG_SIZE / (1024 * 1024)),
+		2, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_wal_size", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Sets the WAL size that triggers a checkpoint."),
+			NULL,
+			GUC_UNIT_MB
+		},
+		&max_wal_size_mb,
+		DEFAULT_MAX_WAL_SEGS * (DEFAULT_XLOG_SEG_SIZE / (1024 * 1024)),
+		2, MAX_KILOBYTES,
+		NULL, assign_max_wal_size, NULL
+	},
+
+	{
+		{"checkpoint_timeout", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Sets the maximum time between automatic WAL checkpoints."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&CheckPointTimeout,
+		300, 30, 86400,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"checkpoint_warning", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Enables warnings if checkpoint segments are filled more "
+						 "frequently than this."),
+			gettext_noop("Write a message to the server log if checkpoints "
+						 "caused by the filling of checkpoint segment files happens more "
+						 "frequently than this number of seconds. Zero turns off the warning."),
+			GUC_UNIT_S
+		},
+		&CheckPointWarning,
+		30, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"checkpoint_flush_after", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
+			NULL,
+			GUC_UNIT_BLOCKS
+		},
+		&checkpoint_flush_after,
+		DEFAULT_CHECKPOINT_FLUSH_AFTER, 0, WRITEBACK_MAX_PENDING_FLUSHES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_buffers", PGC_POSTMASTER, WAL_SETTINGS,
+			gettext_noop("Sets the number of disk-page buffers in shared memory for WAL."),
+			NULL,
+			GUC_UNIT_XBLOCKS
+		},
+		&XLOGbuffers,
+		-1, -1, (INT_MAX / XLOG_BLCKSZ),
+		check_wal_buffers, NULL, NULL
+	},
+
+	{
+		{"wal_writer_delay", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Time between WAL flushes performed in the WAL writer."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&WalWriterDelay,
+		200, 1, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_writer_flush_after", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Amount of WAL written out by WAL writer that triggers a flush."),
+			NULL,
+			GUC_UNIT_XBLOCKS
+		},
+		&WalWriterFlushAfter,
+		(1024 * 1024) / XLOG_BLCKSZ, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_skip_threshold", PGC_USERSET, WAL_SETTINGS,
+			gettext_noop("Minimum size of new file to fsync instead of writing WAL."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&wal_skip_threshold,
+		2048, 0, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_wal_senders", PGC_POSTMASTER, REPLICATION_SENDING,
+			gettext_noop("Sets the maximum number of simultaneously running WAL sender processes."),
+			NULL
+		},
+		&max_wal_senders,
+		10, 0, MAX_BACKENDS,
+		check_max_wal_senders, NULL, NULL
+	},
+
+	{
+		/* see max_wal_senders */
+		{"max_replication_slots", PGC_POSTMASTER, REPLICATION_SENDING,
+			gettext_noop("Sets the maximum number of simultaneously defined replication slots."),
+			NULL
+		},
+		&max_replication_slots,
+		10, 0, MAX_BACKENDS /* XXX? */ ,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_slot_wal_keep_size", PGC_SIGHUP, REPLICATION_SENDING,
+			gettext_noop("Sets the maximum WAL size that can be reserved by replication slots."),
+			gettext_noop("Replication slots will be marked as failed, and segments released "
+						 "for deletion or recycling, if this much space is occupied by WAL "
+						 "on disk."),
+			GUC_UNIT_MB
+		},
+		&max_slot_wal_keep_size_mb,
+		-1, -1, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_sender_timeout", PGC_USERSET, REPLICATION_SENDING,
+			gettext_noop("Sets the maximum time to wait for WAL replication."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&wal_sender_timeout,
+		60 * 1000, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"commit_delay", PGC_SUSET, WAL_SETTINGS,
+			gettext_noop("Sets the delay in microseconds between transaction commit and "
+						 "flushing WAL to disk."),
+			NULL
+			/* we have no microseconds designation, so can't supply units here */
+		},
+		&CommitDelay,
+		0, 0, 100000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"commit_siblings", PGC_USERSET, WAL_SETTINGS,
+			gettext_noop("Sets the minimum concurrent open transactions before performing "
+						 "commit_delay."),
+			NULL
+		},
+		&CommitSiblings,
+		5, 0, 1000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"extra_float_digits", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the number of digits displayed for floating-point values."),
+			gettext_noop("This affects real, double precision, and geometric data types. "
+						 "A zero or negative parameter value is added to the standard "
+						 "number of digits (FLT_DIG or DBL_DIG as appropriate). "
+						 "Any value greater than zero selects precise output mode.")
+		},
+		&extra_float_digits,
+		1, -15, 3,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_min_duration_sample", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Sets the minimum execution time above which "
+						 "a sample of statements will be logged."
+						 " Sampling is determined by log_statement_sample_rate."),
+			gettext_noop("Zero logs a sample of all queries. -1 turns this feature off."),
+			GUC_UNIT_MS
+		},
+		&log_min_duration_sample,
+		-1, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_min_duration_statement", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Sets the minimum execution time above which "
+						 "all statements will be logged."),
+			gettext_noop("Zero prints all queries. -1 turns this feature off."),
+			GUC_UNIT_MS
+		},
+		&log_min_duration_statement,
+		-1, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_autovacuum_min_duration", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Sets the minimum execution time above which "
+						 "autovacuum actions will be logged."),
+			gettext_noop("Zero prints all actions. -1 turns autovacuum logging off."),
+			GUC_UNIT_MS
+		},
+		&Log_autovacuum_min_duration,
+		-1, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_parameter_max_length", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("When logging statements, limit logged parameter values to first N bytes."),
+			gettext_noop("-1 to print values in full."),
+			GUC_UNIT_BYTE
+		},
+		&log_parameter_max_length,
+		-1, -1, INT_MAX / 2,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_parameter_max_length_on_error", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("When reporting an error, limit logged parameter values to first N bytes."),
+			gettext_noop("-1 to print values in full."),
+			GUC_UNIT_BYTE
+		},
+		&log_parameter_max_length_on_error,
+		0, -1, INT_MAX / 2,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bgwriter_delay", PGC_SIGHUP, RESOURCES_BGWRITER,
+			gettext_noop("Background writer sleep time between rounds."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&BgWriterDelay,
+		200, 10, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bgwriter_lru_maxpages", PGC_SIGHUP, RESOURCES_BGWRITER,
+			gettext_noop("Background writer maximum number of LRU pages to flush per round."),
+			NULL
+		},
+		&bgwriter_lru_maxpages,
+		100, 0, INT_MAX / 2,	/* Same upper limit as shared_buffers */
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bgwriter_flush_after", PGC_SIGHUP, RESOURCES_BGWRITER,
+			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
+			NULL,
+			GUC_UNIT_BLOCKS
+		},
+		&bgwriter_flush_after,
+		DEFAULT_BGWRITER_FLUSH_AFTER, 0, WRITEBACK_MAX_PENDING_FLUSHES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"effective_io_concurrency",
+			PGC_USERSET,
+			RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Number of simultaneous requests that can be handled efficiently by the disk subsystem."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&effective_io_concurrency,
+#ifdef USE_PREFETCH
+		1,
+#else
+		0,
+#endif
+		0, MAX_IO_CONCURRENCY,
+		check_effective_io_concurrency, NULL, NULL
+	},
+
+	{
+		{"maintenance_io_concurrency",
+			PGC_USERSET,
+			RESOURCES_ASYNCHRONOUS,
+			gettext_noop("A variant of effective_io_concurrency that is used for maintenance work."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&maintenance_io_concurrency,
+#ifdef USE_PREFETCH
+		10,
+#else
+		0,
+#endif
+		0, MAX_IO_CONCURRENCY,
+		check_maintenance_io_concurrency, NULL, NULL
+	},
+
+	{
+		{"backend_flush_after", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
+			NULL,
+			GUC_UNIT_BLOCKS
+		},
+		&backend_flush_after,
+		DEFAULT_BACKEND_FLUSH_AFTER, 0, WRITEBACK_MAX_PENDING_FLUSHES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_worker_processes",
+			PGC_POSTMASTER,
+			RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Maximum number of concurrent worker processes."),
+			NULL,
+		},
+		&max_worker_processes,
+		8, 0, MAX_BACKENDS,
+		check_max_worker_processes, NULL, NULL
+	},
+
+	{
+		{"max_logical_replication_workers",
+			PGC_POSTMASTER,
+			REPLICATION_SUBSCRIBERS,
+			gettext_noop("Maximum number of logical replication worker processes."),
+			NULL,
+		},
+		&max_logical_replication_workers,
+		4, 0, MAX_BACKENDS,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_sync_workers_per_subscription",
+			PGC_SIGHUP,
+			REPLICATION_SUBSCRIBERS,
+			gettext_noop("Maximum number of table synchronization workers per subscription."),
+			NULL,
+		},
+		&max_sync_workers_per_subscription,
+		2, 0, MAX_BACKENDS,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_rotation_age", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Automatic log file rotation will occur after N minutes."),
+			NULL,
+			GUC_UNIT_MIN
+		},
+		&Log_RotationAge,
+		HOURS_PER_DAY * MINS_PER_HOUR, 0, INT_MAX / SECS_PER_MINUTE,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_rotation_size", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Automatic log file rotation will occur after N kilobytes."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&Log_RotationSize,
+		10 * 1024, 0, INT_MAX / 1024,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_function_args", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the maximum number of function arguments."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&max_function_args,
+		FUNC_MAX_ARGS, FUNC_MAX_ARGS, FUNC_MAX_ARGS,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_index_keys", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the maximum number of index keys."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&max_index_keys,
+		INDEX_MAX_KEYS, INDEX_MAX_KEYS, INDEX_MAX_KEYS,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_identifier_length", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the maximum identifier length."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&max_identifier_length,
+		NAMEDATALEN - 1, NAMEDATALEN - 1, NAMEDATALEN - 1,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"block_size", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the size of a disk block."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&block_size,
+		BLCKSZ, BLCKSZ, BLCKSZ,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"segment_size", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the number of pages per disk file."),
+			NULL,
+			GUC_UNIT_BLOCKS | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&segment_size,
+		RELSEG_SIZE, RELSEG_SIZE, RELSEG_SIZE,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_block_size", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the block size in the write ahead log."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&wal_block_size,
+		XLOG_BLCKSZ, XLOG_BLCKSZ, XLOG_BLCKSZ,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_retrieve_retry_interval", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the time to wait before retrying to retrieve WAL "
+						 "after a failed attempt."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&wal_retrieve_retry_interval,
+		5000, 1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_segment_size", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the size of write ahead log segments."),
+			NULL,
+			GUC_UNIT_BYTE | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&wal_segment_size,
+		DEFAULT_XLOG_SEG_SIZE,
+		WalSegMinSize,
+		WalSegMaxSize,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_naptime", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Time to sleep between autovacuum runs."),
+			NULL,
+			GUC_UNIT_S
+		},
+		&autovacuum_naptime,
+		60, 1, INT_MAX / 1000,
+		NULL, NULL, NULL
+	},
+	{
+		{"autovacuum_vacuum_threshold", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Minimum number of tuple updates or deletes prior to vacuum."),
+			NULL
+		},
+		&autovacuum_vac_thresh,
+		50, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"autovacuum_vacuum_insert_threshold", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Minimum number of tuple inserts prior to vacuum, or -1 to disable insert vacuums."),
+			NULL
+		},
+		&autovacuum_vac_ins_thresh,
+		1000, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"autovacuum_analyze_threshold", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Minimum number of tuple inserts, updates, or deletes prior to analyze."),
+			NULL
+		},
+		&autovacuum_anl_thresh,
+		50, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		/* see varsup.c for why this is PGC_POSTMASTER not PGC_SIGHUP */
+		{"autovacuum_freeze_max_age", PGC_POSTMASTER, AUTOVACUUM,
+			gettext_noop("Age at which to autovacuum a table to prevent transaction ID wraparound."),
+			NULL
+		},
+		&autovacuum_freeze_max_age,
+
+		/*
+		 * see pg_resetwal and vacuum_failsafe_age if you change the
+		 * upper-limit value.
+		 */
+		200000000, 100000, 2000000000,
+		NULL, NULL, NULL
+	},
+	{
+		/* see multixact.c for why this is PGC_POSTMASTER not PGC_SIGHUP */
+		{"autovacuum_multixact_freeze_max_age", PGC_POSTMASTER, AUTOVACUUM,
+			gettext_noop("Multixact age at which to autovacuum a table to prevent multixact wraparound."),
+			NULL
+		},
+		&autovacuum_multixact_freeze_max_age,
+		400000000, 10000, 2000000000,
+		NULL, NULL, NULL
+	},
+	{
+		/* see max_connections */
+		{"autovacuum_max_workers", PGC_POSTMASTER, AUTOVACUUM,
+			gettext_noop("Sets the maximum number of simultaneously running autovacuum worker processes."),
+			NULL
+		},
+		&autovacuum_max_workers,
+		3, 1, MAX_BACKENDS,
+		check_autovacuum_max_workers, NULL, NULL
+	},
+
+	{
+		{"max_parallel_maintenance_workers", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Sets the maximum number of parallel processes per maintenance operation."),
+			NULL
+		},
+		&max_parallel_maintenance_workers,
+		2, 0, 1024,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_parallel_workers_per_gather", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Sets the maximum number of parallel processes per executor node."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&max_parallel_workers_per_gather,
+		2, 0, MAX_PARALLEL_WORKER_LIMIT,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"max_parallel_workers", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Sets the maximum number of parallel workers that can be active at one time."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&max_parallel_workers,
+		8, 0, MAX_PARALLEL_WORKER_LIMIT,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_work_mem", PGC_SIGHUP, RESOURCES_MEM,
+			gettext_noop("Sets the maximum memory to be used by each autovacuum worker process."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&autovacuum_work_mem,
+		-1, -1, MAX_KILOBYTES,
+		check_autovacuum_work_mem, NULL, NULL
+	},
+
+	{
+		{"old_snapshot_threshold", PGC_POSTMASTER, RESOURCES_ASYNCHRONOUS,
+			gettext_noop("Time before a snapshot is too old to read pages changed after the snapshot was taken."),
+			gettext_noop("A value of -1 disables this feature."),
+			GUC_UNIT_MIN
+		},
+		&old_snapshot_threshold,
+		-1, -1, MINS_PER_HOUR * HOURS_PER_DAY * 60,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"tcp_keepalives_idle", PGC_USERSET, CONN_AUTH_SETTINGS,
+			gettext_noop("Time between issuing TCP keepalives."),
+			gettext_noop("A value of 0 uses the system default."),
+			GUC_UNIT_S
+		},
+		&tcp_keepalives_idle,
+		0, 0, INT_MAX,
+		NULL, assign_tcp_keepalives_idle, show_tcp_keepalives_idle
+	},
+
+	{
+		{"tcp_keepalives_interval", PGC_USERSET, CONN_AUTH_SETTINGS,
+			gettext_noop("Time between TCP keepalive retransmits."),
+			gettext_noop("A value of 0 uses the system default."),
+			GUC_UNIT_S
+		},
+		&tcp_keepalives_interval,
+		0, 0, INT_MAX,
+		NULL, assign_tcp_keepalives_interval, show_tcp_keepalives_interval
+	},
+
+	{
+		{"ssl_renegotiation_limit", PGC_USERSET, CONN_AUTH_SSL,
+			gettext_noop("SSL renegotiation is no longer supported; this can only be 0."),
+			NULL,
+			GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE,
+		},
+		&ssl_renegotiation_limit,
+		0, 0, 0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"tcp_keepalives_count", PGC_USERSET, CONN_AUTH_SETTINGS,
+			gettext_noop("Maximum number of TCP keepalive retransmits."),
+			gettext_noop("This controls the number of consecutive keepalive retransmits that can be "
+						 "lost before a connection is considered dead. A value of 0 uses the "
+						 "system default."),
+		},
+		&tcp_keepalives_count,
+		0, 0, INT_MAX,
+		NULL, assign_tcp_keepalives_count, show_tcp_keepalives_count
+	},
+
+	{
+		{"gin_fuzzy_search_limit", PGC_USERSET, CLIENT_CONN_OTHER,
+			gettext_noop("Sets the maximum allowed result for exact search by GIN."),
+			NULL,
+			0
+		},
+		&GinFuzzySearchLimit,
+		0, 0, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"effective_cache_size", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's assumption about the total size of the data caches."),
+			gettext_noop("That is, the total size of the caches (kernel cache and shared buffers) used for PostgreSQL data files. "
+						 "This is measured in disk pages, which are normally 8 kB each."),
+			GUC_UNIT_BLOCKS | GUC_EXPLAIN,
+		},
+		&effective_cache_size,
+		DEFAULT_EFFECTIVE_CACHE_SIZE, 1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"min_parallel_table_scan_size", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the minimum amount of table data for a parallel scan."),
+			gettext_noop("If the planner estimates that it will read a number of table pages too small to reach this limit, a parallel scan will not be considered."),
+			GUC_UNIT_BLOCKS | GUC_EXPLAIN,
+		},
+		&min_parallel_table_scan_size,
+		(8 * 1024 * 1024) / BLCKSZ, 0, INT_MAX / 3,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"min_parallel_index_scan_size", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the minimum amount of index data for a parallel scan."),
+			gettext_noop("If the planner estimates that it will read a number of index pages too small to reach this limit, a parallel scan will not be considered."),
+			GUC_UNIT_BLOCKS | GUC_EXPLAIN,
+		},
+		&min_parallel_index_scan_size,
+		(512 * 1024) / BLCKSZ, 0, INT_MAX / 3,
+		NULL, NULL, NULL
+	},
+
+	{
+		/* Can't be set in postgresql.conf */
+		{"server_version_num", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the server version as an integer."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&server_version_num,
+		PG_VERSION_NUM, PG_VERSION_NUM, PG_VERSION_NUM,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_temp_files", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Log the use of temporary files larger than this number of kilobytes."),
+			gettext_noop("Zero logs all files. The default is -1 (turning this feature off)."),
+			GUC_UNIT_KB
+		},
+		&log_temp_files,
+		-1, -1, INT_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"track_activity_query_size", PGC_POSTMASTER, STATS_COLLECTOR,
+			gettext_noop("Sets the size reserved for pg_stat_activity.query, in bytes."),
+			NULL,
+			GUC_UNIT_BYTE
+		},
+		&pgstat_track_activity_query_size,
+		1024, 100, 1048576,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"gin_pending_list_limit", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the maximum size of the pending list for GIN index."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&gin_pending_list_limit,
+		4096, 64, MAX_KILOBYTES,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"tcp_user_timeout", PGC_USERSET, CONN_AUTH_SETTINGS,
+			gettext_noop("TCP user timeout."),
+			gettext_noop("A value of 0 uses the system default."),
+			GUC_UNIT_MS
+		},
+		&tcp_user_timeout,
+		0, 0, INT_MAX,
+		NULL, assign_tcp_user_timeout, show_tcp_user_timeout
+	},
+
+	{
+		{"huge_page_size", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("The size of huge page that should be requested."),
+			NULL,
+			GUC_UNIT_KB
+		},
+		&huge_page_size,
+		0, 0, INT_MAX,
+		check_huge_page_size, NULL, NULL
+	},
+
+	{
+		{"debug_discard_caches", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Aggressively flush system caches for debugging purposes."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&debug_discard_caches,
+#ifdef DISCARD_CACHES_ENABLED
+		/* Set default based on older compile-time-only cache clobber macros */
+#if defined(CLOBBER_CACHE_RECURSIVELY)
+		3,
+#elif defined(CLOBBER_CACHE_ALWAYS)
+		1,
+#else
+		0,
+#endif
+		0, 5,
+#else							/* not DISCARD_CACHES_ENABLED */
+		0, 0, 0,
+#endif							/* not DISCARD_CACHES_ENABLED */
+		NULL, NULL, NULL
+	},
+
+	{
+		{"client_connection_check_interval", PGC_USERSET, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the time interval between checks for disconnection while running queries."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&client_connection_check_interval,
+		0, 0, INT_MAX,
+		check_client_connection_check_interval, NULL, NULL
+	},
+
+	/* End-of-list marker */
+	{
+		{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL
+	}
+};
+
+
+static struct config_real ConfigureNamesReal[] =
+{
+	{
+		{"seq_page_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of a "
+						 "sequentially fetched disk page."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&seq_page_cost,
+		DEFAULT_SEQ_PAGE_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"random_page_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of a "
+						 "nonsequentially fetched disk page."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&random_page_cost,
+		DEFAULT_RANDOM_PAGE_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"cpu_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of "
+						 "processing each tuple (row)."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&cpu_tuple_cost,
+		DEFAULT_CPU_TUPLE_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"cpu_index_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of "
+						 "processing each index entry during an index scan."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&cpu_index_tuple_cost,
+		DEFAULT_CPU_INDEX_TUPLE_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"cpu_operator_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of "
+						 "processing each operator or function call."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&cpu_operator_cost,
+		DEFAULT_CPU_OPERATOR_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"parallel_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of "
+						 "passing each tuple (row) from worker to leader backend."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&parallel_tuple_cost,
+		DEFAULT_PARALLEL_TUPLE_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+	{
+		{"parallel_setup_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Sets the planner's estimate of the cost of "
+						 "starting up worker processes for parallel query."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&parallel_setup_cost,
+		DEFAULT_PARALLEL_SETUP_COST, 0, DBL_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_above_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Perform JIT compilation if query is more expensive."),
+			gettext_noop("-1 disables JIT compilation."),
+			GUC_EXPLAIN
+		},
+		&jit_above_cost,
+		100000, -1, DBL_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_optimize_above_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Optimize JIT-compiled functions if query is more expensive."),
+			gettext_noop("-1 disables optimization."),
+			GUC_EXPLAIN
+		},
+		&jit_optimize_above_cost,
+		500000, -1, DBL_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"jit_inline_above_cost", PGC_USERSET, QUERY_TUNING_COST,
+			gettext_noop("Perform JIT inlining if query is more expensive."),
+			gettext_noop("-1 disables inlining."),
+			GUC_EXPLAIN
+		},
+		&jit_inline_above_cost,
+		500000, -1, DBL_MAX,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"cursor_tuple_fraction", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Sets the planner's estimate of the fraction of "
+						 "a cursor's rows that will be retrieved."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&cursor_tuple_fraction,
+		DEFAULT_CURSOR_TUPLE_FRACTION, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"geqo_selection_bias", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("GEQO: selective pressure within the population."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&Geqo_selection_bias,
+		DEFAULT_GEQO_SELECTION_BIAS,
+		MIN_GEQO_SELECTION_BIAS, MAX_GEQO_SELECTION_BIAS,
+		NULL, NULL, NULL
+	},
+	{
+		{"geqo_seed", PGC_USERSET, QUERY_TUNING_GEQO,
+			gettext_noop("GEQO: seed for random path selection."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&Geqo_seed,
+		0.0, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"hash_mem_multiplier", PGC_USERSET, RESOURCES_MEM,
+			gettext_noop("Multiple of work_mem to use for hash tables."),
+			NULL,
+			GUC_EXPLAIN
+		},
+		&hash_mem_multiplier,
+		1.0, 1.0, 1000.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bgwriter_lru_multiplier", PGC_SIGHUP, RESOURCES_BGWRITER,
+			gettext_noop("Multiple of the average buffer usage to free per round."),
+			NULL
+		},
+		&bgwriter_lru_multiplier,
+		2.0, 0.0, 10.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"seed", PGC_USERSET, UNGROUPED,
+			gettext_noop("Sets the seed for random-number generation."),
+			NULL,
+			GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&phony_random_seed,
+		0.0, -1.0, 1.0,
+		check_random_seed, assign_random_seed, show_random_seed
+	},
+
+	{
+		{"vacuum_cost_delay", PGC_USERSET, RESOURCES_VACUUM_DELAY,
+			gettext_noop("Vacuum cost delay in milliseconds."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&VacuumCostDelay,
+		0, 0, 100,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_vacuum_cost_delay", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Vacuum cost delay in milliseconds, for autovacuum."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&autovacuum_vac_cost_delay,
+		2, -1, 100,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_vacuum_scale_factor", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Number of tuple updates or deletes prior to vacuum as a fraction of reltuples."),
+			NULL
+		},
+		&autovacuum_vac_scale,
+		0.2, 0.0, 100.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_vacuum_insert_scale_factor", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Number of tuple inserts prior to vacuum as a fraction of reltuples."),
+			NULL
+		},
+		&autovacuum_vac_ins_scale,
+		0.2, 0.0, 100.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"autovacuum_analyze_scale_factor", PGC_SIGHUP, AUTOVACUUM,
+			gettext_noop("Number of tuple inserts, updates, or deletes prior to analyze as a fraction of reltuples."),
+			NULL
+		},
+		&autovacuum_anl_scale,
+		0.1, 0.0, 100.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"checkpoint_completion_target", PGC_SIGHUP, WAL_CHECKPOINTS,
+			gettext_noop("Time spent flushing dirty buffers during checkpoint, as fraction of checkpoint interval."),
+			NULL
+		},
+		&CheckPointCompletionTarget,
+		0.9, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_statement_sample_rate", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Fraction of statements exceeding log_min_duration_sample to be logged."),
+			gettext_noop("Use a value between 0.0 (never log) and 1.0 (always log).")
+		},
+		&log_statement_sample_rate,
+		1.0, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_transaction_sample_rate", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Sets the fraction of transactions from which to log all statements."),
+			gettext_noop("Use a value between 0.0 (never log) and 1.0 (log all "
+						 "statements for all transactions).")
+		},
+		&log_xact_sample_rate,
+		0.0, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	/* End-of-list marker */
+	{
+		{NULL, 0, 0, NULL, NULL}, NULL, 0.0, 0.0, 0.0, NULL, NULL, NULL
+	}
+};
+
+
+static struct config_string ConfigureNamesString[] =
+{
+	{
+		{"archive_command", PGC_SIGHUP, WAL_ARCHIVING,
+			gettext_noop("Sets the shell command that will be called to archive a WAL file."),
+			NULL
+		},
+		&XLogArchiveCommand,
+		"",
+		NULL, NULL, show_archive_command
+	},
+
+	{
+		{"restore_command", PGC_SIGHUP, WAL_ARCHIVE_RECOVERY,
+			gettext_noop("Sets the shell command that will be called to retrieve an archived WAL file."),
+			NULL
+		},
+		&recoveryRestoreCommand,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"archive_cleanup_command", PGC_SIGHUP, WAL_ARCHIVE_RECOVERY,
+			gettext_noop("Sets the shell command that will be executed at every restart point."),
+			NULL
+		},
+		&archiveCleanupCommand,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_end_command", PGC_SIGHUP, WAL_ARCHIVE_RECOVERY,
+			gettext_noop("Sets the shell command that will be executed once at the end of recovery."),
+			NULL
+		},
+		&recoveryEndCommand,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_target_timeline", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Specifies the timeline to recover into."),
+			NULL
+		},
+		&recovery_target_timeline_string,
+		"latest",
+		check_recovery_target_timeline, assign_recovery_target_timeline, NULL
+	},
+
+	{
+		{"recovery_target", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Set to \"immediate\" to end recovery as soon as a consistent state is reached."),
+			NULL
+		},
+		&recovery_target_string,
+		"",
+		check_recovery_target, assign_recovery_target, NULL
+	},
+	{
+		{"recovery_target_xid", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets the transaction ID up to which recovery will proceed."),
+			NULL
+		},
+		&recovery_target_xid_string,
+		"",
+		check_recovery_target_xid, assign_recovery_target_xid, NULL
+	},
+	{
+		{"recovery_target_time", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets the time stamp up to which recovery will proceed."),
+			NULL
+		},
+		&recovery_target_time_string,
+		"",
+		check_recovery_target_time, assign_recovery_target_time, NULL
+	},
+	{
+		{"recovery_target_name", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets the named restore point up to which recovery will proceed."),
+			NULL
+		},
+		&recovery_target_name_string,
+		"",
+		check_recovery_target_name, assign_recovery_target_name, NULL
+	},
+	{
+		{"recovery_target_lsn", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets the LSN of the write-ahead log location up to which recovery will proceed."),
+			NULL
+		},
+		&recovery_target_lsn_string,
+		"",
+		check_recovery_target_lsn, assign_recovery_target_lsn, NULL
+	},
+
+	{
+		{"promote_trigger_file", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Specifies a file name whose presence ends recovery in the standby."),
+			NULL
+		},
+		&PromoteTriggerFile,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"primary_conninfo", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the connection string to be used to connect to the sending server."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&PrimaryConnInfo,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"primary_slot_name", PGC_SIGHUP, REPLICATION_STANDBY,
+			gettext_noop("Sets the name of the replication slot to use on the sending server."),
+			NULL
+		},
+		&PrimarySlotName,
+		"",
+		check_primary_slot_name, NULL, NULL
+	},
+
+	{
+		{"client_encoding", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the client's character set encoding."),
+			NULL,
+			GUC_IS_NAME | GUC_REPORT
+		},
+		&client_encoding_string,
+		"SQL_ASCII",
+		check_client_encoding, assign_client_encoding, NULL
+	},
+
+	{
+		{"log_line_prefix", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Controls information prefixed to each log line."),
+			gettext_noop("If blank, no prefix is used.")
+		},
+		&Log_line_prefix,
+		"%m [%p] ",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_timezone", PGC_SIGHUP, LOGGING_WHAT,
+			gettext_noop("Sets the time zone to use in log messages."),
+			NULL
+		},
+		&log_timezone_string,
+		"GMT",
+		check_log_timezone, assign_log_timezone, show_log_timezone
+	},
+
+	{
+		{"DateStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the display format for date and time values."),
+			gettext_noop("Also controls interpretation of ambiguous "
+						 "date inputs."),
+			GUC_LIST_INPUT | GUC_REPORT
+		},
+		&datestyle_string,
+		"ISO, MDY",
+		check_datestyle, assign_datestyle, NULL
+	},
+
+	{
+		{"default_table_access_method", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the default table access method for new tables."),
+			NULL,
+			GUC_IS_NAME
+		},
+		&default_table_access_method,
+		DEFAULT_TABLE_ACCESS_METHOD,
+		check_default_table_access_method, NULL, NULL
+	},
+
+	{
+		{"default_tablespace", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the default tablespace to create tables and indexes in."),
+			gettext_noop("An empty string selects the database's default tablespace."),
+			GUC_IS_NAME
+		},
+		&default_tablespace,
+		"",
+		check_default_tablespace, NULL, NULL
+	},
+
+	{
+		{"temp_tablespaces", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the tablespace(s) to use for temporary tables and sort files."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE
+		},
+		&temp_tablespaces,
+		"",
+		check_temp_tablespaces, assign_temp_tablespaces, NULL
+	},
+
+	{
+		{"dynamic_library_path", PGC_SUSET, CLIENT_CONN_OTHER,
+			gettext_noop("Sets the path for dynamically loadable modules."),
+			gettext_noop("If a dynamically loadable module needs to be opened and "
+						 "the specified name does not have a directory component (i.e., the "
+						 "name does not contain a slash), the system will search this path for "
+						 "the specified file."),
+			GUC_SUPERUSER_ONLY
+		},
+		&Dynamic_library_path,
+		"$libdir",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"krb_server_keyfile", PGC_SIGHUP, CONN_AUTH_AUTH,
+			gettext_noop("Sets the location of the Kerberos server key file."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&pg_krb_server_keyfile,
+		PG_KRB_SRVTAB,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bonjour_name", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the Bonjour service name."),
+			NULL
+		},
+		&bonjour_name,
+		"",
+		NULL, NULL, NULL
+	},
+
+	/* See main.c about why defaults for LC_foo are not all alike */
+
+	{
+		{"lc_collate", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the collation order locale."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&locale_collate,
+		"C",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"lc_ctype", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the character classification and case conversion locale."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&locale_ctype,
+		"C",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"lc_messages", PGC_SUSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the language in which messages are displayed."),
+			NULL
+		},
+		&locale_messages,
+		"",
+		check_locale_messages, assign_locale_messages, NULL
+	},
+
+	{
+		{"lc_monetary", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the locale for formatting monetary amounts."),
+			NULL
+		},
+		&locale_monetary,
+		"C",
+		check_locale_monetary, assign_locale_monetary, NULL
+	},
+
+	{
+		{"lc_numeric", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the locale for formatting numbers."),
+			NULL
+		},
+		&locale_numeric,
+		"C",
+		check_locale_numeric, assign_locale_numeric, NULL
+	},
+
+	{
+		{"lc_time", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the locale for formatting date and time values."),
+			NULL
+		},
+		&locale_time,
+		"C",
+		check_locale_time, assign_locale_time, NULL
+	},
+
+	{
+		{"session_preload_libraries", PGC_SUSET, CLIENT_CONN_PRELOAD,
+			gettext_noop("Lists shared libraries to preload into each backend."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_SUPERUSER_ONLY
+		},
+		&session_preload_libraries_string,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"shared_preload_libraries", PGC_POSTMASTER, CLIENT_CONN_PRELOAD,
+			gettext_noop("Lists shared libraries to preload into server."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_SUPERUSER_ONLY
+		},
+		&shared_preload_libraries_string,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"local_preload_libraries", PGC_USERSET, CLIENT_CONN_PRELOAD,
+			gettext_noop("Lists unprivileged shared libraries to preload into each backend."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE
+		},
+		&local_preload_libraries_string,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"search_path", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the schema search order for names that are not schema-qualified."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_EXPLAIN
+		},
+		&namespace_search_path,
+		"\"$user\", public",
+		check_search_path, assign_search_path, NULL
+	},
+
+	{
+		/* Can't be set in postgresql.conf */
+		{"server_encoding", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the server (database) character set encoding."),
+			NULL,
+			GUC_IS_NAME | GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&server_encoding_string,
+		"SQL_ASCII",
+		NULL, NULL, NULL
+	},
+
+	{
+		/* Can't be set in postgresql.conf */
+		{"server_version", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the server version."),
+			NULL,
+			GUC_REPORT | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&server_version_string,
+		PG_VERSION,
+		NULL, NULL, NULL
+	},
+
+	{
+		/* Not for general use --- used by SET ROLE */
+		{"role", PGC_USERSET, UNGROUPED,
+			gettext_noop("Sets the current role."),
+			NULL,
+			GUC_IS_NAME | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
+		},
+		&role_string,
+		"none",
+		check_role, assign_role, show_role
+	},
+
+	{
+		/* Not for general use --- used by SET SESSION AUTHORIZATION */
+		{"session_authorization", PGC_USERSET, UNGROUPED,
+			gettext_noop("Sets the session user name."),
+			NULL,
+			GUC_IS_NAME | GUC_REPORT | GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_NOT_WHILE_SEC_REST
+		},
+		&session_authorization_string,
+		NULL,
+		check_session_authorization, assign_session_authorization, NULL
+	},
+
+	{
+		{"log_destination", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the destination for server log output."),
+			gettext_noop("Valid values are combinations of \"stderr\", "
+						 "\"syslog\", \"csvlog\", and \"eventlog\", "
+						 "depending on the platform."),
+			GUC_LIST_INPUT
+		},
+		&Log_destination_string,
+		"stderr",
+		check_log_destination, assign_log_destination, NULL
+	},
+	{
+		{"log_directory", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the destination directory for log files."),
+			gettext_noop("Can be specified as relative to the data directory "
+						 "or as absolute path."),
+			GUC_SUPERUSER_ONLY
+		},
+		&Log_directory,
+		"log",
+		check_canonical_path, NULL, NULL
+	},
+	{
+		{"log_filename", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the file name pattern for log files."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&Log_filename,
+		"postgresql-%Y-%m-%d_%H%M%S.log",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"syslog_ident", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the program name used to identify PostgreSQL "
+						 "messages in syslog."),
+			NULL
+		},
+		&syslog_ident_str,
+		"postgres",
+		NULL, assign_syslog_ident, NULL
+	},
+
+	{
+		{"event_source", PGC_POSTMASTER, LOGGING_WHERE,
+			gettext_noop("Sets the application name used to identify "
+						 "PostgreSQL messages in the event log."),
+			NULL
+		},
+		&event_source,
+		DEFAULT_EVENT_SOURCE,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"TimeZone", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the time zone for displaying and interpreting time stamps."),
+			NULL,
+			GUC_REPORT
+		},
+		&timezone_string,
+		"GMT",
+		check_timezone, assign_timezone, show_timezone
+	},
+	{
+		{"timezone_abbreviations", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Selects a file of time zone abbreviations."),
+			NULL
+		},
+		&timezone_abbreviations_string,
+		NULL,
+		check_timezone_abbreviations, assign_timezone_abbreviations, NULL
+	},
+
+	{
+		{"unix_socket_group", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the owning group of the Unix-domain socket."),
+			gettext_noop("The owning user of the socket is always the user "
+						 "that starts the server.")
+		},
+		&Unix_socket_group,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"unix_socket_directories", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the directories where Unix-domain sockets will be created."),
+			NULL,
+			GUC_LIST_INPUT | GUC_LIST_QUOTE | GUC_SUPERUSER_ONLY
+		},
+		&Unix_socket_directories,
+#ifdef HAVE_UNIX_SOCKETS
+		DEFAULT_PGSOCKET_DIR,
+#else
+		"",
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"listen_addresses", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
+			gettext_noop("Sets the host name or IP address(es) to listen to."),
+			NULL,
+			GUC_LIST_INPUT
+		},
+		&ListenAddresses,
+		"localhost",
+		NULL, NULL, NULL
+	},
+
+	{
+		/*
+		 * Can't be set by ALTER SYSTEM as it can lead to recursive definition
+		 * of data_directory.
+		 */
+		{"data_directory", PGC_POSTMASTER, FILE_LOCATIONS,
+			gettext_noop("Sets the server's data directory."),
+			NULL,
+			GUC_SUPERUSER_ONLY | GUC_DISALLOW_IN_AUTO_FILE
+		},
+		&data_directory,
+		NULL,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"config_file", PGC_POSTMASTER, FILE_LOCATIONS,
+			gettext_noop("Sets the server's main configuration file."),
+			NULL,
+			GUC_DISALLOW_IN_FILE | GUC_SUPERUSER_ONLY
+		},
+		&ConfigFileName,
+		NULL,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"hba_file", PGC_POSTMASTER, FILE_LOCATIONS,
+			gettext_noop("Sets the server's \"hba\" configuration file."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&HbaFileName,
+		NULL,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ident_file", PGC_POSTMASTER, FILE_LOCATIONS,
+			gettext_noop("Sets the server's \"ident\" configuration file."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&IdentFileName,
+		NULL,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"external_pid_file", PGC_POSTMASTER, FILE_LOCATIONS,
+			gettext_noop("Writes the postmaster PID to the specified file."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&external_pid_file,
+		NULL,
+		check_canonical_path, NULL, NULL
+	},
+
+	{
+		{"ssl_library", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows the name of the SSL library."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&ssl_library,
+#ifdef USE_SSL
+		"OpenSSL",
+#else
+		"",
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_cert_file", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL server certificate file."),
+			NULL
+		},
+		&ssl_cert_file,
+		"server.crt",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_key_file", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL server private key file."),
+			NULL
+		},
+		&ssl_key_file,
+		"server.key",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_ca_file", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL certificate authority file."),
+			NULL
+		},
+		&ssl_ca_file,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_crl_file", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL certificate revocation list file."),
+			NULL
+		},
+		&ssl_crl_file,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_crl_dir", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL certificate revocation list directory."),
+			NULL
+		},
+		&ssl_crl_dir,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"stats_temp_directory", PGC_SIGHUP, STATS_COLLECTOR,
+			gettext_noop("Writes temporary statistics files to the specified directory."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&pgstat_temp_directory,
+		PG_STAT_TMP_DIR,
+		check_canonical_path, assign_pgstat_temp_directory, NULL
+	},
+
+	{
+		{"synchronous_standby_names", PGC_SIGHUP, REPLICATION_PRIMARY,
+			gettext_noop("Number of synchronous standbys and list of names of potential synchronous ones."),
+			NULL,
+			GUC_LIST_INPUT
+		},
+		&SyncRepStandbyNames,
+		"",
+		check_synchronous_standby_names, assign_synchronous_standby_names, NULL
+	},
+
+	{
+		{"default_text_search_config", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets default text search configuration."),
+			NULL
+		},
+		&TSCurrentConfig,
+		"pg_catalog.simple",
+		check_TSCurrentConfig, assign_TSCurrentConfig, NULL
+	},
+
+	{
+		{"ssl_ciphers", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Sets the list of allowed SSL ciphers."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&SSLCipherSuites,
+#ifdef USE_OPENSSL
+		"HIGH:MEDIUM:+3DES:!aNULL",
+#else
+		"none",
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_ecdh_curve", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Sets the curve to use for ECDH."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&SSLECDHCurve,
+#ifdef USE_SSL
+		"prime256v1",
+#else
+		"none",
+#endif
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_dh_params_file", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Location of the SSL DH parameters file."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&ssl_dh_params_file,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_passphrase_command", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Command to obtain passphrases for SSL."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&ssl_passphrase_command,
+		"",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"application_name", PGC_USERSET, LOGGING_WHAT,
+			gettext_noop("Sets the application name to be reported in statistics and logs."),
+			NULL,
+			GUC_IS_NAME | GUC_REPORT | GUC_NOT_IN_SAMPLE
+		},
+		&application_name,
+		"",
+		check_application_name, assign_application_name, NULL
+	},
+
+	{
+		{"cluster_name", PGC_POSTMASTER, PROCESS_TITLE,
+			gettext_noop("Sets the name of the cluster, which is included in the process title."),
+			NULL,
+			GUC_IS_NAME
+		},
+		&cluster_name,
+		"",
+		check_cluster_name, NULL, NULL
+	},
+
+	{
+		{"wal_consistency_checking", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Sets the WAL resource managers for which WAL consistency checks are done."),
+			gettext_noop("Full-page images will be logged for all data blocks and cross-checked against the results of WAL replay."),
+			GUC_LIST_INPUT | GUC_NOT_IN_SAMPLE
+		},
+		&wal_consistency_checking_string,
+		"",
+		check_wal_consistency_checking, assign_wal_consistency_checking, NULL
+	},
+
+	{
+		{"jit_provider", PGC_POSTMASTER, CLIENT_CONN_PRELOAD,
+			gettext_noop("JIT provider to use."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&jit_provider,
+		"llvmjit",
+		NULL, NULL, NULL
+	},
+
+	{
+		{"backtrace_functions", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Log backtrace for errors in these functions."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&backtrace_functions,
+		"",
+		check_backtrace_functions, assign_backtrace_functions, NULL
+	},
+
+	/* End-of-list marker */
+	{
+		{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL
+	}
+};
+
+
+static struct config_enum ConfigureNamesEnum[] =
+{
+	{
+		{"backslash_quote", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+			gettext_noop("Sets whether \"\\'\" is allowed in string literals."),
+			NULL
+		},
+		&backslash_quote,
+		BACKSLASH_QUOTE_SAFE_ENCODING, backslash_quote_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"bytea_output", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the output format for bytea."),
+			NULL
+		},
+		&bytea_output,
+		BYTEA_OUTPUT_HEX, bytea_output_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"client_min_messages", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the message levels that are sent to the client."),
+			gettext_noop("Each level includes all the levels that follow it. The later"
+						 " the level, the fewer messages are sent.")
+		},
+		&client_min_messages,
+		NOTICE, client_message_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"compute_query_id", PGC_SUSET, STATS_MONITORING,
+			gettext_noop("Compute query identifiers."),
+			NULL
+		},
+		&compute_query_id,
+		COMPUTE_QUERY_ID_AUTO, compute_query_id_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"constraint_exclusion", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Enables the planner to use constraints to optimize queries."),
+			gettext_noop("Table scans will be skipped if their constraints"
+						 " guarantee that no rows match the query."),
+			GUC_EXPLAIN
+		},
+		&constraint_exclusion,
+		CONSTRAINT_EXCLUSION_PARTITION, constraint_exclusion_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"default_toast_compression", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the default compression method for compressible values."),
+			NULL
+		},
+		&default_toast_compression,
+		TOAST_PGLZ_COMPRESSION,
+		default_toast_compression_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"default_transaction_isolation", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the transaction isolation level of each new transaction."),
+			NULL
+		},
+		&DefaultXactIsoLevel,
+		XACT_READ_COMMITTED, isolation_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"transaction_isolation", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the current transaction's isolation level."),
+			NULL,
+			GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&XactIsoLevel,
+		XACT_READ_COMMITTED, isolation_level_options,
+		check_XactIsoLevel, NULL, NULL
+	},
+
+	{
+		{"IntervalStyle", PGC_USERSET, CLIENT_CONN_LOCALE,
+			gettext_noop("Sets the display format for interval values."),
+			NULL,
+			GUC_REPORT
+		},
+		&IntervalStyle,
+		INTSTYLE_POSTGRES, intervalstyle_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_error_verbosity", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Sets the verbosity of logged messages."),
+			NULL
+		},
+		&Log_error_verbosity,
+		PGERROR_DEFAULT, log_error_verbosity_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_min_messages", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Sets the message levels that are logged."),
+			gettext_noop("Each level includes all the levels that follow it. The later"
+						 " the level, the fewer messages are sent.")
+		},
+		&log_min_messages,
+		WARNING, server_message_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_min_error_statement", PGC_SUSET, LOGGING_WHEN,
+			gettext_noop("Causes all statements generating error at or above this level to be logged."),
+			gettext_noop("Each level includes all the levels that follow it. The later"
+						 " the level, the fewer messages are sent.")
+		},
+		&log_min_error_statement,
+		ERROR, server_message_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"log_statement", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Sets the type of statements logged."),
+			NULL
+		},
+		&log_statement,
+		LOGSTMT_NONE, log_statement_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"syslog_facility", PGC_SIGHUP, LOGGING_WHERE,
+			gettext_noop("Sets the syslog \"facility\" to be used when syslog enabled."),
+			NULL
+		},
+		&syslog_facility,
+#ifdef HAVE_SYSLOG
+		LOG_LOCAL0,
+#else
+		0,
+#endif
+		syslog_facility_options,
+		NULL, assign_syslog_facility, NULL
+	},
+
+	{
+		{"session_replication_role", PGC_SUSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the session's behavior for triggers and rewrite rules."),
+			NULL
+		},
+		&SessionReplicationRole,
+		SESSION_REPLICATION_ROLE_ORIGIN, session_replication_role_options,
+		NULL, assign_session_replication_role, NULL
+	},
+
+	{
+		{"synchronous_commit", PGC_USERSET, WAL_SETTINGS,
+			gettext_noop("Sets the current transaction's synchronization level."),
+			NULL
+		},
+		&synchronous_commit,
+		SYNCHRONOUS_COMMIT_ON, synchronous_commit_options,
+		NULL, assign_synchronous_commit, NULL
+	},
+
+	{
+		{"archive_mode", PGC_POSTMASTER, WAL_ARCHIVING,
+			gettext_noop("Allows archiving of WAL files using archive_command."),
+			NULL
+		},
+		&XLogArchiveMode,
+		ARCHIVE_MODE_OFF, archive_mode_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_target_action", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
+			gettext_noop("Sets the action to perform upon reaching the recovery target."),
+			NULL
+		},
+		&recoveryTargetAction,
+		RECOVERY_TARGET_ACTION_PAUSE, recovery_target_action_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"trace_recovery_messages", PGC_SIGHUP, DEVELOPER_OPTIONS,
+			gettext_noop("Enables logging of recovery-related debugging information."),
+			gettext_noop("Each level includes all the levels that follow it. The later"
+						 " the level, the fewer messages are sent.")
+		},
+		&trace_recovery_messages,
+
+		/*
+		 * client_message_level_options allows too many values, really, but
+		 * it's not worth having a separate options array for this.
+		 */
+		LOG, client_message_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"track_functions", PGC_SUSET, STATS_COLLECTOR,
+			gettext_noop("Collects function-level statistics on database activity."),
+			NULL
+		},
+		&pgstat_track_functions,
+		TRACK_FUNC_OFF, track_function_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_level", PGC_POSTMASTER, WAL_SETTINGS,
+			gettext_noop("Sets the level of information written to the WAL."),
+			NULL
+		},
+		&wal_level,
+		WAL_LEVEL_REPLICA, wal_level_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"dynamic_shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Selects the dynamic shared memory implementation used."),
+			NULL
+		},
+		&dynamic_shared_memory_type,
+		DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE, dynamic_shared_memory_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Selects the shared memory implementation used for the main shared memory region."),
+			NULL
+		},
+		&shared_memory_type,
+		DEFAULT_SHARED_MEMORY_TYPE, shared_memory_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
+			gettext_noop("Selects the method used for forcing WAL updates to disk."),
+			NULL
+		},
+		&sync_method,
+		DEFAULT_SYNC_METHOD, sync_method_options,
+		NULL, assign_xlog_sync_method, NULL
+	},
+
+	{
+		{"xmlbinary", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets how binary values are to be encoded in XML."),
+			NULL
+		},
+		&xmlbinary,
+		XMLBINARY_BASE64, xmlbinary_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"xmloption", PGC_USERSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets whether XML data in implicit parsing and serialization "
+						 "operations is to be considered as documents or content fragments."),
+			NULL
+		},
+		&xmloption,
+		XMLOPTION_CONTENT, xmloption_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"huge_pages", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Use of huge pages on Linux or Windows."),
+			NULL
+		},
+		&huge_pages,
+		HUGE_PAGES_TRY, huge_pages_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"force_parallel_mode", PGC_USERSET, DEVELOPER_OPTIONS,
+			gettext_noop("Forces use of parallel query facilities."),
+			gettext_noop("If possible, run query using a parallel worker and with parallel restrictions."),
+			GUC_NOT_IN_SAMPLE | GUC_EXPLAIN
+		},
+		&force_parallel_mode,
+		FORCE_PARALLEL_OFF, force_parallel_mode_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"password_encryption", PGC_USERSET, CONN_AUTH_AUTH,
+			gettext_noop("Chooses the algorithm for encrypting passwords."),
+			NULL
+		},
+		&Password_encryption,
+		PASSWORD_TYPE_SCRAM_SHA_256, password_encryption_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"plan_cache_mode", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Controls the planner's selection of custom or generic plan."),
+			gettext_noop("Prepared statements can have custom and generic plans, and the planner "
+						 "will attempt to choose which is better.  This can be set to override "
+						 "the default behavior."),
+			GUC_EXPLAIN
+		},
+		&plan_cache_mode,
+		PLAN_CACHE_MODE_AUTO, plan_cache_mode_options,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_min_protocol_version", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Sets the minimum SSL/TLS protocol version to use."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&ssl_min_protocol_version,
+		PG_TLS1_2_VERSION,
+		ssl_protocol_versions_info + 1, /* don't allow PG_TLS_ANY */
+		NULL, NULL, NULL
+	},
+
+	{
+		{"ssl_max_protocol_version", PGC_SIGHUP, CONN_AUTH_SSL,
+			gettext_noop("Sets the maximum SSL/TLS protocol version to use."),
+			NULL,
+			GUC_SUPERUSER_ONLY
+		},
+		&ssl_max_protocol_version,
+		PG_TLS_ANY,
+		ssl_protocol_versions_info,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"recovery_init_sync_method", PGC_SIGHUP, ERROR_HANDLING_OPTIONS,
+			gettext_noop("Sets the method for synchronizing the data directory before crash recovery."),
+		},
+		&recovery_init_sync_method,
+		RECOVERY_INIT_SYNC_METHOD_FSYNC, recovery_init_sync_method_options,
+		NULL, NULL, NULL
+	},
+
+	/* End-of-list marker */
+	{
+		{NULL, 0, 0, NULL, NULL}, NULL, 0, NULL, NULL, NULL, NULL
+	}
+};
+
+/******** end of options list ********/
+
+
+/*
+ * To allow continued support of obsolete names for GUC variables, we apply
+ * the following mappings to any unrecognized name.  Note that an old name
+ * should be mapped to a new one only if the new variable has very similar
+ * semantics to the old.
+ */
+static const char *const map_old_guc_names[] = {
+	"sort_mem", "work_mem",
+	"vacuum_mem", "maintenance_work_mem",
+	NULL
+};
+
+
+/*
+ * Actual lookup of variables is done through this single, sorted array.
+ */
+static struct config_generic **guc_variables;
+
+/* Current number of variables contained in the vector */
+static int	num_guc_variables;
+
+/* Vector capacity */
+static int	size_guc_variables;
+
+
+static bool guc_dirty;			/* true if need to do commit/abort work */
+
+static bool reporting_enabled;	/* true to enable GUC_REPORT */
+
+static bool report_needed;		/* true if any GUC_REPORT reports are needed */
+
+static int	GUCNestLevel = 0;	/* 1 when in main transaction */
+
+
+static int	guc_var_compare(const void *a, const void *b);
+static int	guc_name_compare(const char *namea, const char *nameb);
+static void InitializeGUCOptionsFromEnvironment(void);
+static void InitializeOneGUCOption(struct config_generic *gconf);
+static void push_old_value(struct config_generic *gconf, GucAction action);
+static void ReportGUCOption(struct config_generic *record);
+static void reapply_stacked_values(struct config_generic *variable,
+								   struct config_string *pHolder,
+								   GucStack *stack,
+								   const char *curvalue,
+								   GucContext curscontext, GucSource cursource);
+static void ShowGUCConfigOption(const char *name, DestReceiver *dest);
+static void ShowAllGUCConfig(DestReceiver *dest);
+static char *_ShowOption(struct config_generic *record, bool use_units);
+static bool validate_option_array_item(const char *name, const char *value,
+									   bool skipIfNoPermissions);
+static void write_auto_conf_file(int fd, const char *filename, ConfigVariable *head_p);
+static void replace_auto_config_value(ConfigVariable **head_p, ConfigVariable **tail_p,
+									  const char *name, const char *value);
+
+
+/*
+ * Some infrastructure for checking malloc/strdup/realloc calls
+ */
+static void *
+guc_malloc(int elevel, size_t size)
+{
+	void	   *data;
+
+	/* Avoid unportable behavior of malloc(0) */
+	if (size == 0)
+		size = 1;
+	data = malloc(size);
+	if (data == NULL)
+		ereport(elevel,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+	return data;
+}
+
+static void *
+guc_realloc(int elevel, void *old, size_t size)
+{
+	void	   *data;
+
+	/* Avoid unportable behavior of realloc(NULL, 0) */
+	if (old == NULL && size == 0)
+		size = 1;
+	data = realloc(old, size);
+	if (data == NULL)
+		ereport(elevel,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+	return data;
+}
+
+static char *
+guc_strdup(int elevel, const char *src)
+{
+	char	   *data;
+
+	data = strdup(src);
+	if (data == NULL)
+		ereport(elevel,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory")));
+	return data;
+}
+
+
+/*
+ * Detect whether strval is referenced anywhere in a GUC string item
+ */
+static bool
+string_field_used(struct config_string *conf, char *strval)
+{
+	GucStack   *stack;
+
+	if (strval == *(conf->variable) ||
+		strval == conf->reset_val ||
+		strval == conf->boot_val)
+		return true;
+	for (stack = conf->gen.stack; stack; stack = stack->prev)
+	{
+		if (strval == stack->prior.val.stringval ||
+			strval == stack->masked.val.stringval)
+			return true;
+	}
+	return false;
+}
+
+/*
+ * Support for assigning to a field of a string GUC item.  Free the prior
+ * value if it's not referenced anywhere else in the item (including stacked
+ * states).
+ */
+static void
+set_string_field(struct config_string *conf, char **field, char *newval)
+{
+	char	   *oldval = *field;
+
+	/* Do the assignment */
+	*field = newval;
+
+	/* Free old value if it's not NULL and isn't referenced anymore */
+	if (oldval && !string_field_used(conf, oldval))
+		free(oldval);
+}
+
+/*
+ * Detect whether an "extra" struct is referenced anywhere in a GUC item
+ */
+static bool
+extra_field_used(struct config_generic *gconf, void *extra)
+{
+	GucStack   *stack;
+
+	if (extra == gconf->extra)
+		return true;
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			if (extra == ((struct config_bool *) gconf)->reset_extra)
+				return true;
+			break;
+		case PGC_INT:
+			if (extra == ((struct config_int *) gconf)->reset_extra)
+				return true;
+			break;
+		case PGC_REAL:
+			if (extra == ((struct config_real *) gconf)->reset_extra)
+				return true;
+			break;
+		case PGC_STRING:
+			if (extra == ((struct config_string *) gconf)->reset_extra)
+				return true;
+			break;
+		case PGC_ENUM:
+			if (extra == ((struct config_enum *) gconf)->reset_extra)
+				return true;
+			break;
+	}
+	for (stack = gconf->stack; stack; stack = stack->prev)
+	{
+		if (extra == stack->prior.extra ||
+			extra == stack->masked.extra)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * Support for assigning to an "extra" field of a GUC item.  Free the prior
+ * value if it's not referenced anywhere else in the item (including stacked
+ * states).
+ */
+static void
+set_extra_field(struct config_generic *gconf, void **field, void *newval)
+{
+	void	   *oldval = *field;
+
+	/* Do the assignment */
+	*field = newval;
+
+	/* Free old value if it's not NULL and isn't referenced anymore */
+	if (oldval && !extra_field_used(gconf, oldval))
+		free(oldval);
+}
+
+/*
+ * Support for copying a variable's active value into a stack entry.
+ * The "extra" field associated with the active value is copied, too.
+ *
+ * NB: be sure stringval and extra fields of a new stack entry are
+ * initialized to NULL before this is used, else we'll try to free() them.
+ */
+static void
+set_stack_value(struct config_generic *gconf, config_var_value *val)
+{
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			val->val.boolval =
+				*((struct config_bool *) gconf)->variable;
+			break;
+		case PGC_INT:
+			val->val.intval =
+				*((struct config_int *) gconf)->variable;
+			break;
+		case PGC_REAL:
+			val->val.realval =
+				*((struct config_real *) gconf)->variable;
+			break;
+		case PGC_STRING:
+			set_string_field((struct config_string *) gconf,
+							 &(val->val.stringval),
+							 *((struct config_string *) gconf)->variable);
+			break;
+		case PGC_ENUM:
+			val->val.enumval =
+				*((struct config_enum *) gconf)->variable;
+			break;
+	}
+	set_extra_field(gconf, &(val->extra), gconf->extra);
+}
+
+/*
+ * Support for discarding a no-longer-needed value in a stack entry.
+ * The "extra" field associated with the stack entry is cleared, too.
+ */
+static void
+discard_stack_value(struct config_generic *gconf, config_var_value *val)
+{
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+		case PGC_INT:
+		case PGC_REAL:
+		case PGC_ENUM:
+			/* no need to do anything */
+			break;
+		case PGC_STRING:
+			set_string_field((struct config_string *) gconf,
+							 &(val->val.stringval),
+							 NULL);
+			break;
+	}
+	set_extra_field(gconf, &(val->extra), NULL);
+}
+
+
+/*
+ * Fetch the sorted array pointer (exported for help_config.c's use ONLY)
+ */
+struct config_generic **
+get_guc_variables(void)
+{
+	return guc_variables;
+}
+
+
+/*
+ * Build the sorted array.  This is split out so that it could be
+ * re-executed after startup (e.g., we could allow loadable modules to
+ * add vars, and then we'd need to re-sort).
+ */
+void
+build_guc_variables(void)
+{
+	int			size_vars;
+	int			num_vars = 0;
+	struct config_generic **guc_vars;
+	int			i;
+
+	for (i = 0; ConfigureNamesBool[i].gen.name; i++)
+	{
+		struct config_bool *conf = &ConfigureNamesBool[i];
+
+		/* Rather than requiring vartype to be filled in by hand, do this: */
+		conf->gen.vartype = PGC_BOOL;
+		num_vars++;
+	}
+
+	for (i = 0; ConfigureNamesInt[i].gen.name; i++)
+	{
+		struct config_int *conf = &ConfigureNamesInt[i];
+
+		conf->gen.vartype = PGC_INT;
+		num_vars++;
+	}
+
+	for (i = 0; ConfigureNamesReal[i].gen.name; i++)
+	{
+		struct config_real *conf = &ConfigureNamesReal[i];
+
+		conf->gen.vartype = PGC_REAL;
+		num_vars++;
+	}
+
+	for (i = 0; ConfigureNamesString[i].gen.name; i++)
+	{
+		struct config_string *conf = &ConfigureNamesString[i];
+
+		conf->gen.vartype = PGC_STRING;
+		num_vars++;
+	}
+
+	for (i = 0; ConfigureNamesEnum[i].gen.name; i++)
+	{
+		struct config_enum *conf = &ConfigureNamesEnum[i];
+
+		conf->gen.vartype = PGC_ENUM;
+		num_vars++;
+	}
+
+	/*
+	 * Create table with 20% slack
+	 */
+	size_vars = num_vars + num_vars / 4;
+
+	guc_vars = (struct config_generic **)
+		guc_malloc(FATAL, size_vars * sizeof(struct config_generic *));
+
+	num_vars = 0;
+
+	for (i = 0; ConfigureNamesBool[i].gen.name; i++)
+		guc_vars[num_vars++] = &ConfigureNamesBool[i].gen;
+
+	for (i = 0; ConfigureNamesInt[i].gen.name; i++)
+		guc_vars[num_vars++] = &ConfigureNamesInt[i].gen;
+
+	for (i = 0; ConfigureNamesReal[i].gen.name; i++)
+		guc_vars[num_vars++] = &ConfigureNamesReal[i].gen;
+
+	for (i = 0; ConfigureNamesString[i].gen.name; i++)
+		guc_vars[num_vars++] = &ConfigureNamesString[i].gen;
+
+	for (i = 0; ConfigureNamesEnum[i].gen.name; i++)
+		guc_vars[num_vars++] = &ConfigureNamesEnum[i].gen;
+
+	if (guc_variables)
+		free(guc_variables);
+	guc_variables = guc_vars;
+	num_guc_variables = num_vars;
+	size_guc_variables = size_vars;
+	qsort((void *) guc_variables, num_guc_variables,
+		  sizeof(struct config_generic *), guc_var_compare);
+}
+
+/*
+ * Add a new GUC variable to the list of known variables. The
+ * list is expanded if needed.
+ */
+static bool
+add_guc_variable(struct config_generic *var, int elevel)
+{
+	if (num_guc_variables + 1 >= size_guc_variables)
+	{
+		/*
+		 * Increase the vector by 25%
+		 */
+		int			size_vars = size_guc_variables + size_guc_variables / 4;
+		struct config_generic **guc_vars;
+
+		if (size_vars == 0)
+		{
+			size_vars = 100;
+			guc_vars = (struct config_generic **)
+				guc_malloc(elevel, size_vars * sizeof(struct config_generic *));
+		}
+		else
+		{
+			guc_vars = (struct config_generic **)
+				guc_realloc(elevel, guc_variables, size_vars * sizeof(struct config_generic *));
+		}
+
+		if (guc_vars == NULL)
+			return false;		/* out of memory */
+
+		guc_variables = guc_vars;
+		size_guc_variables = size_vars;
+	}
+	guc_variables[num_guc_variables++] = var;
+	qsort((void *) guc_variables, num_guc_variables,
+		  sizeof(struct config_generic *), guc_var_compare);
+	return true;
+}
+
+/*
+ * Decide whether a proposed custom variable name is allowed.
+ *
+ * It must be two or more identifiers separated by dots, where the rules
+ * for what is an identifier agree with scan.l.  (If you change this rule,
+ * adjust the errdetail in find_option().)
+ */
+static bool
+valid_custom_variable_name(const char *name)
+{
+	bool		saw_sep = false;
+	bool		name_start = true;
+
+	for (const char *p = name; *p; p++)
+	{
+		if (*p == GUC_QUALIFIER_SEPARATOR)
+		{
+			if (name_start)
+				return false;	/* empty name component */
+			saw_sep = true;
+			name_start = true;
+		}
+		else if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+						"abcdefghijklmnopqrstuvwxyz_", *p) != NULL ||
+				 IS_HIGHBIT_SET(*p))
+		{
+			/* okay as first or non-first character */
+			name_start = false;
+		}
+		else if (!name_start && strchr("0123456789$", *p) != NULL)
+			 /* okay as non-first character */ ;
+		else
+			return false;
+	}
+	if (name_start)
+		return false;			/* empty name component */
+	/* OK if we found at least one separator */
+	return saw_sep;
+}
+
+/*
+ * Create and add a placeholder variable for a custom variable name.
+ */
+static struct config_generic *
+add_placeholder_variable(const char *name, int elevel)
+{
+	size_t		sz = sizeof(struct config_string) + sizeof(char *);
+	struct config_string *var;
+	struct config_generic *gen;
+
+	var = (struct config_string *) guc_malloc(elevel, sz);
+	if (var == NULL)
+		return NULL;
+	memset(var, 0, sz);
+	gen = &var->gen;
+
+	gen->name = guc_strdup(elevel, name);
+	if (gen->name == NULL)
+	{
+		free(var);
+		return NULL;
+	}
+
+	gen->context = PGC_USERSET;
+	gen->group = CUSTOM_OPTIONS;
+	gen->short_desc = "GUC placeholder variable";
+	gen->flags = GUC_NO_SHOW_ALL | GUC_NOT_IN_SAMPLE | GUC_CUSTOM_PLACEHOLDER;
+	gen->vartype = PGC_STRING;
+
+	/*
+	 * The char* is allocated at the end of the struct since we have no
+	 * 'static' place to point to.  Note that the current value, as well as
+	 * the boot and reset values, start out NULL.
+	 */
+	var->variable = (char **) (var + 1);
+
+	if (!add_guc_variable((struct config_generic *) var, elevel))
+	{
+		free(unconstify(char *, gen->name));
+		free(var);
+		return NULL;
+	}
+
+	return gen;
+}
+
+/*
+ * Look up option "name".  If it exists, return a pointer to its record.
+ * Otherwise, if create_placeholders is true and name is a valid-looking
+ * custom variable name, we'll create and return a placeholder record.
+ * Otherwise, if skip_errors is true, then we silently return NULL for
+ * an unrecognized or invalid name.  Otherwise, the error is reported at
+ * error level elevel (and we return NULL if that's less than ERROR).
+ *
+ * Note: internal errors, primarily out-of-memory, draw an elevel-level
+ * report and NULL return regardless of skip_errors.  Hence, callers must
+ * handle a NULL return whenever elevel < ERROR, but they should not need
+ * to emit any additional error message.  (In practice, internal errors
+ * can only happen when create_placeholders is true, so callers passing
+ * false need not think terribly hard about this.)
+ */
+static struct config_generic *
+find_option(const char *name, bool create_placeholders, bool skip_errors,
+			int elevel)
+{
+	const char **key = &name;
+	struct config_generic **res;
+	int			i;
+
+	Assert(name);
+
+	/*
+	 * By equating const char ** with struct config_generic *, we are assuming
+	 * the name field is first in config_generic.
+	 */
+	res = (struct config_generic **) bsearch((void *) &key,
+											 (void *) guc_variables,
+											 num_guc_variables,
+											 sizeof(struct config_generic *),
+											 guc_var_compare);
+	if (res)
+		return *res;
+
+	/*
+	 * See if the name is an obsolete name for a variable.  We assume that the
+	 * set of supported old names is short enough that a brute-force search is
+	 * the best way.
+	 */
+	for (i = 0; map_old_guc_names[i] != NULL; i += 2)
+	{
+		if (guc_name_compare(name, map_old_guc_names[i]) == 0)
+			return find_option(map_old_guc_names[i + 1], false,
+							   skip_errors, elevel);
+	}
+
+	if (create_placeholders)
+	{
+		/*
+		 * Check if the name is valid, and if so, add a placeholder.  If it
+		 * doesn't contain a separator, don't assume that it was meant to be a
+		 * placeholder.
+		 */
+		if (strchr(name, GUC_QUALIFIER_SEPARATOR) != NULL)
+		{
+			if (valid_custom_variable_name(name))
+				return add_placeholder_variable(name, elevel);
+			/* A special error message seems desirable here */
+			if (!skip_errors)
+				ereport(elevel,
+						(errcode(ERRCODE_INVALID_NAME),
+						 errmsg("invalid configuration parameter name \"%s\"",
+								name),
+						 errdetail("Custom parameter names must be two or more simple identifiers separated by dots.")));
+			return NULL;
+		}
+	}
+
+	/* Unknown name */
+	if (!skip_errors)
+		ereport(elevel,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("unrecognized configuration parameter \"%s\"",
+						name)));
+	return NULL;
+}
+
+
+/*
+ * comparator for qsorting and bsearching guc_variables array
+ */
+static int
+guc_var_compare(const void *a, const void *b)
+{
+	const struct config_generic *confa = *(struct config_generic *const *) a;
+	const struct config_generic *confb = *(struct config_generic *const *) b;
+
+	return guc_name_compare(confa->name, confb->name);
+}
+
+/*
+ * the bare comparison function for GUC names
+ */
+static int
+guc_name_compare(const char *namea, const char *nameb)
+{
+	/*
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
+	 */
+	while (*namea && *nameb)
+	{
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
+	}
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
+}
+
+
+/*
+ * Initialize GUC options during program startup.
+ *
+ * Note that we cannot read the config file yet, since we have not yet
+ * processed command-line switches.
+ */
+void
+InitializeGUCOptions(void)
+{
+	int			i;
+
+	/*
+	 * Before log_line_prefix could possibly receive a nonempty setting, make
+	 * sure that timezone processing is minimally alive (see elog.c).
+	 */
+	pg_timezone_initialize();
+
+	/*
+	 * Build sorted array of all GUC variables.
+	 */
+	build_guc_variables();
+
+	/*
+	 * Load all variables with their compiled-in defaults, and initialize
+	 * status fields as needed.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		InitializeOneGUCOption(guc_variables[i]);
+	}
+
+	guc_dirty = false;
+
+	reporting_enabled = false;
+
+	/*
+	 * Prevent any attempt to override the transaction modes from
+	 * non-interactive sources.
+	 */
+	SetConfigOption("transaction_isolation", "read committed",
+					PGC_POSTMASTER, PGC_S_OVERRIDE);
+	SetConfigOption("transaction_read_only", "no",
+					PGC_POSTMASTER, PGC_S_OVERRIDE);
+	SetConfigOption("transaction_deferrable", "no",
+					PGC_POSTMASTER, PGC_S_OVERRIDE);
+
+	/*
+	 * For historical reasons, some GUC parameters can receive defaults from
+	 * environment variables.  Process those settings.
+	 */
+	InitializeGUCOptionsFromEnvironment();
+}
+
+/*
+ * Assign any GUC values that can come from the server's environment.
+ *
+ * This is called from InitializeGUCOptions, and also from ProcessConfigFile
+ * to deal with the possibility that a setting has been removed from
+ * postgresql.conf and should now get a value from the environment.
+ * (The latter is a kludge that should probably go away someday; if so,
+ * fold this back into InitializeGUCOptions.)
+ */
+static void
+InitializeGUCOptionsFromEnvironment(void)
+{
+	char	   *env;
+	long		stack_rlimit;
+
+	env = getenv("PGPORT");
+	if (env != NULL)
+		SetConfigOption("port", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
+
+	env = getenv("PGDATESTYLE");
+	if (env != NULL)
+		SetConfigOption("datestyle", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
+
+	env = getenv("PGCLIENTENCODING");
+	if (env != NULL)
+		SetConfigOption("client_encoding", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
+
+	/*
+	 * rlimit isn't exactly an "environment variable", but it behaves about
+	 * the same.  If we can identify the platform stack depth rlimit, increase
+	 * default stack depth setting up to whatever is safe (but at most 2MB).
+	 */
+	stack_rlimit = get_stack_depth_rlimit();
+	if (stack_rlimit > 0)
+	{
+		long		new_limit = (stack_rlimit - STACK_DEPTH_SLOP) / 1024L;
+
+		if (new_limit > 100)
+		{
+			char		limbuf[16];
+
+			new_limit = Min(new_limit, 2048);
+			sprintf(limbuf, "%ld", new_limit);
+			SetConfigOption("max_stack_depth", limbuf,
+							PGC_POSTMASTER, PGC_S_ENV_VAR);
+		}
+	}
+}
+
+/*
+ * Initialize one GUC option variable to its compiled-in default.
+ *
+ * Note: the reason for calling check_hooks is not that we think the boot_val
+ * might fail, but that the hooks might wish to compute an "extra" struct.
+ */
+static void
+InitializeOneGUCOption(struct config_generic *gconf)
+{
+	gconf->status = 0;
+	gconf->source = PGC_S_DEFAULT;
+	gconf->reset_source = PGC_S_DEFAULT;
+	gconf->scontext = PGC_INTERNAL;
+	gconf->reset_scontext = PGC_INTERNAL;
+	gconf->stack = NULL;
+	gconf->extra = NULL;
+	gconf->last_reported = NULL;
+	gconf->sourcefile = NULL;
+	gconf->sourceline = 0;
+
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) gconf;
+				bool		newval = conf->boot_val;
+				void	   *extra = NULL;
+
+				if (!call_bool_check_hook(conf, &newval, &extra,
+										  PGC_S_DEFAULT, LOG))
+					elog(FATAL, "failed to initialize %s to %d",
+						 conf->gen.name, (int) newval);
+				if (conf->assign_hook)
+					conf->assign_hook(newval, extra);
+				*conf->variable = conf->reset_val = newval;
+				conf->gen.extra = conf->reset_extra = extra;
+				break;
+			}
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) gconf;
+				int			newval = conf->boot_val;
+				void	   *extra = NULL;
+
+				Assert(newval >= conf->min);
+				Assert(newval <= conf->max);
+				if (!call_int_check_hook(conf, &newval, &extra,
+										 PGC_S_DEFAULT, LOG))
+					elog(FATAL, "failed to initialize %s to %d",
+						 conf->gen.name, newval);
+				if (conf->assign_hook)
+					conf->assign_hook(newval, extra);
+				*conf->variable = conf->reset_val = newval;
+				conf->gen.extra = conf->reset_extra = extra;
+				break;
+			}
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) gconf;
+				double		newval = conf->boot_val;
+				void	   *extra = NULL;
+
+				Assert(newval >= conf->min);
+				Assert(newval <= conf->max);
+				if (!call_real_check_hook(conf, &newval, &extra,
+										  PGC_S_DEFAULT, LOG))
+					elog(FATAL, "failed to initialize %s to %g",
+						 conf->gen.name, newval);
+				if (conf->assign_hook)
+					conf->assign_hook(newval, extra);
+				*conf->variable = conf->reset_val = newval;
+				conf->gen.extra = conf->reset_extra = extra;
+				break;
+			}
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) gconf;
+				char	   *newval;
+				void	   *extra = NULL;
+
+				/* non-NULL boot_val must always get strdup'd */
+				if (conf->boot_val != NULL)
+					newval = guc_strdup(FATAL, conf->boot_val);
+				else
+					newval = NULL;
+
+				if (!call_string_check_hook(conf, &newval, &extra,
+											PGC_S_DEFAULT, LOG))
+					elog(FATAL, "failed to initialize %s to \"%s\"",
+						 conf->gen.name, newval ? newval : "");
+				if (conf->assign_hook)
+					conf->assign_hook(newval, extra);
+				*conf->variable = conf->reset_val = newval;
+				conf->gen.extra = conf->reset_extra = extra;
+				break;
+			}
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) gconf;
+				int			newval = conf->boot_val;
+				void	   *extra = NULL;
+
+				if (!call_enum_check_hook(conf, &newval, &extra,
+										  PGC_S_DEFAULT, LOG))
+					elog(FATAL, "failed to initialize %s to %d",
+						 conf->gen.name, newval);
+				if (conf->assign_hook)
+					conf->assign_hook(newval, extra);
+				*conf->variable = conf->reset_val = newval;
+				conf->gen.extra = conf->reset_extra = extra;
+				break;
+			}
+	}
+}
+
+
+/*
+ * Select the configuration files and data directory to be used, and
+ * do the initial read of postgresql.conf.
+ *
+ * This is called after processing command-line switches.
+ *		userDoption is the -D switch value if any (NULL if unspecified).
+ *		progname is just for use in error messages.
+ *
+ * Returns true on success; on failure, prints a suitable error message
+ * to stderr and returns false.
+ */
+bool
+SelectConfigFiles(const char *userDoption, const char *progname)
+{
+	char	   *configdir;
+	char	   *fname;
+	struct stat stat_buf;
+
+	/* configdir is -D option, or $PGDATA if no -D */
+	if (userDoption)
+		configdir = make_absolute_path(userDoption);
+	else
+		configdir = make_absolute_path(getenv("PGDATA"));
+
+	if (configdir && stat(configdir, &stat_buf) != 0)
+	{
+		write_stderr("%s: could not access directory \"%s\": %s\n",
+					 progname,
+					 configdir,
+					 strerror(errno));
+		if (errno == ENOENT)
+			write_stderr("Run initdb or pg_basebackup to initialize a PostgreSQL data directory.\n");
+		return false;
+	}
+
+	/*
+	 * Find the configuration file: if config_file was specified on the
+	 * command line, use it, else use configdir/postgresql.conf.  In any case
+	 * ensure the result is an absolute path, so that it will be interpreted
+	 * the same way by future backends.
+	 */
+	if (ConfigFileName)
+		fname = make_absolute_path(ConfigFileName);
+	else if (configdir)
+	{
+		fname = guc_malloc(FATAL,
+						   strlen(configdir) + strlen(CONFIG_FILENAME) + 2);
+		sprintf(fname, "%s/%s", configdir, CONFIG_FILENAME);
+	}
+	else
+	{
+		write_stderr("%s does not know where to find the server configuration file.\n"
+					 "You must specify the --config-file or -D invocation "
+					 "option or set the PGDATA environment variable.\n",
+					 progname);
+		return false;
+	}
+
+	/*
+	 * Set the ConfigFileName GUC variable to its final value, ensuring that
+	 * it can't be overridden later.
+	 */
+	SetConfigOption("config_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
+	free(fname);
+
+	/*
+	 * Now read the config file for the first time.
+	 */
+	if (stat(ConfigFileName, &stat_buf) != 0)
+	{
+		write_stderr("%s: could not access the server configuration file \"%s\": %s\n",
+					 progname, ConfigFileName, strerror(errno));
+		free(configdir);
+		return false;
+	}
+
+	/*
+	 * Read the configuration file for the first time.  This time only the
+	 * data_directory parameter is picked up to determine the data directory,
+	 * so that we can read the PG_AUTOCONF_FILENAME file next time.
+	 */
+	ProcessConfigFile(PGC_POSTMASTER);
+
+	/*
+	 * If the data_directory GUC variable has been set, use that as DataDir;
+	 * otherwise use configdir if set; else punt.
+	 *
+	 * Note: SetDataDir will copy and absolute-ize its argument, so we don't
+	 * have to.
+	 */
+	if (data_directory)
+		SetDataDir(data_directory);
+	else if (configdir)
+		SetDataDir(configdir);
+	else
+	{
+		write_stderr("%s does not know where to find the database system data.\n"
+					 "This can be specified as \"data_directory\" in \"%s\", "
+					 "or by the -D invocation option, or by the "
+					 "PGDATA environment variable.\n",
+					 progname, ConfigFileName);
+		return false;
+	}
+
+	/*
+	 * Reflect the final DataDir value back into the data_directory GUC var.
+	 * (If you are wondering why we don't just make them a single variable,
+	 * it's because the EXEC_BACKEND case needs DataDir to be transmitted to
+	 * child backends specially.  XXX is that still true?  Given that we now
+	 * chdir to DataDir, EXEC_BACKEND can read the config file without knowing
+	 * DataDir in advance.)
+	 */
+	SetConfigOption("data_directory", DataDir, PGC_POSTMASTER, PGC_S_OVERRIDE);
+
+	/*
+	 * Now read the config file a second time, allowing any settings in the
+	 * PG_AUTOCONF_FILENAME file to take effect.  (This is pretty ugly, but
+	 * since we have to determine the DataDir before we can find the autoconf
+	 * file, the alternatives seem worse.)
+	 */
+	ProcessConfigFile(PGC_POSTMASTER);
+
+	/*
+	 * If timezone_abbreviations wasn't set in the configuration file, install
+	 * the default value.  We do it this way because we can't safely install a
+	 * "real" value until my_exec_path is set, which may not have happened
+	 * when InitializeGUCOptions runs, so the bootstrap default value cannot
+	 * be the real desired default.
+	 */
+	pg_timezone_abbrev_initialize();
+
+	/*
+	 * Figure out where pg_hba.conf is, and make sure the path is absolute.
+	 */
+	if (HbaFileName)
+		fname = make_absolute_path(HbaFileName);
+	else if (configdir)
+	{
+		fname = guc_malloc(FATAL,
+						   strlen(configdir) + strlen(HBA_FILENAME) + 2);
+		sprintf(fname, "%s/%s", configdir, HBA_FILENAME);
+	}
+	else
+	{
+		write_stderr("%s does not know where to find the \"hba\" configuration file.\n"
+					 "This can be specified as \"hba_file\" in \"%s\", "
+					 "or by the -D invocation option, or by the "
+					 "PGDATA environment variable.\n",
+					 progname, ConfigFileName);
+		return false;
+	}
+	SetConfigOption("hba_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
+	free(fname);
+
+	/*
+	 * Likewise for pg_ident.conf.
+	 */
+	if (IdentFileName)
+		fname = make_absolute_path(IdentFileName);
+	else if (configdir)
+	{
+		fname = guc_malloc(FATAL,
+						   strlen(configdir) + strlen(IDENT_FILENAME) + 2);
+		sprintf(fname, "%s/%s", configdir, IDENT_FILENAME);
+	}
+	else
+	{
+		write_stderr("%s does not know where to find the \"ident\" configuration file.\n"
+					 "This can be specified as \"ident_file\" in \"%s\", "
+					 "or by the -D invocation option, or by the "
+					 "PGDATA environment variable.\n",
+					 progname, ConfigFileName);
+		return false;
+	}
+	SetConfigOption("ident_file", fname, PGC_POSTMASTER, PGC_S_OVERRIDE);
+	free(fname);
+
+	free(configdir);
+
+	return true;
+}
+
+
+/*
+ * Reset all options to their saved default values (implements RESET ALL)
+ */
+void
+ResetAllOptions(void)
+{
+	int			i;
+
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		/* Don't reset non-SET-able values */
+		if (gconf->context != PGC_SUSET &&
+			gconf->context != PGC_USERSET)
+			continue;
+		/* Don't reset if special exclusion from RESET ALL */
+		if (gconf->flags & GUC_NO_RESET_ALL)
+			continue;
+		/* No need to reset if wasn't SET */
+		if (gconf->source <= PGC_S_OVERRIDE)
+			continue;
+
+		/* Save old value to support transaction abort */
+		push_old_value(gconf, GUC_ACTION_SET);
+
+		switch (gconf->vartype)
+		{
+			case PGC_BOOL:
+				{
+					struct config_bool *conf = (struct config_bool *) gconf;
+
+					if (conf->assign_hook)
+						conf->assign_hook(conf->reset_val,
+										  conf->reset_extra);
+					*conf->variable = conf->reset_val;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									conf->reset_extra);
+					break;
+				}
+			case PGC_INT:
+				{
+					struct config_int *conf = (struct config_int *) gconf;
+
+					if (conf->assign_hook)
+						conf->assign_hook(conf->reset_val,
+										  conf->reset_extra);
+					*conf->variable = conf->reset_val;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									conf->reset_extra);
+					break;
+				}
+			case PGC_REAL:
+				{
+					struct config_real *conf = (struct config_real *) gconf;
+
+					if (conf->assign_hook)
+						conf->assign_hook(conf->reset_val,
+										  conf->reset_extra);
+					*conf->variable = conf->reset_val;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									conf->reset_extra);
+					break;
+				}
+			case PGC_STRING:
+				{
+					struct config_string *conf = (struct config_string *) gconf;
+
+					if (conf->assign_hook)
+						conf->assign_hook(conf->reset_val,
+										  conf->reset_extra);
+					set_string_field(conf, conf->variable, conf->reset_val);
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									conf->reset_extra);
+					break;
+				}
+			case PGC_ENUM:
+				{
+					struct config_enum *conf = (struct config_enum *) gconf;
+
+					if (conf->assign_hook)
+						conf->assign_hook(conf->reset_val,
+										  conf->reset_extra);
+					*conf->variable = conf->reset_val;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									conf->reset_extra);
+					break;
+				}
+		}
+
+		gconf->source = gconf->reset_source;
+		gconf->scontext = gconf->reset_scontext;
+
+		if (gconf->flags & GUC_REPORT)
+		{
+			gconf->status |= GUC_NEEDS_REPORT;
+			report_needed = true;
+		}
+	}
+}
+
+
+/*
+ * push_old_value
+ *		Push previous state during transactional assignment to a GUC variable.
+ */
+static void
+push_old_value(struct config_generic *gconf, GucAction action)
+{
+	GucStack   *stack;
+
+	/* If we're not inside a nest level, do nothing */
+	if (GUCNestLevel == 0)
+		return;
+
+	/* Do we already have a stack entry of the current nest level? */
+	stack = gconf->stack;
+	if (stack && stack->nest_level >= GUCNestLevel)
+	{
+		/* Yes, so adjust its state if necessary */
+		Assert(stack->nest_level == GUCNestLevel);
+		switch (action)
+		{
+			case GUC_ACTION_SET:
+				/* SET overrides any prior action at same nest level */
+				if (stack->state == GUC_SET_LOCAL)
+				{
+					/* must discard old masked value */
+					discard_stack_value(gconf, &stack->masked);
+				}
+				stack->state = GUC_SET;
+				break;
+			case GUC_ACTION_LOCAL:
+				if (stack->state == GUC_SET)
+				{
+					/* SET followed by SET LOCAL, remember SET's value */
+					stack->masked_scontext = gconf->scontext;
+					set_stack_value(gconf, &stack->masked);
+					stack->state = GUC_SET_LOCAL;
+				}
+				/* in all other cases, no change to stack entry */
+				break;
+			case GUC_ACTION_SAVE:
+				/* Could only have a prior SAVE of same variable */
+				Assert(stack->state == GUC_SAVE);
+				break;
+		}
+		Assert(guc_dirty);		/* must be set already */
+		return;
+	}
+
+	/*
+	 * Push a new stack entry
+	 *
+	 * We keep all the stack entries in TopTransactionContext for simplicity.
+	 */
+	stack = (GucStack *) MemoryContextAllocZero(TopTransactionContext,
+												sizeof(GucStack));
+
+	stack->prev = gconf->stack;
+	stack->nest_level = GUCNestLevel;
+	switch (action)
+	{
+		case GUC_ACTION_SET:
+			stack->state = GUC_SET;
+			break;
+		case GUC_ACTION_LOCAL:
+			stack->state = GUC_LOCAL;
+			break;
+		case GUC_ACTION_SAVE:
+			stack->state = GUC_SAVE;
+			break;
+	}
+	stack->source = gconf->source;
+	stack->scontext = gconf->scontext;
+	set_stack_value(gconf, &stack->prior);
+
+	gconf->stack = stack;
+
+	/* Ensure we remember to pop at end of xact */
+	guc_dirty = true;
+}
+
+
+/*
+ * Do GUC processing at main transaction start.
+ */
+void
+AtStart_GUC(void)
+{
+	/*
+	 * The nest level should be 0 between transactions; if it isn't, somebody
+	 * didn't call AtEOXact_GUC, or called it with the wrong nestLevel.  We
+	 * throw a warning but make no other effort to clean up.
+	 */
+	if (GUCNestLevel != 0)
+		elog(WARNING, "GUC nest level = %d at transaction start",
+			 GUCNestLevel);
+	GUCNestLevel = 1;
+}
+
+/*
+ * Enter a new nesting level for GUC values.  This is called at subtransaction
+ * start, and when entering a function that has proconfig settings, and in
+ * some other places where we want to set GUC variables transiently.
+ * NOTE we must not risk error here, else subtransaction start will be unhappy.
+ */
+int
+NewGUCNestLevel(void)
+{
+	return ++GUCNestLevel;
+}
+
+/*
+ * Do GUC processing at transaction or subtransaction commit or abort, or
+ * when exiting a function that has proconfig settings, or when undoing a
+ * transient assignment to some GUC variables.  (The name is thus a bit of
+ * a misnomer; perhaps it should be ExitGUCNestLevel or some such.)
+ * During abort, we discard all GUC settings that were applied at nesting
+ * levels >= nestLevel.  nestLevel == 1 corresponds to the main transaction.
+ */
+void
+AtEOXact_GUC(bool isCommit, int nestLevel)
+{
+	bool		still_dirty;
+	int			i;
+
+	/*
+	 * Note: it's possible to get here with GUCNestLevel == nestLevel-1 during
+	 * abort, if there is a failure during transaction start before
+	 * AtStart_GUC is called.
+	 */
+	Assert(nestLevel > 0 &&
+		   (nestLevel <= GUCNestLevel ||
+			(nestLevel == GUCNestLevel + 1 && !isCommit)));
+
+	/* Quick exit if nothing's changed in this transaction */
+	if (!guc_dirty)
+	{
+		GUCNestLevel = nestLevel - 1;
+		return;
+	}
+
+	still_dirty = false;
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		/*
+		 * Process and pop each stack entry within the nest level. To simplify
+		 * fmgr_security_definer() and other places that use GUC_ACTION_SAVE,
+		 * we allow failure exit from code that uses a local nest level to be
+		 * recovered at the surrounding transaction or subtransaction abort;
+		 * so there could be more than one stack entry to pop.
+		 */
+		while ((stack = gconf->stack) != NULL &&
+			   stack->nest_level >= nestLevel)
+		{
+			GucStack   *prev = stack->prev;
+			bool		restorePrior = false;
+			bool		restoreMasked = false;
+			bool		changed;
+
+			/*
+			 * In this next bit, if we don't set either restorePrior or
+			 * restoreMasked, we must "discard" any unwanted fields of the
+			 * stack entries to avoid leaking memory.  If we do set one of
+			 * those flags, unused fields will be cleaned up after restoring.
+			 */
+			if (!isCommit)		/* if abort, always restore prior value */
+				restorePrior = true;
+			else if (stack->state == GUC_SAVE)
+				restorePrior = true;
+			else if (stack->nest_level == 1)
+			{
+				/* transaction commit */
+				if (stack->state == GUC_SET_LOCAL)
+					restoreMasked = true;
+				else if (stack->state == GUC_SET)
+				{
+					/* we keep the current active value */
+					discard_stack_value(gconf, &stack->prior);
+				}
+				else			/* must be GUC_LOCAL */
+					restorePrior = true;
+			}
+			else if (prev == NULL ||
+					 prev->nest_level < stack->nest_level - 1)
+			{
+				/* decrement entry's level and do not pop it */
+				stack->nest_level--;
+				continue;
+			}
+			else
+			{
+				/*
+				 * We have to merge this stack entry into prev. See README for
+				 * discussion of this bit.
+				 */
+				switch (stack->state)
+				{
+					case GUC_SAVE:
+						Assert(false);	/* can't get here */
+						break;
+
+					case GUC_SET:
+						/* next level always becomes SET */
+						discard_stack_value(gconf, &stack->prior);
+						if (prev->state == GUC_SET_LOCAL)
+							discard_stack_value(gconf, &prev->masked);
+						prev->state = GUC_SET;
+						break;
+
+					case GUC_LOCAL:
+						if (prev->state == GUC_SET)
+						{
+							/* LOCAL migrates down */
+							prev->masked_scontext = stack->scontext;
+							prev->masked = stack->prior;
+							prev->state = GUC_SET_LOCAL;
+						}
+						else
+						{
+							/* else just forget this stack level */
+							discard_stack_value(gconf, &stack->prior);
+						}
+						break;
+
+					case GUC_SET_LOCAL:
+						/* prior state at this level no longer wanted */
+						discard_stack_value(gconf, &stack->prior);
+						/* copy down the masked state */
+						prev->masked_scontext = stack->masked_scontext;
+						if (prev->state == GUC_SET_LOCAL)
+							discard_stack_value(gconf, &prev->masked);
+						prev->masked = stack->masked;
+						prev->state = GUC_SET_LOCAL;
+						break;
+				}
+			}
+
+			changed = false;
+
+			if (restorePrior || restoreMasked)
+			{
+				/* Perform appropriate restoration of the stacked value */
+				config_var_value newvalue;
+				GucSource	newsource;
+				GucContext	newscontext;
+
+				if (restoreMasked)
+				{
+					newvalue = stack->masked;
+					newsource = PGC_S_SESSION;
+					newscontext = stack->masked_scontext;
+				}
+				else
+				{
+					newvalue = stack->prior;
+					newsource = stack->source;
+					newscontext = stack->scontext;
+				}
+
+				switch (gconf->vartype)
+				{
+					case PGC_BOOL:
+						{
+							struct config_bool *conf = (struct config_bool *) gconf;
+							bool		newval = newvalue.val.boolval;
+							void	   *newextra = newvalue.extra;
+
+							if (*conf->variable != newval ||
+								conf->gen.extra != newextra)
+							{
+								if (conf->assign_hook)
+									conf->assign_hook(newval, newextra);
+								*conf->variable = newval;
+								set_extra_field(&conf->gen, &conf->gen.extra,
+												newextra);
+								changed = true;
+							}
+							break;
+						}
+					case PGC_INT:
+						{
+							struct config_int *conf = (struct config_int *) gconf;
+							int			newval = newvalue.val.intval;
+							void	   *newextra = newvalue.extra;
+
+							if (*conf->variable != newval ||
+								conf->gen.extra != newextra)
+							{
+								if (conf->assign_hook)
+									conf->assign_hook(newval, newextra);
+								*conf->variable = newval;
+								set_extra_field(&conf->gen, &conf->gen.extra,
+												newextra);
+								changed = true;
+							}
+							break;
+						}
+					case PGC_REAL:
+						{
+							struct config_real *conf = (struct config_real *) gconf;
+							double		newval = newvalue.val.realval;
+							void	   *newextra = newvalue.extra;
+
+							if (*conf->variable != newval ||
+								conf->gen.extra != newextra)
+							{
+								if (conf->assign_hook)
+									conf->assign_hook(newval, newextra);
+								*conf->variable = newval;
+								set_extra_field(&conf->gen, &conf->gen.extra,
+												newextra);
+								changed = true;
+							}
+							break;
+						}
+					case PGC_STRING:
+						{
+							struct config_string *conf = (struct config_string *) gconf;
+							char	   *newval = newvalue.val.stringval;
+							void	   *newextra = newvalue.extra;
+
+							if (*conf->variable != newval ||
+								conf->gen.extra != newextra)
+							{
+								if (conf->assign_hook)
+									conf->assign_hook(newval, newextra);
+								set_string_field(conf, conf->variable, newval);
+								set_extra_field(&conf->gen, &conf->gen.extra,
+												newextra);
+								changed = true;
+							}
+
+							/*
+							 * Release stacked values if not used anymore. We
+							 * could use discard_stack_value() here, but since
+							 * we have type-specific code anyway, might as
+							 * well inline it.
+							 */
+							set_string_field(conf, &stack->prior.val.stringval, NULL);
+							set_string_field(conf, &stack->masked.val.stringval, NULL);
+							break;
+						}
+					case PGC_ENUM:
+						{
+							struct config_enum *conf = (struct config_enum *) gconf;
+							int			newval = newvalue.val.enumval;
+							void	   *newextra = newvalue.extra;
+
+							if (*conf->variable != newval ||
+								conf->gen.extra != newextra)
+							{
+								if (conf->assign_hook)
+									conf->assign_hook(newval, newextra);
+								*conf->variable = newval;
+								set_extra_field(&conf->gen, &conf->gen.extra,
+												newextra);
+								changed = true;
+							}
+							break;
+						}
+				}
+
+				/*
+				 * Release stacked extra values if not used anymore.
+				 */
+				set_extra_field(gconf, &(stack->prior.extra), NULL);
+				set_extra_field(gconf, &(stack->masked.extra), NULL);
+
+				/* And restore source information */
+				gconf->source = newsource;
+				gconf->scontext = newscontext;
+			}
+
+			/* Finish popping the state stack */
+			gconf->stack = prev;
+			pfree(stack);
+
+			/* Report new value if we changed it */
+			if (changed && (gconf->flags & GUC_REPORT))
+			{
+				gconf->status |= GUC_NEEDS_REPORT;
+				report_needed = true;
+			}
+		}						/* end of stack-popping loop */
+
+		if (stack != NULL)
+			still_dirty = true;
+	}
+
+	/* If there are no remaining stack entries, we can reset guc_dirty */
+	guc_dirty = still_dirty;
+
+	/* Update nesting level */
+	GUCNestLevel = nestLevel - 1;
+}
+
+
+/*
+ * Start up automatic reporting of changes to variables marked GUC_REPORT.
+ * This is executed at completion of backend startup.
+ */
+void
+BeginReportingGUCOptions(void)
+{
+	int			i;
+
+	/*
+	 * Don't do anything unless talking to an interactive frontend.
+	 */
+	if (whereToSendOutput != DestRemote)
+		return;
+
+	reporting_enabled = true;
+
+	/*
+	 * Hack for in_hot_standby: initialize with the value we're about to send.
+	 * (This could be out of date by the time we actually send it, in which
+	 * case the next ReportChangedGUCOptions call will send a duplicate
+	 * report.)
+	 */
+	in_hot_standby = RecoveryInProgress();
+
+	/* Transmit initial values of interesting variables */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *conf = guc_variables[i];
+
+		if (conf->flags & GUC_REPORT)
+			ReportGUCOption(conf);
+	}
+
+	report_needed = false;
+}
+
+/*
+ * ReportChangedGUCOptions: report recently-changed GUC_REPORT variables
+ *
+ * This is called just before we wait for a new client query.
+ *
+ * By handling things this way, we ensure that a ParameterStatus message
+ * is sent at most once per variable per query, even if the variable
+ * changed multiple times within the query.  That's quite possible when
+ * using features such as function SET clauses.  Function SET clauses
+ * also tend to cause values to change intraquery but eventually revert
+ * to their prevailing values; ReportGUCOption is responsible for avoiding
+ * redundant reports in such cases.
+ */
+void
+ReportChangedGUCOptions(void)
+{
+	/* Quick exit if not (yet) enabled */
+	if (!reporting_enabled)
+		return;
+
+	/*
+	 * Since in_hot_standby isn't actually changed by normal GUC actions, we
+	 * need a hack to check whether a new value needs to be reported to the
+	 * client.  For speed, we rely on the assumption that it can never
+	 * transition from false to true.
+	 */
+	if (in_hot_standby && !RecoveryInProgress())
+	{
+		struct config_generic *record;
+
+		record = find_option("in_hot_standby", false, false, ERROR);
+		Assert(record != NULL);
+		record->status |= GUC_NEEDS_REPORT;
+		report_needed = true;
+		in_hot_standby = false;
+	}
+
+	/* Quick exit if no values have been changed */
+	if (!report_needed)
+		return;
+
+	/* Transmit new values of interesting variables */
+	for (int i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *conf = guc_variables[i];
+
+		if ((conf->flags & GUC_REPORT) && (conf->status & GUC_NEEDS_REPORT))
+			ReportGUCOption(conf);
+	}
+
+	report_needed = false;
+}
+
+/*
+ * ReportGUCOption: if appropriate, transmit option value to frontend
+ *
+ * We need not transmit the value if it's the same as what we last
+ * transmitted.  However, clear the NEEDS_REPORT flag in any case.
+ */
+static void
+ReportGUCOption(struct config_generic *record)
+{
+	char	   *val = _ShowOption(record, false);
+
+	if (record->last_reported == NULL ||
+		strcmp(val, record->last_reported) != 0)
+	{
+		StringInfoData msgbuf;
+
+		pq_beginmessage(&msgbuf, 'S');
+		pq_sendstring(&msgbuf, record->name);
+		pq_sendstring(&msgbuf, val);
+		pq_endmessage(&msgbuf);
+
+		/*
+		 * We need a long-lifespan copy.  If strdup() fails due to OOM, we'll
+		 * set last_reported to NULL and thereby possibly make a duplicate
+		 * report later.
+		 */
+		if (record->last_reported)
+			free(record->last_reported);
+		record->last_reported = strdup(val);
+	}
+
+	pfree(val);
+
+	record->status &= ~GUC_NEEDS_REPORT;
+}
+
+/*
+ * Convert a value from one of the human-friendly units ("kB", "min" etc.)
+ * to the given base unit.  'value' and 'unit' are the input value and unit
+ * to convert from (there can be trailing spaces in the unit string).
+ * The converted value is stored in *base_value.
+ * It's caller's responsibility to round off the converted value as necessary
+ * and check for out-of-range.
+ *
+ * Returns true on success, false if the input unit is not recognized.
+ */
+static bool
+convert_to_base_unit(double value, const char *unit,
+					 int base_unit, double *base_value)
+{
+	char		unitstr[MAX_UNIT_LEN + 1];
+	int			unitlen;
+	const unit_conversion *table;
+	int			i;
+
+	/* extract unit string to compare to table entries */
+	unitlen = 0;
+	while (*unit != '\0' && !isspace((unsigned char) *unit) &&
+		   unitlen < MAX_UNIT_LEN)
+		unitstr[unitlen++] = *(unit++);
+	unitstr[unitlen] = '\0';
+	/* allow whitespace after unit */
+	while (isspace((unsigned char) *unit))
+		unit++;
+	if (*unit != '\0')
+		return false;			/* unit too long, or garbage after it */
+
+	/* now search the appropriate table */
+	if (base_unit & GUC_UNIT_MEMORY)
+		table = memory_unit_conversion_table;
+	else
+		table = time_unit_conversion_table;
+
+	for (i = 0; *table[i].unit; i++)
+	{
+		if (base_unit == table[i].base_unit &&
+			strcmp(unitstr, table[i].unit) == 0)
+		{
+			double		cvalue = value * table[i].multiplier;
+
+			/*
+			 * If the user gave a fractional value such as "30.1GB", round it
+			 * off to the nearest multiple of the next smaller unit, if there
+			 * is one.
+			 */
+			if (*table[i + 1].unit &&
+				base_unit == table[i + 1].base_unit)
+				cvalue = rint(cvalue / table[i + 1].multiplier) *
+					table[i + 1].multiplier;
+
+			*base_value = cvalue;
+			return true;
+		}
+	}
+	return false;
+}
+
+/*
+ * Convert an integer value in some base unit to a human-friendly unit.
+ *
+ * The output unit is chosen so that it's the greatest unit that can represent
+ * the value without loss.  For example, if the base unit is GUC_UNIT_KB, 1024
+ * is converted to 1 MB, but 1025 is represented as 1025 kB.
+ */
+static void
+convert_int_from_base_unit(int64 base_value, int base_unit,
+						   int64 *value, const char **unit)
+{
+	const unit_conversion *table;
+	int			i;
+
+	*unit = NULL;
+
+	if (base_unit & GUC_UNIT_MEMORY)
+		table = memory_unit_conversion_table;
+	else
+		table = time_unit_conversion_table;
+
+	for (i = 0; *table[i].unit; i++)
+	{
+		if (base_unit == table[i].base_unit)
+		{
+			/*
+			 * Accept the first conversion that divides the value evenly.  We
+			 * assume that the conversions for each base unit are ordered from
+			 * greatest unit to the smallest!
+			 */
+			if (table[i].multiplier <= 1.0 ||
+				base_value % (int64) table[i].multiplier == 0)
+			{
+				*value = (int64) rint(base_value / table[i].multiplier);
+				*unit = table[i].unit;
+				break;
+			}
+		}
+	}
+
+	Assert(*unit != NULL);
+}
+
+/*
+ * Convert a floating-point value in some base unit to a human-friendly unit.
+ *
+ * Same as above, except we have to do the math a bit differently, and
+ * there's a possibility that we don't find any exact divisor.
+ */
+static void
+convert_real_from_base_unit(double base_value, int base_unit,
+							double *value, const char **unit)
+{
+	const unit_conversion *table;
+	int			i;
+
+	*unit = NULL;
+
+	if (base_unit & GUC_UNIT_MEMORY)
+		table = memory_unit_conversion_table;
+	else
+		table = time_unit_conversion_table;
+
+	for (i = 0; *table[i].unit; i++)
+	{
+		if (base_unit == table[i].base_unit)
+		{
+			/*
+			 * Accept the first conversion that divides the value evenly; or
+			 * if there is none, use the smallest (last) target unit.
+			 *
+			 * What we actually care about here is whether snprintf with "%g"
+			 * will print the value as an integer, so the obvious test of
+			 * "*value == rint(*value)" is too strict; roundoff error might
+			 * make us choose an unreasonably small unit.  As a compromise,
+			 * accept a divisor that is within 1e-8 of producing an integer.
+			 */
+			*value = base_value / table[i].multiplier;
+			*unit = table[i].unit;
+			if (*value > 0 &&
+				fabs((rint(*value) / *value) - 1.0) <= 1e-8)
+				break;
+		}
+	}
+
+	Assert(*unit != NULL);
+}
+
+/*
+ * Return the name of a GUC's base unit (e.g. "ms") given its flags.
+ * Return NULL if the GUC is unitless.
+ */
+static const char *
+get_config_unit_name(int flags)
+{
+	switch (flags & (GUC_UNIT_MEMORY | GUC_UNIT_TIME))
+	{
+		case 0:
+			return NULL;		/* GUC has no units */
+		case GUC_UNIT_BYTE:
+			return "B";
+		case GUC_UNIT_KB:
+			return "kB";
+		case GUC_UNIT_MB:
+			return "MB";
+		case GUC_UNIT_BLOCKS:
+			{
+				static char bbuf[8];
+
+				/* initialize if first time through */
+				if (bbuf[0] == '\0')
+					snprintf(bbuf, sizeof(bbuf), "%dkB", BLCKSZ / 1024);
+				return bbuf;
+			}
+		case GUC_UNIT_XBLOCKS:
+			{
+				static char xbuf[8];
+
+				/* initialize if first time through */
+				if (xbuf[0] == '\0')
+					snprintf(xbuf, sizeof(xbuf), "%dkB", XLOG_BLCKSZ / 1024);
+				return xbuf;
+			}
+		case GUC_UNIT_MS:
+			return "ms";
+		case GUC_UNIT_S:
+			return "s";
+		case GUC_UNIT_MIN:
+			return "min";
+		default:
+			elog(ERROR, "unrecognized GUC units value: %d",
+				 flags & (GUC_UNIT_MEMORY | GUC_UNIT_TIME));
+			return NULL;
+	}
+}
+
+
+/*
+ * Try to parse value as an integer.  The accepted formats are the
+ * usual decimal, octal, or hexadecimal formats, as well as floating-point
+ * formats (which will be rounded to integer after any units conversion).
+ * Optionally, the value can be followed by a unit name if "flags" indicates
+ * a unit is allowed.
+ *
+ * If the string parses okay, return true, else false.
+ * If okay and result is not NULL, return the value in *result.
+ * If not okay and hintmsg is not NULL, *hintmsg is set to a suitable
+ * HINT message, or NULL if no hint provided.
+ */
+bool
+parse_int(const char *value, int *result, int flags, const char **hintmsg)
+{
+	/*
+	 * We assume here that double is wide enough to represent any integer
+	 * value with adequate precision.
+	 */
+	double		val;
+	char	   *endptr;
+
+	/* To suppress compiler warnings, always set output params */
+	if (result)
+		*result = 0;
+	if (hintmsg)
+		*hintmsg = NULL;
+
+	/*
+	 * Try to parse as an integer (allowing octal or hex input).  If the
+	 * conversion stops at a decimal point or 'e', or overflows, re-parse as
+	 * float.  This should work fine as long as we have no unit names starting
+	 * with 'e'.  If we ever do, the test could be extended to check for a
+	 * sign or digit after 'e', but for now that's unnecessary.
+	 */
+	errno = 0;
+	val = strtol(value, &endptr, 0);
+	if (*endptr == '.' || *endptr == 'e' || *endptr == 'E' ||
+		errno == ERANGE)
+	{
+		errno = 0;
+		val = strtod(value, &endptr);
+	}
+
+	if (endptr == value || errno == ERANGE)
+		return false;			/* no HINT for these cases */
+
+	/* reject NaN (infinities will fail range check below) */
+	if (isnan(val))
+		return false;			/* treat same as syntax error; no HINT */
+
+	/* allow whitespace between number and unit */
+	while (isspace((unsigned char) *endptr))
+		endptr++;
+
+	/* Handle possible unit */
+	if (*endptr != '\0')
+	{
+		if ((flags & GUC_UNIT) == 0)
+			return false;		/* this setting does not accept a unit */
+
+		if (!convert_to_base_unit(val,
+								  endptr, (flags & GUC_UNIT),
+								  &val))
+		{
+			/* invalid unit, or garbage after the unit; set hint and fail. */
+			if (hintmsg)
+			{
+				if (flags & GUC_UNIT_MEMORY)
+					*hintmsg = memory_units_hint;
+				else
+					*hintmsg = time_units_hint;
+			}
+			return false;
+		}
+	}
+
+	/* Round to int, then check for overflow */
+	val = rint(val);
+
+	if (val > INT_MAX || val < INT_MIN)
+	{
+		if (hintmsg)
+			*hintmsg = gettext_noop("Value exceeds integer range.");
+		return false;
+	}
+
+	if (result)
+		*result = (int) val;
+	return true;
+}
+
+/*
+ * Try to parse value as a floating point number in the usual format.
+ * Optionally, the value can be followed by a unit name if "flags" indicates
+ * a unit is allowed.
+ *
+ * If the string parses okay, return true, else false.
+ * If okay and result is not NULL, return the value in *result.
+ * If not okay and hintmsg is not NULL, *hintmsg is set to a suitable
+ * HINT message, or NULL if no hint provided.
+ */
+bool
+parse_real(const char *value, double *result, int flags, const char **hintmsg)
+{
+	double		val;
+	char	   *endptr;
+
+	/* To suppress compiler warnings, always set output params */
+	if (result)
+		*result = 0;
+	if (hintmsg)
+		*hintmsg = NULL;
+
+	errno = 0;
+	val = strtod(value, &endptr);
+
+	if (endptr == value || errno == ERANGE)
+		return false;			/* no HINT for these cases */
+
+	/* reject NaN (infinities will fail range checks later) */
+	if (isnan(val))
+		return false;			/* treat same as syntax error; no HINT */
+
+	/* allow whitespace between number and unit */
+	while (isspace((unsigned char) *endptr))
+		endptr++;
+
+	/* Handle possible unit */
+	if (*endptr != '\0')
+	{
+		if ((flags & GUC_UNIT) == 0)
+			return false;		/* this setting does not accept a unit */
+
+		if (!convert_to_base_unit(val,
+								  endptr, (flags & GUC_UNIT),
+								  &val))
+		{
+			/* invalid unit, or garbage after the unit; set hint and fail. */
+			if (hintmsg)
+			{
+				if (flags & GUC_UNIT_MEMORY)
+					*hintmsg = memory_units_hint;
+				else
+					*hintmsg = time_units_hint;
+			}
+			return false;
+		}
+	}
+
+	if (result)
+		*result = val;
+	return true;
+}
+
+
+/*
+ * Lookup the name for an enum option with the selected value.
+ * Should only ever be called with known-valid values, so throws
+ * an elog(ERROR) if the enum option is not found.
+ *
+ * The returned string is a pointer to static data and not
+ * allocated for modification.
+ */
+const char *
+config_enum_lookup_by_value(struct config_enum *record, int val)
+{
+	const struct config_enum_entry *entry;
+
+	for (entry = record->options; entry && entry->name; entry++)
+	{
+		if (entry->val == val)
+			return entry->name;
+	}
+
+	elog(ERROR, "could not find enum option %d for %s",
+		 val, record->gen.name);
+	return NULL;				/* silence compiler */
+}
+
+
+/*
+ * Lookup the value for an enum option with the selected name
+ * (case-insensitive).
+ * If the enum option is found, sets the retval value and returns
+ * true. If it's not found, return false and retval is set to 0.
+ */
+bool
+config_enum_lookup_by_name(struct config_enum *record, const char *value,
+						   int *retval)
+{
+	const struct config_enum_entry *entry;
+
+	for (entry = record->options; entry && entry->name; entry++)
+	{
+		if (pg_strcasecmp(value, entry->name) == 0)
+		{
+			*retval = entry->val;
+			return true;
+		}
+	}
+
+	*retval = 0;
+	return false;
+}
+
+
+/*
+ * Return a list of all available options for an enum, excluding
+ * hidden ones, separated by the given separator.
+ * If prefix is non-NULL, it is added before the first enum value.
+ * If suffix is non-NULL, it is added to the end of the string.
+ */
+static char *
+config_enum_get_options(struct config_enum *record, const char *prefix,
+						const char *suffix, const char *separator)
+{
+	const struct config_enum_entry *entry;
+	StringInfoData retstr;
+	int			seplen;
+
+	initStringInfo(&retstr);
+	appendStringInfoString(&retstr, prefix);
+
+	seplen = strlen(separator);
+	for (entry = record->options; entry && entry->name; entry++)
+	{
+		if (!entry->hidden)
+		{
+			appendStringInfoString(&retstr, entry->name);
+			appendBinaryStringInfo(&retstr, separator, seplen);
+		}
+	}
+
+	/*
+	 * All the entries may have been hidden, leaving the string empty if no
+	 * prefix was given. This indicates a broken GUC setup, since there is no
+	 * use for an enum without any values, so we just check to make sure we
+	 * don't write to invalid memory instead of actually trying to do
+	 * something smart with it.
+	 */
+	if (retstr.len >= seplen)
+	{
+		/* Replace final separator */
+		retstr.data[retstr.len - seplen] = '\0';
+		retstr.len -= seplen;
+	}
+
+	appendStringInfoString(&retstr, suffix);
+
+	return retstr.data;
+}
+
+/*
+ * Parse and validate a proposed value for the specified configuration
+ * parameter.
+ *
+ * This does built-in checks (such as range limits for an integer parameter)
+ * and also calls any check hook the parameter may have.
+ *
+ * record: GUC variable's info record
+ * name: variable name (should match the record of course)
+ * value: proposed value, as a string
+ * source: identifies source of value (check hooks may need this)
+ * elevel: level to log any error reports at
+ * newval: on success, converted parameter value is returned here
+ * newextra: on success, receives any "extra" data returned by check hook
+ *	(caller must initialize *newextra to NULL)
+ *
+ * Returns true if OK, false if not (or throws error, if elevel >= ERROR)
+ */
+static bool
+parse_and_validate_value(struct config_generic *record,
+						 const char *name, const char *value,
+						 GucSource source, int elevel,
+						 union config_var_val *newval, void **newextra)
+{
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) record;
+
+				if (!parse_bool(value, &newval->boolval))
+				{
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("parameter \"%s\" requires a Boolean value",
+									name)));
+					return false;
+				}
+
+				if (!call_bool_check_hook(conf, &newval->boolval, newextra,
+										  source, elevel))
+					return false;
+			}
+			break;
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) record;
+				const char *hintmsg;
+
+				if (!parse_int(value, &newval->intval,
+							   conf->gen.flags, &hintmsg))
+				{
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": \"%s\"",
+									name, value),
+							 hintmsg ? errhint("%s", _(hintmsg)) : 0));
+					return false;
+				}
+
+				if (newval->intval < conf->min || newval->intval > conf->max)
+				{
+					const char *unit = get_config_unit_name(conf->gen.flags);
+
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("%d%s%s is outside the valid range for parameter \"%s\" (%d .. %d)",
+									newval->intval,
+									unit ? " " : "",
+									unit ? unit : "",
+									name,
+									conf->min, conf->max)));
+					return false;
+				}
+
+				if (!call_int_check_hook(conf, &newval->intval, newextra,
+										 source, elevel))
+					return false;
+			}
+			break;
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) record;
+				const char *hintmsg;
+
+				if (!parse_real(value, &newval->realval,
+								conf->gen.flags, &hintmsg))
+				{
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": \"%s\"",
+									name, value),
+							 hintmsg ? errhint("%s", _(hintmsg)) : 0));
+					return false;
+				}
+
+				if (newval->realval < conf->min || newval->realval > conf->max)
+				{
+					const char *unit = get_config_unit_name(conf->gen.flags);
+
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("%g%s%s is outside the valid range for parameter \"%s\" (%g .. %g)",
+									newval->realval,
+									unit ? " " : "",
+									unit ? unit : "",
+									name,
+									conf->min, conf->max)));
+					return false;
+				}
+
+				if (!call_real_check_hook(conf, &newval->realval, newextra,
+										  source, elevel))
+					return false;
+			}
+			break;
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) record;
+
+				/*
+				 * The value passed by the caller could be transient, so we
+				 * always strdup it.
+				 */
+				newval->stringval = guc_strdup(elevel, value);
+				if (newval->stringval == NULL)
+					return false;
+
+				/*
+				 * The only built-in "parsing" check we have is to apply
+				 * truncation if GUC_IS_NAME.
+				 */
+				if (conf->gen.flags & GUC_IS_NAME)
+					truncate_identifier(newval->stringval,
+										strlen(newval->stringval),
+										true);
+
+				if (!call_string_check_hook(conf, &newval->stringval, newextra,
+											source, elevel))
+				{
+					free(newval->stringval);
+					newval->stringval = NULL;
+					return false;
+				}
+			}
+			break;
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) record;
+
+				if (!config_enum_lookup_by_name(conf, value, &newval->enumval))
+				{
+					char	   *hintmsg;
+
+					hintmsg = config_enum_get_options(conf,
+													  "Available values: ",
+													  ".", ", ");
+
+					ereport(elevel,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": \"%s\"",
+									name, value),
+							 hintmsg ? errhint("%s", _(hintmsg)) : 0));
+
+					if (hintmsg)
+						pfree(hintmsg);
+					return false;
+				}
+
+				if (!call_enum_check_hook(conf, &newval->enumval, newextra,
+										  source, elevel))
+					return false;
+			}
+			break;
+	}
+
+	return true;
+}
+
+
+/*
+ * Sets option `name' to given value.
+ *
+ * The value should be a string, which will be parsed and converted to
+ * the appropriate data type.  The context and source parameters indicate
+ * in which context this function is being called, so that it can apply the
+ * access restrictions properly.
+ *
+ * If value is NULL, set the option to its default value (normally the
+ * reset_val, but if source == PGC_S_DEFAULT we instead use the boot_val).
+ *
+ * action indicates whether to set the value globally in the session, locally
+ * to the current top transaction, or just for the duration of a function call.
+ *
+ * If changeVal is false then don't really set the option but do all
+ * the checks to see if it would work.
+ *
+ * elevel should normally be passed as zero, allowing this function to make
+ * its standard choice of ereport level.  However some callers need to be
+ * able to override that choice; they should pass the ereport level to use.
+ *
+ * is_reload should be true only when called from read_nondefault_variables()
+ * or RestoreGUCState(), where we are trying to load some other process's
+ * GUC settings into a new process.
+ *
+ * Return value:
+ *	+1: the value is valid and was successfully applied.
+ *	0:	the name or value is invalid (but see below).
+ *	-1: the value was not applied because of context, priority, or changeVal.
+ *
+ * If there is an error (non-existing option, invalid value) then an
+ * ereport(ERROR) is thrown *unless* this is called for a source for which
+ * we don't want an ERROR (currently, those are defaults, the config file,
+ * and per-database or per-user settings, as well as callers who specify
+ * a less-than-ERROR elevel).  In those cases we write a suitable error
+ * message via ereport() and return 0.
+ *
+ * See also SetConfigOption for an external interface.
+ */
+int
+set_config_option(const char *name, const char *value,
+				  GucContext context, GucSource source,
+				  GucAction action, bool changeVal, int elevel,
+				  bool is_reload)
+{
+	struct config_generic *record;
+	union config_var_val newval_union;
+	void	   *newextra = NULL;
+	bool		prohibitValueChange = false;
+	bool		makeDefault;
+
+	if (elevel == 0)
+	{
+		if (source == PGC_S_DEFAULT || source == PGC_S_FILE)
+		{
+			/*
+			 * To avoid cluttering the log, only the postmaster bleats loudly
+			 * about problems with the config file.
+			 */
+			elevel = IsUnderPostmaster ? DEBUG3 : LOG;
+		}
+		else if (source == PGC_S_GLOBAL ||
+				 source == PGC_S_DATABASE ||
+				 source == PGC_S_USER ||
+				 source == PGC_S_DATABASE_USER)
+			elevel = WARNING;
+		else
+			elevel = ERROR;
+	}
+
+	/*
+	 * GUC_ACTION_SAVE changes are acceptable during a parallel operation,
+	 * because the current worker will also pop the change.  We're probably
+	 * dealing with a function having a proconfig entry.  Only the function's
+	 * body should observe the change, and peer workers do not share in the
+	 * execution of a function call started by this worker.
+	 *
+	 * Other changes might need to affect other workers, so forbid them.
+	 */
+	if (IsInParallelMode() && changeVal && action != GUC_ACTION_SAVE)
+		ereport(elevel,
+				(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
+				 errmsg("cannot set parameters during a parallel operation")));
+
+	record = find_option(name, true, false, elevel);
+	if (record == NULL)
+		return 0;
+
+	/*
+	 * Check if the option can be set at this time. See guc.h for the precise
+	 * rules.
+	 */
+	switch (record->context)
+	{
+		case PGC_INTERNAL:
+			if (context != PGC_INTERNAL)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						 errmsg("parameter \"%s\" cannot be changed",
+								name)));
+				return 0;
+			}
+			break;
+		case PGC_POSTMASTER:
+			if (context == PGC_SIGHUP)
+			{
+				/*
+				 * We are re-reading a PGC_POSTMASTER variable from
+				 * postgresql.conf.  We can't change the setting, so we should
+				 * give a warning if the DBA tries to change it.  However,
+				 * because of variant formats, canonicalization by check
+				 * hooks, etc, we can't just compare the given string directly
+				 * to what's stored.  Set a flag to check below after we have
+				 * the final storable value.
+				 */
+				prohibitValueChange = true;
+			}
+			else if (context != PGC_POSTMASTER)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+								name)));
+				return 0;
+			}
+			break;
+		case PGC_SIGHUP:
+			if (context != PGC_SIGHUP && context != PGC_POSTMASTER)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						 errmsg("parameter \"%s\" cannot be changed now",
+								name)));
+				return 0;
+			}
+
+			/*
+			 * Hmm, the idea of the SIGHUP context is "ought to be global, but
+			 * can be changed after postmaster start". But there's nothing
+			 * that prevents a crafty administrator from sending SIGHUP
+			 * signals to individual backends only.
+			 */
+			break;
+		case PGC_SU_BACKEND:
+			/* Reject if we're connecting but user is not superuser */
+			if (context == PGC_BACKEND)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+						 errmsg("permission denied to set parameter \"%s\"",
+								name)));
+				return 0;
+			}
+			/* fall through to process the same as PGC_BACKEND */
+			/* FALLTHROUGH */
+		case PGC_BACKEND:
+			if (context == PGC_SIGHUP)
+			{
+				/*
+				 * If a PGC_BACKEND or PGC_SU_BACKEND parameter is changed in
+				 * the config file, we want to accept the new value in the
+				 * postmaster (whence it will propagate to
+				 * subsequently-started backends), but ignore it in existing
+				 * backends.  This is a tad klugy, but necessary because we
+				 * don't re-read the config file during backend start.
+				 *
+				 * In EXEC_BACKEND builds, this works differently: we load all
+				 * non-default settings from the CONFIG_EXEC_PARAMS file
+				 * during backend start.  In that case we must accept
+				 * PGC_SIGHUP settings, so as to have the same value as if
+				 * we'd forked from the postmaster.  This can also happen when
+				 * using RestoreGUCState() within a background worker that
+				 * needs to have the same settings as the user backend that
+				 * started it. is_reload will be true when either situation
+				 * applies.
+				 */
+				if (IsUnderPostmaster && !is_reload)
+					return -1;
+			}
+			else if (context != PGC_POSTMASTER &&
+					 context != PGC_BACKEND &&
+					 context != PGC_SU_BACKEND &&
+					 source != PGC_S_CLIENT)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						 errmsg("parameter \"%s\" cannot be set after connection start",
+								name)));
+				return 0;
+			}
+			break;
+		case PGC_SUSET:
+			if (context == PGC_USERSET || context == PGC_BACKEND)
+			{
+				ereport(elevel,
+						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+						 errmsg("permission denied to set parameter \"%s\"",
+								name)));
+				return 0;
+			}
+			break;
+		case PGC_USERSET:
+			/* always okay */
+			break;
+	}
+
+	/*
+	 * Disallow changing GUC_NOT_WHILE_SEC_REST values if we are inside a
+	 * security restriction context.  We can reject this regardless of the GUC
+	 * context or source, mainly because sources that it might be reasonable
+	 * to override for won't be seen while inside a function.
+	 *
+	 * Note: variables marked GUC_NOT_WHILE_SEC_REST should usually be marked
+	 * GUC_NO_RESET_ALL as well, because ResetAllOptions() doesn't check this.
+	 * An exception might be made if the reset value is assumed to be "safe".
+	 *
+	 * Note: this flag is currently used for "session_authorization" and
+	 * "role".  We need to prohibit changing these inside a local userid
+	 * context because when we exit it, GUC won't be notified, leaving things
+	 * out of sync.  (This could be fixed by forcing a new GUC nesting level,
+	 * but that would change behavior in possibly-undesirable ways.)  Also, we
+	 * prohibit changing these in a security-restricted operation because
+	 * otherwise RESET could be used to regain the session user's privileges.
+	 */
+	if (record->flags & GUC_NOT_WHILE_SEC_REST)
+	{
+		if (InLocalUserIdChange())
+		{
+			/*
+			 * Phrasing of this error message is historical, but it's the most
+			 * common case.
+			 */
+			ereport(elevel,
+					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+					 errmsg("cannot set parameter \"%s\" within security-definer function",
+							name)));
+			return 0;
+		}
+		if (InSecurityRestrictedOperation())
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+					 errmsg("cannot set parameter \"%s\" within security-restricted operation",
+							name)));
+			return 0;
+		}
+	}
+
+	/*
+	 * Should we set reset/stacked values?	(If so, the behavior is not
+	 * transactional.)	This is done either when we get a default value from
+	 * the database's/user's/client's default settings or when we reset a
+	 * value to its default.
+	 */
+	makeDefault = changeVal && (source <= PGC_S_OVERRIDE) &&
+		((value != NULL) || source == PGC_S_DEFAULT);
+
+	/*
+	 * Ignore attempted set if overridden by previously processed setting.
+	 * However, if changeVal is false then plow ahead anyway since we are
+	 * trying to find out if the value is potentially good, not actually use
+	 * it. Also keep going if makeDefault is true, since we may want to set
+	 * the reset/stacked values even if we can't set the variable itself.
+	 */
+	if (record->source > source)
+	{
+		if (changeVal && !makeDefault)
+		{
+			elog(DEBUG3, "\"%s\": setting ignored because previous source is higher priority",
+				 name);
+			return -1;
+		}
+		changeVal = false;
+	}
+
+	/*
+	 * Evaluate value and set variable.
+	 */
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) record;
+
+#define newval (newval_union.boolval)
+
+				if (value)
+				{
+					if (!parse_and_validate_value(record, name, value,
+												  source, elevel,
+												  &newval_union, &newextra))
+						return 0;
+				}
+				else if (source == PGC_S_DEFAULT)
+				{
+					newval = conf->boot_val;
+					if (!call_bool_check_hook(conf, &newval, &newextra,
+											  source, elevel))
+						return 0;
+				}
+				else
+				{
+					newval = conf->reset_val;
+					newextra = conf->reset_extra;
+					source = conf->gen.reset_source;
+					context = conf->gen.reset_scontext;
+				}
+
+				if (prohibitValueChange)
+				{
+					/* Release newextra, unless it's reset_extra */
+					if (newextra && !extra_field_used(&conf->gen, newextra))
+						free(newextra);
+
+					if (*conf->variable != newval)
+					{
+						record->status |= GUC_PENDING_RESTART;
+						ereport(elevel,
+								(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+								 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+										name)));
+						return 0;
+					}
+					record->status &= ~GUC_PENDING_RESTART;
+					return -1;
+				}
+
+				if (changeVal)
+				{
+					/* Save old value to support transaction abort */
+					if (!makeDefault)
+						push_old_value(&conf->gen, action);
+
+					if (conf->assign_hook)
+						conf->assign_hook(newval, newextra);
+					*conf->variable = newval;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									newextra);
+					conf->gen.source = source;
+					conf->gen.scontext = context;
+				}
+				if (makeDefault)
+				{
+					GucStack   *stack;
+
+					if (conf->gen.reset_source <= source)
+					{
+						conf->reset_val = newval;
+						set_extra_field(&conf->gen, &conf->reset_extra,
+										newextra);
+						conf->gen.reset_source = source;
+						conf->gen.reset_scontext = context;
+					}
+					for (stack = conf->gen.stack; stack; stack = stack->prev)
+					{
+						if (stack->source <= source)
+						{
+							stack->prior.val.boolval = newval;
+							set_extra_field(&conf->gen, &stack->prior.extra,
+											newextra);
+							stack->source = source;
+							stack->scontext = context;
+						}
+					}
+				}
+
+				/* Perhaps we didn't install newextra anywhere */
+				if (newextra && !extra_field_used(&conf->gen, newextra))
+					free(newextra);
+				break;
+
+#undef newval
+			}
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) record;
+
+#define newval (newval_union.intval)
+
+				if (value)
+				{
+					if (!parse_and_validate_value(record, name, value,
+												  source, elevel,
+												  &newval_union, &newextra))
+						return 0;
+				}
+				else if (source == PGC_S_DEFAULT)
+				{
+					newval = conf->boot_val;
+					if (!call_int_check_hook(conf, &newval, &newextra,
+											 source, elevel))
+						return 0;
+				}
+				else
+				{
+					newval = conf->reset_val;
+					newextra = conf->reset_extra;
+					source = conf->gen.reset_source;
+					context = conf->gen.reset_scontext;
+				}
+
+				if (prohibitValueChange)
+				{
+					/* Release newextra, unless it's reset_extra */
+					if (newextra && !extra_field_used(&conf->gen, newextra))
+						free(newextra);
+
+					if (*conf->variable != newval)
+					{
+						record->status |= GUC_PENDING_RESTART;
+						ereport(elevel,
+								(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+								 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+										name)));
+						return 0;
+					}
+					record->status &= ~GUC_PENDING_RESTART;
+					return -1;
+				}
+
+				if (changeVal)
+				{
+					/* Save old value to support transaction abort */
+					if (!makeDefault)
+						push_old_value(&conf->gen, action);
+
+					if (conf->assign_hook)
+						conf->assign_hook(newval, newextra);
+					*conf->variable = newval;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									newextra);
+					conf->gen.source = source;
+					conf->gen.scontext = context;
+				}
+				if (makeDefault)
+				{
+					GucStack   *stack;
+
+					if (conf->gen.reset_source <= source)
+					{
+						conf->reset_val = newval;
+						set_extra_field(&conf->gen, &conf->reset_extra,
+										newextra);
+						conf->gen.reset_source = source;
+						conf->gen.reset_scontext = context;
+					}
+					for (stack = conf->gen.stack; stack; stack = stack->prev)
+					{
+						if (stack->source <= source)
+						{
+							stack->prior.val.intval = newval;
+							set_extra_field(&conf->gen, &stack->prior.extra,
+											newextra);
+							stack->source = source;
+							stack->scontext = context;
+						}
+					}
+				}
+
+				/* Perhaps we didn't install newextra anywhere */
+				if (newextra && !extra_field_used(&conf->gen, newextra))
+					free(newextra);
+				break;
+
+#undef newval
+			}
+
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) record;
+
+#define newval (newval_union.realval)
+
+				if (value)
+				{
+					if (!parse_and_validate_value(record, name, value,
+												  source, elevel,
+												  &newval_union, &newextra))
+						return 0;
+				}
+				else if (source == PGC_S_DEFAULT)
+				{
+					newval = conf->boot_val;
+					if (!call_real_check_hook(conf, &newval, &newextra,
+											  source, elevel))
+						return 0;
+				}
+				else
+				{
+					newval = conf->reset_val;
+					newextra = conf->reset_extra;
+					source = conf->gen.reset_source;
+					context = conf->gen.reset_scontext;
+				}
+
+				if (prohibitValueChange)
+				{
+					/* Release newextra, unless it's reset_extra */
+					if (newextra && !extra_field_used(&conf->gen, newextra))
+						free(newextra);
+
+					if (*conf->variable != newval)
+					{
+						record->status |= GUC_PENDING_RESTART;
+						ereport(elevel,
+								(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+								 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+										name)));
+						return 0;
+					}
+					record->status &= ~GUC_PENDING_RESTART;
+					return -1;
+				}
+
+				if (changeVal)
+				{
+					/* Save old value to support transaction abort */
+					if (!makeDefault)
+						push_old_value(&conf->gen, action);
+
+					if (conf->assign_hook)
+						conf->assign_hook(newval, newextra);
+					*conf->variable = newval;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									newextra);
+					conf->gen.source = source;
+					conf->gen.scontext = context;
+				}
+				if (makeDefault)
+				{
+					GucStack   *stack;
+
+					if (conf->gen.reset_source <= source)
+					{
+						conf->reset_val = newval;
+						set_extra_field(&conf->gen, &conf->reset_extra,
+										newextra);
+						conf->gen.reset_source = source;
+						conf->gen.reset_scontext = context;
+					}
+					for (stack = conf->gen.stack; stack; stack = stack->prev)
+					{
+						if (stack->source <= source)
+						{
+							stack->prior.val.realval = newval;
+							set_extra_field(&conf->gen, &stack->prior.extra,
+											newextra);
+							stack->source = source;
+							stack->scontext = context;
+						}
+					}
+				}
+
+				/* Perhaps we didn't install newextra anywhere */
+				if (newextra && !extra_field_used(&conf->gen, newextra))
+					free(newextra);
+				break;
+
+#undef newval
+			}
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) record;
+
+#define newval (newval_union.stringval)
+
+				if (value)
+				{
+					if (!parse_and_validate_value(record, name, value,
+												  source, elevel,
+												  &newval_union, &newextra))
+						return 0;
+				}
+				else if (source == PGC_S_DEFAULT)
+				{
+					/* non-NULL boot_val must always get strdup'd */
+					if (conf->boot_val != NULL)
+					{
+						newval = guc_strdup(elevel, conf->boot_val);
+						if (newval == NULL)
+							return 0;
+					}
+					else
+						newval = NULL;
+
+					if (!call_string_check_hook(conf, &newval, &newextra,
+												source, elevel))
+					{
+						free(newval);
+						return 0;
+					}
+				}
+				else
+				{
+					/*
+					 * strdup not needed, since reset_val is already under
+					 * guc.c's control
+					 */
+					newval = conf->reset_val;
+					newextra = conf->reset_extra;
+					source = conf->gen.reset_source;
+					context = conf->gen.reset_scontext;
+				}
+
+				if (prohibitValueChange)
+				{
+					bool		newval_different;
+
+					/* newval shouldn't be NULL, so we're a bit sloppy here */
+					newval_different = (*conf->variable == NULL ||
+										newval == NULL ||
+										strcmp(*conf->variable, newval) != 0);
+
+					/* Release newval, unless it's reset_val */
+					if (newval && !string_field_used(conf, newval))
+						free(newval);
+					/* Release newextra, unless it's reset_extra */
+					if (newextra && !extra_field_used(&conf->gen, newextra))
+						free(newextra);
+
+					if (newval_different)
+					{
+						record->status |= GUC_PENDING_RESTART;
+						ereport(elevel,
+								(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+								 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+										name)));
+						return 0;
+					}
+					record->status &= ~GUC_PENDING_RESTART;
+					return -1;
+				}
+
+				if (changeVal)
+				{
+					/* Save old value to support transaction abort */
+					if (!makeDefault)
+						push_old_value(&conf->gen, action);
+
+					if (conf->assign_hook)
+						conf->assign_hook(newval, newextra);
+					set_string_field(conf, conf->variable, newval);
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									newextra);
+					conf->gen.source = source;
+					conf->gen.scontext = context;
+				}
+
+				if (makeDefault)
+				{
+					GucStack   *stack;
+
+					if (conf->gen.reset_source <= source)
+					{
+						set_string_field(conf, &conf->reset_val, newval);
+						set_extra_field(&conf->gen, &conf->reset_extra,
+										newextra);
+						conf->gen.reset_source = source;
+						conf->gen.reset_scontext = context;
+					}
+					for (stack = conf->gen.stack; stack; stack = stack->prev)
+					{
+						if (stack->source <= source)
+						{
+							set_string_field(conf, &stack->prior.val.stringval,
+											 newval);
+							set_extra_field(&conf->gen, &stack->prior.extra,
+											newextra);
+							stack->source = source;
+							stack->scontext = context;
+						}
+					}
+				}
+
+				/* Perhaps we didn't install newval anywhere */
+				if (newval && !string_field_used(conf, newval))
+					free(newval);
+				/* Perhaps we didn't install newextra anywhere */
+				if (newextra && !extra_field_used(&conf->gen, newextra))
+					free(newextra);
+				break;
+
+#undef newval
+			}
+
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) record;
+
+#define newval (newval_union.enumval)
+
+				if (value)
+				{
+					if (!parse_and_validate_value(record, name, value,
+												  source, elevel,
+												  &newval_union, &newextra))
+						return 0;
+				}
+				else if (source == PGC_S_DEFAULT)
+				{
+					newval = conf->boot_val;
+					if (!call_enum_check_hook(conf, &newval, &newextra,
+											  source, elevel))
+						return 0;
+				}
+				else
+				{
+					newval = conf->reset_val;
+					newextra = conf->reset_extra;
+					source = conf->gen.reset_source;
+					context = conf->gen.reset_scontext;
+				}
+
+				if (prohibitValueChange)
+				{
+					/* Release newextra, unless it's reset_extra */
+					if (newextra && !extra_field_used(&conf->gen, newextra))
+						free(newextra);
+
+					if (*conf->variable != newval)
+					{
+						record->status |= GUC_PENDING_RESTART;
+						ereport(elevel,
+								(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+								 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+										name)));
+						return 0;
+					}
+					record->status &= ~GUC_PENDING_RESTART;
+					return -1;
+				}
+
+				if (changeVal)
+				{
+					/* Save old value to support transaction abort */
+					if (!makeDefault)
+						push_old_value(&conf->gen, action);
+
+					if (conf->assign_hook)
+						conf->assign_hook(newval, newextra);
+					*conf->variable = newval;
+					set_extra_field(&conf->gen, &conf->gen.extra,
+									newextra);
+					conf->gen.source = source;
+					conf->gen.scontext = context;
+				}
+				if (makeDefault)
+				{
+					GucStack   *stack;
+
+					if (conf->gen.reset_source <= source)
+					{
+						conf->reset_val = newval;
+						set_extra_field(&conf->gen, &conf->reset_extra,
+										newextra);
+						conf->gen.reset_source = source;
+						conf->gen.reset_scontext = context;
+					}
+					for (stack = conf->gen.stack; stack; stack = stack->prev)
+					{
+						if (stack->source <= source)
+						{
+							stack->prior.val.enumval = newval;
+							set_extra_field(&conf->gen, &stack->prior.extra,
+											newextra);
+							stack->source = source;
+							stack->scontext = context;
+						}
+					}
+				}
+
+				/* Perhaps we didn't install newextra anywhere */
+				if (newextra && !extra_field_used(&conf->gen, newextra))
+					free(newextra);
+				break;
+
+#undef newval
+			}
+	}
+
+	if (changeVal && (record->flags & GUC_REPORT))
+	{
+		record->status |= GUC_NEEDS_REPORT;
+		report_needed = true;
+	}
+
+	return changeVal ? 1 : -1;
+}
+
+
+/*
+ * Set the fields for source file and line number the setting came from.
+ */
+static void
+set_config_sourcefile(const char *name, char *sourcefile, int sourceline)
+{
+	struct config_generic *record;
+	int			elevel;
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG3 : LOG;
+
+	record = find_option(name, true, false, elevel);
+	/* should not happen */
+	if (record == NULL)
+		return;
+
+	sourcefile = guc_strdup(elevel, sourcefile);
+	if (record->sourcefile)
+		free(record->sourcefile);
+	record->sourcefile = sourcefile;
+	record->sourceline = sourceline;
+}
+
+/*
+ * Set a config option to the given value.
+ *
+ * See also set_config_option; this is just the wrapper to be called from
+ * outside GUC.  (This function should be used when possible, because its API
+ * is more stable than set_config_option's.)
+ *
+ * Note: there is no support here for setting source file/line, as it
+ * is currently not needed.
+ */
+void
+SetConfigOption(const char *name, const char *value,
+				GucContext context, GucSource source)
+{
+	(void) set_config_option(name, value, context, source,
+							 GUC_ACTION_SET, true, 0, false);
+}
+
+
+
+/*
+ * Fetch the current value of the option `name', as a string.
+ *
+ * If the option doesn't exist, return NULL if missing_ok is true (NOTE that
+ * this cannot be distinguished from a string variable with a NULL value!),
+ * otherwise throw an ereport and don't return.
+ *
+ * If restrict_privileged is true, we also enforce that only superusers and
+ * members of the pg_read_all_settings role can see GUC_SUPERUSER_ONLY
+ * variables.  This should only be passed as true in user-driven calls.
+ *
+ * The string is *not* allocated for modification and is really only
+ * valid until the next call to configuration related functions.
+ */
+const char *
+GetConfigOption(const char *name, bool missing_ok, bool restrict_privileged)
+{
+	struct config_generic *record;
+	static char buffer[256];
+
+	record = find_option(name, false, missing_ok, ERROR);
+	if (record == NULL)
+		return NULL;
+	if (restrict_privileged &&
+		(record->flags & GUC_SUPERUSER_ONLY) &&
+		!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser or a member of pg_read_all_settings to examine \"%s\"",
+						name)));
+
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			return *((struct config_bool *) record)->variable ? "on" : "off";
+
+		case PGC_INT:
+			snprintf(buffer, sizeof(buffer), "%d",
+					 *((struct config_int *) record)->variable);
+			return buffer;
+
+		case PGC_REAL:
+			snprintf(buffer, sizeof(buffer), "%g",
+					 *((struct config_real *) record)->variable);
+			return buffer;
+
+		case PGC_STRING:
+			return *((struct config_string *) record)->variable;
+
+		case PGC_ENUM:
+			return config_enum_lookup_by_value((struct config_enum *) record,
+											   *((struct config_enum *) record)->variable);
+	}
+	return NULL;
+}
+
+/*
+ * Get the RESET value associated with the given option.
+ *
+ * Note: this is not re-entrant, due to use of static result buffer;
+ * not to mention that a string variable could have its reset_val changed.
+ * Beware of assuming the result value is good for very long.
+ */
+const char *
+GetConfigOptionResetString(const char *name)
+{
+	struct config_generic *record;
+	static char buffer[256];
+
+	record = find_option(name, false, false, ERROR);
+	Assert(record != NULL);
+	if ((record->flags & GUC_SUPERUSER_ONLY) &&
+		!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser or a member of pg_read_all_settings to examine \"%s\"",
+						name)));
+
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			return ((struct config_bool *) record)->reset_val ? "on" : "off";
+
+		case PGC_INT:
+			snprintf(buffer, sizeof(buffer), "%d",
+					 ((struct config_int *) record)->reset_val);
+			return buffer;
+
+		case PGC_REAL:
+			snprintf(buffer, sizeof(buffer), "%g",
+					 ((struct config_real *) record)->reset_val);
+			return buffer;
+
+		case PGC_STRING:
+			return ((struct config_string *) record)->reset_val;
+
+		case PGC_ENUM:
+			return config_enum_lookup_by_value((struct config_enum *) record,
+											   ((struct config_enum *) record)->reset_val);
+	}
+	return NULL;
+}
+
+/*
+ * Get the GUC flags associated with the given option.
+ *
+ * If the option doesn't exist, return 0 if missing_ok is true,
+ * otherwise throw an ereport and don't return.
+ */
+int
+GetConfigOptionFlags(const char *name, bool missing_ok)
+{
+	struct config_generic *record;
+
+	record = find_option(name, false, missing_ok, ERROR);
+	if (record == NULL)
+		return 0;
+	return record->flags;
+}
+
+
+/*
+ * flatten_set_variable_args
+ *		Given a parsenode List as emitted by the grammar for SET,
+ *		convert to the flat string representation used by GUC.
+ *
+ * We need to be told the name of the variable the args are for, because
+ * the flattening rules vary (ugh).
+ *
+ * The result is NULL if args is NIL (i.e., SET ... TO DEFAULT), otherwise
+ * a palloc'd string.
+ */
+static char *
+flatten_set_variable_args(const char *name, List *args)
+{
+	struct config_generic *record;
+	int			flags;
+	StringInfoData buf;
+	ListCell   *l;
+
+	/* Fast path if just DEFAULT */
+	if (args == NIL)
+		return NULL;
+
+	/*
+	 * Get flags for the variable; if it's not known, use default flags.
+	 * (Caller might throw error later, but not our business to do so here.)
+	 */
+	record = find_option(name, false, true, WARNING);
+	if (record)
+		flags = record->flags;
+	else
+		flags = 0;
+
+	/* Complain if list input and non-list variable */
+	if ((flags & GUC_LIST_INPUT) == 0 &&
+		list_length(args) != 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("SET %s takes only one argument", name)));
+
+	initStringInfo(&buf);
+
+	/*
+	 * Each list member may be a plain A_Const node, or an A_Const within a
+	 * TypeCast; the latter case is supported only for ConstInterval arguments
+	 * (for SET TIME ZONE).
+	 */
+	foreach(l, args)
+	{
+		Node	   *arg = (Node *) lfirst(l);
+		char	   *val;
+		TypeName   *typeName = NULL;
+		A_Const    *con;
+
+		if (l != list_head(args))
+			appendStringInfoString(&buf, ", ");
+
+		if (IsA(arg, TypeCast))
+		{
+			TypeCast   *tc = (TypeCast *) arg;
+
+			arg = tc->arg;
+			typeName = tc->typeName;
+		}
+
+		if (!IsA(arg, A_Const))
+			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(arg));
+		con = (A_Const *) arg;
+
+		switch (nodeTag(&con->val))
+		{
+			case T_Integer:
+				appendStringInfo(&buf, "%d", intVal(&con->val));
+				break;
+			case T_Float:
+				/* represented as a string, so just copy it */
+				appendStringInfoString(&buf, strVal(&con->val));
+				break;
+			case T_String:
+				val = strVal(&con->val);
+				if (typeName != NULL)
+				{
+					/*
+					 * Must be a ConstInterval argument for TIME ZONE. Coerce
+					 * to interval and back to normalize the value and account
+					 * for any typmod.
+					 */
+					Oid			typoid;
+					int32		typmod;
+					Datum		interval;
+					char	   *intervalout;
+
+					typenameTypeIdAndMod(NULL, typeName, &typoid, &typmod);
+					Assert(typoid == INTERVALOID);
+
+					interval =
+						DirectFunctionCall3(interval_in,
+											CStringGetDatum(val),
+											ObjectIdGetDatum(InvalidOid),
+											Int32GetDatum(typmod));
+
+					intervalout =
+						DatumGetCString(DirectFunctionCall1(interval_out,
+															interval));
+					appendStringInfo(&buf, "INTERVAL '%s'", intervalout);
+				}
+				else
+				{
+					/*
+					 * Plain string literal or identifier.  For quote mode,
+					 * quote it if it's not a vanilla identifier.
+					 */
+					if (flags & GUC_LIST_QUOTE)
+						appendStringInfoString(&buf, quote_identifier(val));
+					else
+						appendStringInfoString(&buf, val);
+				}
+				break;
+			default:
+				elog(ERROR, "unrecognized node type: %d",
+					 (int) nodeTag(&con->val));
+				break;
+		}
+	}
+
+	return buf.data;
+}
+
+/*
+ * Write updated configuration parameter values into a temporary file.
+ * This function traverses the list of parameters and quotes the string
+ * values before writing them.
+ */
+static void
+write_auto_conf_file(int fd, const char *filename, ConfigVariable *head)
+{
+	StringInfoData buf;
+	ConfigVariable *item;
+
+	initStringInfo(&buf);
+
+	/* Emit file header containing warning comment */
+	appendStringInfoString(&buf, "# Do not edit this file manually!\n");
+	appendStringInfoString(&buf, "# It will be overwritten by the ALTER SYSTEM command.\n");
+
+	errno = 0;
+	if (write(fd, buf.data, buf.len) != buf.len)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not write to file \"%s\": %m", filename)));
+	}
+
+	/* Emit each parameter, properly quoting the value */
+	for (item = head; item != NULL; item = item->next)
+	{
+		char	   *escaped;
+
+		resetStringInfo(&buf);
+
+		appendStringInfoString(&buf, item->name);
+		appendStringInfoString(&buf, " = '");
+
+		escaped = escape_single_quotes_ascii(item->value);
+		if (!escaped)
+			ereport(ERROR,
+					(errcode(ERRCODE_OUT_OF_MEMORY),
+					 errmsg("out of memory")));
+		appendStringInfoString(&buf, escaped);
+		free(escaped);
+
+		appendStringInfoString(&buf, "'\n");
+
+		errno = 0;
+		if (write(fd, buf.data, buf.len) != buf.len)
+		{
+			/* if write didn't set errno, assume problem is no disk space */
+			if (errno == 0)
+				errno = ENOSPC;
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not write to file \"%s\": %m", filename)));
+		}
+	}
+
+	/* fsync before considering the write to be successful */
+	if (pg_fsync(fd) != 0)
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not fsync file \"%s\": %m", filename)));
+
+	pfree(buf.data);
+}
+
+/*
+ * Update the given list of configuration parameters, adding, replacing
+ * or deleting the entry for item "name" (delete if "value" == NULL).
+ */
+static void
+replace_auto_config_value(ConfigVariable **head_p, ConfigVariable **tail_p,
+						  const char *name, const char *value)
+{
+	ConfigVariable *item,
+			   *next,
+			   *prev = NULL;
+
+	/*
+	 * Remove any existing match(es) for "name".  Normally there'd be at most
+	 * one, but if external tools have modified the config file, there could
+	 * be more.
+	 */
+	for (item = *head_p; item != NULL; item = next)
+	{
+		next = item->next;
+		if (guc_name_compare(item->name, name) == 0)
+		{
+			/* found a match, delete it */
+			if (prev)
+				prev->next = next;
+			else
+				*head_p = next;
+			if (next == NULL)
+				*tail_p = prev;
+
+			pfree(item->name);
+			pfree(item->value);
+			pfree(item->filename);
+			pfree(item);
+		}
+		else
+			prev = item;
+	}
+
+	/* Done if we're trying to delete it */
+	if (value == NULL)
+		return;
+
+	/* OK, append a new entry */
+	item = palloc(sizeof *item);
+	item->name = pstrdup(name);
+	item->value = pstrdup(value);
+	item->errmsg = NULL;
+	item->filename = pstrdup("");	/* new item has no location */
+	item->sourceline = 0;
+	item->ignore = false;
+	item->applied = false;
+	item->next = NULL;
+
+	if (*head_p == NULL)
+		*head_p = item;
+	else
+		(*tail_p)->next = item;
+	*tail_p = item;
+}
+
+
+/*
+ * Execute ALTER SYSTEM statement.
+ *
+ * Read the old PG_AUTOCONF_FILENAME file, merge in the new variable value,
+ * and write out an updated file.  If the command is ALTER SYSTEM RESET ALL,
+ * we can skip reading the old file and just write an empty file.
+ *
+ * An LWLock is used to serialize updates of the configuration file.
+ *
+ * In case of an error, we leave the original automatic
+ * configuration file (PG_AUTOCONF_FILENAME) intact.
+ */
+void
+AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
+{
+	char	   *name;
+	char	   *value;
+	bool		resetall = false;
+	ConfigVariable *head = NULL;
+	ConfigVariable *tail = NULL;
+	volatile int Tmpfd;
+	char		AutoConfFileName[MAXPGPATH];
+	char		AutoConfTmpFileName[MAXPGPATH];
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to execute ALTER SYSTEM command")));
+
+	/*
+	 * Extract statement arguments
+	 */
+	name = altersysstmt->setstmt->name;
+
+	switch (altersysstmt->setstmt->kind)
+	{
+		case VAR_SET_VALUE:
+			value = ExtractSetVariableArgs(altersysstmt->setstmt);
+			break;
+
+		case VAR_SET_DEFAULT:
+		case VAR_RESET:
+			value = NULL;
+			break;
+
+		case VAR_RESET_ALL:
+			value = NULL;
+			resetall = true;
+			break;
+
+		default:
+			elog(ERROR, "unrecognized alter system stmt type: %d",
+				 altersysstmt->setstmt->kind);
+			break;
+	}
+
+	/*
+	 * Unless it's RESET_ALL, validate the target variable and value
+	 */
+	if (!resetall)
+	{
+		struct config_generic *record;
+
+		record = find_option(name, false, false, ERROR);
+		Assert(record != NULL);
+
+		/*
+		 * Don't allow parameters that can't be set in configuration files to
+		 * be set in PG_AUTOCONF_FILENAME file.
+		 */
+		if ((record->context == PGC_INTERNAL) ||
+			(record->flags & GUC_DISALLOW_IN_FILE) ||
+			(record->flags & GUC_DISALLOW_IN_AUTO_FILE))
+			ereport(ERROR,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed",
+							name)));
+
+		/*
+		 * If a value is specified, verify that it's sane.
+		 */
+		if (value)
+		{
+			union config_var_val newval;
+			void	   *newextra = NULL;
+
+			/* Check that it's acceptable for the indicated parameter */
+			if (!parse_and_validate_value(record, name, value,
+										  PGC_S_FILE, ERROR,
+										  &newval, &newextra))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("invalid value for parameter \"%s\": \"%s\"",
+								name, value)));
+
+			if (record->vartype == PGC_STRING && newval.stringval != NULL)
+				free(newval.stringval);
+			if (newextra)
+				free(newextra);
+
+			/*
+			 * We must also reject values containing newlines, because the
+			 * grammar for config files doesn't support embedded newlines in
+			 * string literals.
+			 */
+			if (strchr(value, '\n'))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("parameter value for ALTER SYSTEM must not contain a newline")));
+		}
+	}
+
+	/*
+	 * PG_AUTOCONF_FILENAME and its corresponding temporary file are always in
+	 * the data directory, so we can reference them by simple relative paths.
+	 */
+	snprintf(AutoConfFileName, sizeof(AutoConfFileName), "%s",
+			 PG_AUTOCONF_FILENAME);
+	snprintf(AutoConfTmpFileName, sizeof(AutoConfTmpFileName), "%s.%s",
+			 AutoConfFileName,
+			 "tmp");
+
+	/*
+	 * Only one backend is allowed to operate on PG_AUTOCONF_FILENAME at a
+	 * time.  Use AutoFileLock to ensure that.  We must hold the lock while
+	 * reading the old file contents.
+	 */
+	LWLockAcquire(AutoFileLock, LW_EXCLUSIVE);
+
+	/*
+	 * If we're going to reset everything, then no need to open or parse the
+	 * old file.  We'll just write out an empty list.
+	 */
+	if (!resetall)
+	{
+		struct stat st;
+
+		if (stat(AutoConfFileName, &st) == 0)
+		{
+			/* open old file PG_AUTOCONF_FILENAME */
+			FILE	   *infile;
+
+			infile = AllocateFile(AutoConfFileName, "r");
+			if (infile == NULL)
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not open file \"%s\": %m",
+								AutoConfFileName)));
+
+			/* parse it */
+			if (!ParseConfigFp(infile, AutoConfFileName, 0, LOG, &head, &tail))
+				ereport(ERROR,
+						(errcode(ERRCODE_CONFIG_FILE_ERROR),
+						 errmsg("could not parse contents of file \"%s\"",
+								AutoConfFileName)));
+
+			FreeFile(infile);
+		}
+
+		/*
+		 * Now, replace any existing entry with the new value, or add it if
+		 * not present.
+		 */
+		replace_auto_config_value(&head, &tail, name, value);
+	}
+
+	/*
+	 * To ensure crash safety, first write the new file data to a temp file,
+	 * then atomically rename it into place.
+	 *
+	 * If there is a temp file left over due to a previous crash, it's okay to
+	 * truncate and reuse it.
+	 */
+	Tmpfd = BasicOpenFile(AutoConfTmpFileName,
+						  O_CREAT | O_RDWR | O_TRUNC);
+	if (Tmpfd < 0)
+		ereport(ERROR,
+				(errcode_for_file_access(),
+				 errmsg("could not open file \"%s\": %m",
+						AutoConfTmpFileName)));
+
+	/*
+	 * Use a TRY block to clean up the file if we fail.  Since we need a TRY
+	 * block anyway, OK to use BasicOpenFile rather than OpenTransientFile.
+	 */
+	PG_TRY();
+	{
+		/* Write and sync the new contents to the temporary file */
+		write_auto_conf_file(Tmpfd, AutoConfTmpFileName, head);
+
+		/* Close before renaming; may be required on some platforms */
+		close(Tmpfd);
+		Tmpfd = -1;
+
+		/*
+		 * As the rename is atomic operation, if any problem occurs after this
+		 * at worst it can lose the parameters set by last ALTER SYSTEM
+		 * command.
+		 */
+		durable_rename(AutoConfTmpFileName, AutoConfFileName, ERROR);
+	}
+	PG_CATCH();
+	{
+		/* Close file first, else unlink might fail on some platforms */
+		if (Tmpfd >= 0)
+			close(Tmpfd);
+
+		/* Unlink, but ignore any error */
+		(void) unlink(AutoConfTmpFileName);
+
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+
+	FreeConfigVariables(head);
+
+	LWLockRelease(AutoFileLock);
+}
+
+/*
+ * SET command
+ */
+void
+ExecSetVariableStmt(VariableSetStmt *stmt, bool isTopLevel)
+{
+	GucAction	action = stmt->is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET;
+
+	/*
+	 * Workers synchronize these parameters at the start of the parallel
+	 * operation; then, we block SET during the operation.
+	 */
+	if (IsInParallelMode())
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_STATE),
+				 errmsg("cannot set parameters during a parallel operation")));
+
+	switch (stmt->kind)
+	{
+		case VAR_SET_VALUE:
+		case VAR_SET_CURRENT:
+			if (stmt->is_local)
+				WarnNoTransactionBlock(isTopLevel, "SET LOCAL");
+			(void) set_config_option(stmt->name,
+									 ExtractSetVariableArgs(stmt),
+									 (superuser() ? PGC_SUSET : PGC_USERSET),
+									 PGC_S_SESSION,
+									 action, true, 0, false);
+			break;
+		case VAR_SET_MULTI:
+
+			/*
+			 * Special-case SQL syntaxes.  The TRANSACTION and SESSION
+			 * CHARACTERISTICS cases effectively set more than one variable
+			 * per statement.  TRANSACTION SNAPSHOT only takes one argument,
+			 * but we put it here anyway since it's a special case and not
+			 * related to any GUC variable.
+			 */
+			if (strcmp(stmt->name, "TRANSACTION") == 0)
+			{
+				ListCell   *head;
+
+				WarnNoTransactionBlock(isTopLevel, "SET TRANSACTION");
+
+				foreach(head, stmt->args)
+				{
+					DefElem    *item = (DefElem *) lfirst(head);
+
+					if (strcmp(item->defname, "transaction_isolation") == 0)
+						SetPGVariable("transaction_isolation",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_read_only") == 0)
+						SetPGVariable("transaction_read_only",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_deferrable") == 0)
+						SetPGVariable("transaction_deferrable",
+									  list_make1(item->arg), stmt->is_local);
+					else
+						elog(ERROR, "unexpected SET TRANSACTION element: %s",
+							 item->defname);
+				}
+			}
+			else if (strcmp(stmt->name, "SESSION CHARACTERISTICS") == 0)
+			{
+				ListCell   *head;
+
+				foreach(head, stmt->args)
+				{
+					DefElem    *item = (DefElem *) lfirst(head);
+
+					if (strcmp(item->defname, "transaction_isolation") == 0)
+						SetPGVariable("default_transaction_isolation",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_read_only") == 0)
+						SetPGVariable("default_transaction_read_only",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_deferrable") == 0)
+						SetPGVariable("default_transaction_deferrable",
+									  list_make1(item->arg), stmt->is_local);
+					else
+						elog(ERROR, "unexpected SET SESSION element: %s",
+							 item->defname);
+				}
+			}
+			else if (strcmp(stmt->name, "TRANSACTION SNAPSHOT") == 0)
+			{
+				A_Const    *con = linitial_node(A_Const, stmt->args);
+
+				if (stmt->is_local)
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("SET LOCAL TRANSACTION SNAPSHOT is not implemented")));
+
+				WarnNoTransactionBlock(isTopLevel, "SET TRANSACTION");
+				Assert(nodeTag(&con->val) == T_String);
+				ImportSnapshot(strVal(&con->val));
+			}
+			else
+				elog(ERROR, "unexpected SET MULTI element: %s",
+					 stmt->name);
+			break;
+		case VAR_SET_DEFAULT:
+			if (stmt->is_local)
+				WarnNoTransactionBlock(isTopLevel, "SET LOCAL");
+			/* fall through */
+		case VAR_RESET:
+			if (strcmp(stmt->name, "transaction_isolation") == 0)
+				WarnNoTransactionBlock(isTopLevel, "RESET TRANSACTION");
+
+			(void) set_config_option(stmt->name,
+									 NULL,
+									 (superuser() ? PGC_SUSET : PGC_USERSET),
+									 PGC_S_SESSION,
+									 action, true, 0, false);
+			break;
+		case VAR_RESET_ALL:
+			ResetAllOptions();
+			break;
+	}
+}
+
+/*
+ * Get the value to assign for a VariableSetStmt, or NULL if it's RESET.
+ * The result is palloc'd.
+ *
+ * This is exported for use by actions such as ALTER ROLE SET.
+ */
+char *
+ExtractSetVariableArgs(VariableSetStmt *stmt)
+{
+	switch (stmt->kind)
+	{
+		case VAR_SET_VALUE:
+			return flatten_set_variable_args(stmt->name, stmt->args);
+		case VAR_SET_CURRENT:
+			return GetConfigOptionByName(stmt->name, NULL, false);
+		default:
+			return NULL;
+	}
+}
+
+/*
+ * SetPGVariable - SET command exported as an easily-C-callable function.
+ *
+ * This provides access to SET TO value, as well as SET TO DEFAULT (expressed
+ * by passing args == NIL), but not SET FROM CURRENT functionality.
+ */
+void
+SetPGVariable(const char *name, List *args, bool is_local)
+{
+	char	   *argstring = flatten_set_variable_args(name, args);
+
+	/* Note SET DEFAULT (argstring == NULL) is equivalent to RESET */
+	(void) set_config_option(name,
+							 argstring,
+							 (superuser() ? PGC_SUSET : PGC_USERSET),
+							 PGC_S_SESSION,
+							 is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET,
+							 true, 0, false);
+}
+
+/*
+ * SET command wrapped as a SQL callable function.
+ */
+Datum
+set_config_by_name(PG_FUNCTION_ARGS)
+{
+	char	   *name;
+	char	   *value;
+	char	   *new_value;
+	bool		is_local;
+
+	if (PG_ARGISNULL(0))
+		ereport(ERROR,
+				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+				 errmsg("SET requires parameter name")));
+
+	/* Get the GUC variable name */
+	name = TextDatumGetCString(PG_GETARG_DATUM(0));
+
+	/* Get the desired value or set to NULL for a reset request */
+	if (PG_ARGISNULL(1))
+		value = NULL;
+	else
+		value = TextDatumGetCString(PG_GETARG_DATUM(1));
+
+	/*
+	 * Get the desired state of is_local. Default to false if provided value
+	 * is NULL
+	 */
+	if (PG_ARGISNULL(2))
+		is_local = false;
+	else
+		is_local = PG_GETARG_BOOL(2);
+
+	/* Note SET DEFAULT (argstring == NULL) is equivalent to RESET */
+	(void) set_config_option(name,
+							 value,
+							 (superuser() ? PGC_SUSET : PGC_USERSET),
+							 PGC_S_SESSION,
+							 is_local ? GUC_ACTION_LOCAL : GUC_ACTION_SET,
+							 true, 0, false);
+
+	/* get the new current value */
+	new_value = GetConfigOptionByName(name, NULL, false);
+
+	/* Convert return string to text */
+	PG_RETURN_TEXT_P(cstring_to_text(new_value));
+}
+
+
+/*
+ * Common code for DefineCustomXXXVariable subroutines: allocate the
+ * new variable's config struct and fill in generic fields.
+ */
+static struct config_generic *
+init_custom_variable(const char *name,
+					 const char *short_desc,
+					 const char *long_desc,
+					 GucContext context,
+					 int flags,
+					 enum config_type type,
+					 size_t sz)
+{
+	struct config_generic *gen;
+
+	/*
+	 * Only allow custom PGC_POSTMASTER variables to be created during shared
+	 * library preload; any later than that, we can't ensure that the value
+	 * doesn't change after startup.  This is a fatal elog if it happens; just
+	 * erroring out isn't safe because we don't know what the calling loadable
+	 * module might already have hooked into.
+	 */
+	if (context == PGC_POSTMASTER &&
+		!process_shared_preload_libraries_in_progress)
+		elog(FATAL, "cannot create PGC_POSTMASTER variables after startup");
+
+	/*
+	 * We can't support custom GUC_LIST_QUOTE variables, because the wrong
+	 * things would happen if such a variable were set or pg_dump'd when the
+	 * defining extension isn't loaded.  Again, treat this as fatal because
+	 * the loadable module may be partly initialized already.
+	 */
+	if (flags & GUC_LIST_QUOTE)
+		elog(FATAL, "extensions cannot define GUC_LIST_QUOTE variables");
+
+	/*
+	 * Before pljava commit 398f3b876ed402bdaec8bc804f29e2be95c75139
+	 * (2015-12-15), two of that module's PGC_USERSET variables facilitated
+	 * trivial escalation to superuser privileges.  Restrict the variables to
+	 * protect sites that have yet to upgrade pljava.
+	 */
+	if (context == PGC_USERSET &&
+		(strcmp(name, "pljava.classpath") == 0 ||
+		 strcmp(name, "pljava.vmoptions") == 0))
+		context = PGC_SUSET;
+
+	gen = (struct config_generic *) guc_malloc(ERROR, sz);
+	memset(gen, 0, sz);
+
+	gen->name = guc_strdup(ERROR, name);
+	gen->context = context;
+	gen->group = CUSTOM_OPTIONS;
+	gen->short_desc = short_desc;
+	gen->long_desc = long_desc;
+	gen->flags = flags;
+	gen->vartype = type;
+
+	return gen;
+}
+
+/*
+ * Common code for DefineCustomXXXVariable subroutines: insert the new
+ * variable into the GUC variable array, replacing any placeholder.
+ */
+static void
+define_custom_variable(struct config_generic *variable)
+{
+	const char *name = variable->name;
+	const char **nameAddr = &name;
+	struct config_string *pHolder;
+	struct config_generic **res;
+
+	/*
+	 * See if there's a placeholder by the same name.
+	 */
+	res = (struct config_generic **) bsearch((void *) &nameAddr,
+											 (void *) guc_variables,
+											 num_guc_variables,
+											 sizeof(struct config_generic *),
+											 guc_var_compare);
+	if (res == NULL)
+	{
+		/*
+		 * No placeholder to replace, so we can just add it ... but first,
+		 * make sure it's initialized to its default value.
+		 */
+		InitializeOneGUCOption(variable);
+		add_guc_variable(variable, ERROR);
+		return;
+	}
+
+	/*
+	 * This better be a placeholder
+	 */
+	if (((*res)->flags & GUC_CUSTOM_PLACEHOLDER) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INTERNAL_ERROR),
+				 errmsg("attempt to redefine parameter \"%s\"", name)));
+
+	Assert((*res)->vartype == PGC_STRING);
+	pHolder = (struct config_string *) (*res);
+
+	/*
+	 * First, set the variable to its default value.  We must do this even
+	 * though we intend to immediately apply a new value, since it's possible
+	 * that the new value is invalid.
+	 */
+	InitializeOneGUCOption(variable);
+
+	/*
+	 * Replace the placeholder. We aren't changing the name, so no re-sorting
+	 * is necessary
+	 */
+	*res = variable;
+
+	/*
+	 * Assign the string value(s) stored in the placeholder to the real
+	 * variable.  Essentially, we need to duplicate all the active and stacked
+	 * values, but with appropriate validation and datatype adjustment.
+	 *
+	 * If an assignment fails, we report a WARNING and keep going.  We don't
+	 * want to throw ERROR for bad values, because it'd bollix the add-on
+	 * module that's presumably halfway through getting loaded.  In such cases
+	 * the default or previous state will become active instead.
+	 */
+
+	/* First, apply the reset value if any */
+	if (pHolder->reset_val)
+		(void) set_config_option(name, pHolder->reset_val,
+								 pHolder->gen.reset_scontext,
+								 pHolder->gen.reset_source,
+								 GUC_ACTION_SET, true, WARNING, false);
+	/* That should not have resulted in stacking anything */
+	Assert(variable->stack == NULL);
+
+	/* Now, apply current and stacked values, in the order they were stacked */
+	reapply_stacked_values(variable, pHolder, pHolder->gen.stack,
+						   *(pHolder->variable),
+						   pHolder->gen.scontext, pHolder->gen.source);
+
+	/* Also copy over any saved source-location information */
+	if (pHolder->gen.sourcefile)
+		set_config_sourcefile(name, pHolder->gen.sourcefile,
+							  pHolder->gen.sourceline);
+
+	/*
+	 * Free up as much as we conveniently can of the placeholder structure.
+	 * (This neglects any stack items, so it's possible for some memory to be
+	 * leaked.  Since this can only happen once per session per variable, it
+	 * doesn't seem worth spending much code on.)
+	 */
+	set_string_field(pHolder, pHolder->variable, NULL);
+	set_string_field(pHolder, &pHolder->reset_val, NULL);
+
+	free(pHolder);
+}
+
+/*
+ * Recursive subroutine for define_custom_variable: reapply non-reset values
+ *
+ * We recurse so that the values are applied in the same order as originally.
+ * At each recursion level, apply the upper-level value (passed in) in the
+ * fashion implied by the stack entry.
+ */
+static void
+reapply_stacked_values(struct config_generic *variable,
+					   struct config_string *pHolder,
+					   GucStack *stack,
+					   const char *curvalue,
+					   GucContext curscontext, GucSource cursource)
+{
+	const char *name = variable->name;
+	GucStack   *oldvarstack = variable->stack;
+
+	if (stack != NULL)
+	{
+		/* First, recurse, so that stack items are processed bottom to top */
+		reapply_stacked_values(variable, pHolder, stack->prev,
+							   stack->prior.val.stringval,
+							   stack->scontext, stack->source);
+
+		/* See how to apply the passed-in value */
+		switch (stack->state)
+		{
+			case GUC_SAVE:
+				(void) set_config_option(name, curvalue,
+										 curscontext, cursource,
+										 GUC_ACTION_SAVE, true,
+										 WARNING, false);
+				break;
+
+			case GUC_SET:
+				(void) set_config_option(name, curvalue,
+										 curscontext, cursource,
+										 GUC_ACTION_SET, true,
+										 WARNING, false);
+				break;
+
+			case GUC_LOCAL:
+				(void) set_config_option(name, curvalue,
+										 curscontext, cursource,
+										 GUC_ACTION_LOCAL, true,
+										 WARNING, false);
+				break;
+
+			case GUC_SET_LOCAL:
+				/* first, apply the masked value as SET */
+				(void) set_config_option(name, stack->masked.val.stringval,
+										 stack->masked_scontext, PGC_S_SESSION,
+										 GUC_ACTION_SET, true,
+										 WARNING, false);
+				/* then apply the current value as LOCAL */
+				(void) set_config_option(name, curvalue,
+										 curscontext, cursource,
+										 GUC_ACTION_LOCAL, true,
+										 WARNING, false);
+				break;
+		}
+
+		/* If we successfully made a stack entry, adjust its nest level */
+		if (variable->stack != oldvarstack)
+			variable->stack->nest_level = stack->nest_level;
+	}
+	else
+	{
+		/*
+		 * We are at the end of the stack.  If the active/previous value is
+		 * different from the reset value, it must represent a previously
+		 * committed session value.  Apply it, and then drop the stack entry
+		 * that set_config_option will have created under the impression that
+		 * this is to be just a transactional assignment.  (We leak the stack
+		 * entry.)
+		 */
+		if (curvalue != pHolder->reset_val ||
+			curscontext != pHolder->gen.reset_scontext ||
+			cursource != pHolder->gen.reset_source)
+		{
+			(void) set_config_option(name, curvalue,
+									 curscontext, cursource,
+									 GUC_ACTION_SET, true, WARNING, false);
+			variable->stack = NULL;
+		}
+	}
+}
+
+void
+DefineCustomBoolVariable(const char *name,
+						 const char *short_desc,
+						 const char *long_desc,
+						 bool *valueAddr,
+						 bool bootValue,
+						 GucContext context,
+						 int flags,
+						 GucBoolCheckHook check_hook,
+						 GucBoolAssignHook assign_hook,
+						 GucShowHook show_hook)
+{
+	struct config_bool *var;
+
+	var = (struct config_bool *)
+		init_custom_variable(name, short_desc, long_desc, context, flags,
+							 PGC_BOOL, sizeof(struct config_bool));
+	var->variable = valueAddr;
+	var->boot_val = bootValue;
+	var->reset_val = bootValue;
+	var->check_hook = check_hook;
+	var->assign_hook = assign_hook;
+	var->show_hook = show_hook;
+	define_custom_variable(&var->gen);
+}
+
+void
+DefineCustomIntVariable(const char *name,
+						const char *short_desc,
+						const char *long_desc,
+						int *valueAddr,
+						int bootValue,
+						int minValue,
+						int maxValue,
+						GucContext context,
+						int flags,
+						GucIntCheckHook check_hook,
+						GucIntAssignHook assign_hook,
+						GucShowHook show_hook)
+{
+	struct config_int *var;
+
+	var = (struct config_int *)
+		init_custom_variable(name, short_desc, long_desc, context, flags,
+							 PGC_INT, sizeof(struct config_int));
+	var->variable = valueAddr;
+	var->boot_val = bootValue;
+	var->reset_val = bootValue;
+	var->min = minValue;
+	var->max = maxValue;
+	var->check_hook = check_hook;
+	var->assign_hook = assign_hook;
+	var->show_hook = show_hook;
+	define_custom_variable(&var->gen);
+}
+
+void
+DefineCustomRealVariable(const char *name,
+						 const char *short_desc,
+						 const char *long_desc,
+						 double *valueAddr,
+						 double bootValue,
+						 double minValue,
+						 double maxValue,
+						 GucContext context,
+						 int flags,
+						 GucRealCheckHook check_hook,
+						 GucRealAssignHook assign_hook,
+						 GucShowHook show_hook)
+{
+	struct config_real *var;
+
+	var = (struct config_real *)
+		init_custom_variable(name, short_desc, long_desc, context, flags,
+							 PGC_REAL, sizeof(struct config_real));
+	var->variable = valueAddr;
+	var->boot_val = bootValue;
+	var->reset_val = bootValue;
+	var->min = minValue;
+	var->max = maxValue;
+	var->check_hook = check_hook;
+	var->assign_hook = assign_hook;
+	var->show_hook = show_hook;
+	define_custom_variable(&var->gen);
+}
+
+void
+DefineCustomStringVariable(const char *name,
+						   const char *short_desc,
+						   const char *long_desc,
+						   char **valueAddr,
+						   const char *bootValue,
+						   GucContext context,
+						   int flags,
+						   GucStringCheckHook check_hook,
+						   GucStringAssignHook assign_hook,
+						   GucShowHook show_hook)
+{
+	struct config_string *var;
+
+	var = (struct config_string *)
+		init_custom_variable(name, short_desc, long_desc, context, flags,
+							 PGC_STRING, sizeof(struct config_string));
+	var->variable = valueAddr;
+	var->boot_val = bootValue;
+	var->check_hook = check_hook;
+	var->assign_hook = assign_hook;
+	var->show_hook = show_hook;
+	define_custom_variable(&var->gen);
+}
+
+void
+DefineCustomEnumVariable(const char *name,
+						 const char *short_desc,
+						 const char *long_desc,
+						 int *valueAddr,
+						 int bootValue,
+						 const struct config_enum_entry *options,
+						 GucContext context,
+						 int flags,
+						 GucEnumCheckHook check_hook,
+						 GucEnumAssignHook assign_hook,
+						 GucShowHook show_hook)
+{
+	struct config_enum *var;
+
+	var = (struct config_enum *)
+		init_custom_variable(name, short_desc, long_desc, context, flags,
+							 PGC_ENUM, sizeof(struct config_enum));
+	var->variable = valueAddr;
+	var->boot_val = bootValue;
+	var->reset_val = bootValue;
+	var->options = options;
+	var->check_hook = check_hook;
+	var->assign_hook = assign_hook;
+	var->show_hook = show_hook;
+	define_custom_variable(&var->gen);
+}
+
+void
+EmitWarningsOnPlaceholders(const char *className)
+{
+	int			classLen = strlen(className);
+	int			i;
+
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *var = guc_variables[i];
+
+		if ((var->flags & GUC_CUSTOM_PLACEHOLDER) != 0 &&
+			strncmp(className, var->name, classLen) == 0 &&
+			var->name[classLen] == GUC_QUALIFIER_SEPARATOR)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\"",
+							var->name)));
+		}
+	}
+}
+
+
+/*
+ * SHOW command
+ */
+void
+GetPGVariable(const char *name, DestReceiver *dest)
+{
+	if (guc_name_compare(name, "all") == 0)
+		ShowAllGUCConfig(dest);
+	else
+		ShowGUCConfigOption(name, dest);
+}
+
+TupleDesc
+GetPGVariableResultDesc(const char *name)
+{
+	TupleDesc	tupdesc;
+
+	if (guc_name_compare(name, "all") == 0)
+	{
+		/* need a tuple descriptor representing three TEXT columns */
+		tupdesc = CreateTemplateTupleDesc(3);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "setting",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "description",
+						   TEXTOID, -1, 0);
+	}
+	else
+	{
+		const char *varname;
+
+		/* Get the canonical spelling of name */
+		(void) GetConfigOptionByName(name, &varname, false);
+
+		/* need a tuple descriptor representing a single TEXT column */
+		tupdesc = CreateTemplateTupleDesc(1);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 1, varname,
+						   TEXTOID, -1, 0);
+	}
+	return tupdesc;
+}
+
+
+/*
+ * SHOW command
+ */
+static void
+ShowGUCConfigOption(const char *name, DestReceiver *dest)
+{
+	TupOutputState *tstate;
+	TupleDesc	tupdesc;
+	const char *varname;
+	char	   *value;
+
+	/* Get the value and canonical spelling of name */
+	value = GetConfigOptionByName(name, &varname, false);
+
+	/* need a tuple descriptor representing a single TEXT column */
+	tupdesc = CreateTemplateTupleDesc(1);
+	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, varname,
+							  TEXTOID, -1, 0);
+
+	/* prepare for projection of tuples */
+	tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
+
+	/* Send it */
+	do_text_output_oneline(tstate, value);
+
+	end_tup_output(tstate);
+}
+
+/*
+ * SHOW ALL command
+ */
+static void
+ShowAllGUCConfig(DestReceiver *dest)
+{
+	int			i;
+	TupOutputState *tstate;
+	TupleDesc	tupdesc;
+	Datum		values[3];
+	bool		isnull[3] = {false, false, false};
+
+	/* need a tuple descriptor representing three TEXT columns */
+	tupdesc = CreateTemplateTupleDesc(3);
+	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "name",
+							  TEXTOID, -1, 0);
+	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "setting",
+							  TEXTOID, -1, 0);
+	TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "description",
+							  TEXTOID, -1, 0);
+
+	/* prepare for projection of tuples */
+	tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
+
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *conf = guc_variables[i];
+		char	   *setting;
+
+		if ((conf->flags & GUC_NO_SHOW_ALL) ||
+			((conf->flags & GUC_SUPERUSER_ONLY) &&
+			 !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))
+			continue;
+
+		/* assign to the values array */
+		values[0] = PointerGetDatum(cstring_to_text(conf->name));
+
+		setting = _ShowOption(conf, true);
+		if (setting)
+		{
+			values[1] = PointerGetDatum(cstring_to_text(setting));
+			isnull[1] = false;
+		}
+		else
+		{
+			values[1] = PointerGetDatum(NULL);
+			isnull[1] = true;
+		}
+
+		if (conf->short_desc)
+		{
+			values[2] = PointerGetDatum(cstring_to_text(conf->short_desc));
+			isnull[2] = false;
+		}
+		else
+		{
+			values[2] = PointerGetDatum(NULL);
+			isnull[2] = true;
+		}
+
+		/* send it to dest */
+		do_tup_output(tstate, values, isnull);
+
+		/* clean up */
+		pfree(DatumGetPointer(values[0]));
+		if (setting)
+		{
+			pfree(setting);
+			pfree(DatumGetPointer(values[1]));
+		}
+		if (conf->short_desc)
+			pfree(DatumGetPointer(values[2]));
+	}
+
+	end_tup_output(tstate);
+}
+
+/*
+ * Return an array of modified GUC options to show in EXPLAIN.
+ *
+ * We only report options related to query planning (marked with GUC_EXPLAIN),
+ * with values different from their built-in defaults.
+ */
+struct config_generic **
+get_explain_guc_options(int *num)
+{
+	struct config_generic **result;
+
+	*num = 0;
+
+	/*
+	 * While only a fraction of all the GUC variables are marked GUC_EXPLAIN,
+	 * it doesn't seem worth dynamically resizing this array.
+	 */
+	result = palloc(sizeof(struct config_generic *) * num_guc_variables);
+
+	for (int i = 0; i < num_guc_variables; i++)
+	{
+		bool		modified;
+		struct config_generic *conf = guc_variables[i];
+
+		/* return only parameters marked for inclusion in explain */
+		if (!(conf->flags & GUC_EXPLAIN))
+			continue;
+
+		/* return only options visible to the current user */
+		if ((conf->flags & GUC_NO_SHOW_ALL) ||
+			((conf->flags & GUC_SUPERUSER_ONLY) &&
+			 !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))
+			continue;
+
+		/* return only options that are different from their boot values */
+		modified = false;
+
+		switch (conf->vartype)
+		{
+			case PGC_BOOL:
+				{
+					struct config_bool *lconf = (struct config_bool *) conf;
+
+					modified = (lconf->boot_val != *(lconf->variable));
+				}
+				break;
+
+			case PGC_INT:
+				{
+					struct config_int *lconf = (struct config_int *) conf;
+
+					modified = (lconf->boot_val != *(lconf->variable));
+				}
+				break;
+
+			case PGC_REAL:
+				{
+					struct config_real *lconf = (struct config_real *) conf;
+
+					modified = (lconf->boot_val != *(lconf->variable));
+				}
+				break;
+
+			case PGC_STRING:
+				{
+					struct config_string *lconf = (struct config_string *) conf;
+
+					modified = (strcmp(lconf->boot_val, *(lconf->variable)) != 0);
+				}
+				break;
+
+			case PGC_ENUM:
+				{
+					struct config_enum *lconf = (struct config_enum *) conf;
+
+					modified = (lconf->boot_val != *(lconf->variable));
+				}
+				break;
+
+			default:
+				elog(ERROR, "unexpected GUC type: %d", conf->vartype);
+		}
+
+		if (!modified)
+			continue;
+
+		/* OK, report it */
+		result[*num] = conf;
+		*num = *num + 1;
+	}
+
+	return result;
+}
+
+/*
+ * Return GUC variable value by name; optionally return canonical form of
+ * name.  If the GUC is unset, then throw an error unless missing_ok is true,
+ * in which case return NULL.  Return value is palloc'd (but *varname isn't).
+ */
+char *
+GetConfigOptionByName(const char *name, const char **varname, bool missing_ok)
+{
+	struct config_generic *record;
+
+	record = find_option(name, false, missing_ok, ERROR);
+	if (record == NULL)
+	{
+		if (varname)
+			*varname = NULL;
+		return NULL;
+	}
+
+	if ((record->flags & GUC_SUPERUSER_ONLY) &&
+		!is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser or a member of pg_read_all_settings to examine \"%s\"",
+						name)));
+
+	if (varname)
+		*varname = record->name;
+
+	return _ShowOption(record, true);
+}
+
+/*
+ * Return GUC variable value by variable number; optionally return canonical
+ * form of name.  Return value is palloc'd.
+ */
+void
+GetConfigOptionByNum(int varnum, const char **values, bool *noshow)
+{
+	char		buffer[256];
+	struct config_generic *conf;
+
+	/* check requested variable number valid */
+	Assert((varnum >= 0) && (varnum < num_guc_variables));
+
+	conf = guc_variables[varnum];
+
+	if (noshow)
+	{
+		if ((conf->flags & GUC_NO_SHOW_ALL) ||
+			((conf->flags & GUC_SUPERUSER_ONLY) &&
+			 !is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS)))
+			*noshow = true;
+		else
+			*noshow = false;
+	}
+
+	/* first get the generic attributes */
+
+	/* name */
+	values[0] = conf->name;
+
+	/* setting: use _ShowOption in order to avoid duplicating the logic */
+	values[1] = _ShowOption(conf, false);
+
+	/* unit, if any (NULL is fine) */
+	values[2] = get_config_unit_name(conf->flags);
+
+	/* group */
+	values[3] = _(config_group_names[conf->group]);
+
+	/* short_desc */
+	values[4] = conf->short_desc != NULL ? _(conf->short_desc) : NULL;
+
+	/* extra_desc */
+	values[5] = conf->long_desc != NULL ? _(conf->long_desc) : NULL;
+
+	/* context */
+	values[6] = GucContext_Names[conf->context];
+
+	/* vartype */
+	values[7] = config_type_names[conf->vartype];
+
+	/* source */
+	values[8] = GucSource_Names[conf->source];
+
+	/* now get the type specific attributes */
+	switch (conf->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *lconf = (struct config_bool *) conf;
+
+				/* min_val */
+				values[9] = NULL;
+
+				/* max_val */
+				values[10] = NULL;
+
+				/* enumvals */
+				values[11] = NULL;
+
+				/* boot_val */
+				values[12] = pstrdup(lconf->boot_val ? "on" : "off");
+
+				/* reset_val */
+				values[13] = pstrdup(lconf->reset_val ? "on" : "off");
+			}
+			break;
+
+		case PGC_INT:
+			{
+				struct config_int *lconf = (struct config_int *) conf;
+
+				/* min_val */
+				snprintf(buffer, sizeof(buffer), "%d", lconf->min);
+				values[9] = pstrdup(buffer);
+
+				/* max_val */
+				snprintf(buffer, sizeof(buffer), "%d", lconf->max);
+				values[10] = pstrdup(buffer);
+
+				/* enumvals */
+				values[11] = NULL;
+
+				/* boot_val */
+				snprintf(buffer, sizeof(buffer), "%d", lconf->boot_val);
+				values[12] = pstrdup(buffer);
+
+				/* reset_val */
+				snprintf(buffer, sizeof(buffer), "%d", lconf->reset_val);
+				values[13] = pstrdup(buffer);
+			}
+			break;
+
+		case PGC_REAL:
+			{
+				struct config_real *lconf = (struct config_real *) conf;
+
+				/* min_val */
+				snprintf(buffer, sizeof(buffer), "%g", lconf->min);
+				values[9] = pstrdup(buffer);
+
+				/* max_val */
+				snprintf(buffer, sizeof(buffer), "%g", lconf->max);
+				values[10] = pstrdup(buffer);
+
+				/* enumvals */
+				values[11] = NULL;
+
+				/* boot_val */
+				snprintf(buffer, sizeof(buffer), "%g", lconf->boot_val);
+				values[12] = pstrdup(buffer);
+
+				/* reset_val */
+				snprintf(buffer, sizeof(buffer), "%g", lconf->reset_val);
+				values[13] = pstrdup(buffer);
+			}
+			break;
+
+		case PGC_STRING:
+			{
+				struct config_string *lconf = (struct config_string *) conf;
+
+				/* min_val */
+				values[9] = NULL;
+
+				/* max_val */
+				values[10] = NULL;
+
+				/* enumvals */
+				values[11] = NULL;
+
+				/* boot_val */
+				if (lconf->boot_val == NULL)
+					values[12] = NULL;
+				else
+					values[12] = pstrdup(lconf->boot_val);
+
+				/* reset_val */
+				if (lconf->reset_val == NULL)
+					values[13] = NULL;
+				else
+					values[13] = pstrdup(lconf->reset_val);
+			}
+			break;
+
+		case PGC_ENUM:
+			{
+				struct config_enum *lconf = (struct config_enum *) conf;
+
+				/* min_val */
+				values[9] = NULL;
+
+				/* max_val */
+				values[10] = NULL;
+
+				/* enumvals */
+
+				/*
+				 * NOTE! enumvals with double quotes in them are not
+				 * supported!
+				 */
+				values[11] = config_enum_get_options((struct config_enum *) conf,
+													 "{\"", "\"}", "\",\"");
+
+				/* boot_val */
+				values[12] = pstrdup(config_enum_lookup_by_value(lconf,
+																 lconf->boot_val));
+
+				/* reset_val */
+				values[13] = pstrdup(config_enum_lookup_by_value(lconf,
+																 lconf->reset_val));
+			}
+			break;
+
+		default:
+			{
+				/*
+				 * should never get here, but in case we do, set 'em to NULL
+				 */
+
+				/* min_val */
+				values[9] = NULL;
+
+				/* max_val */
+				values[10] = NULL;
+
+				/* enumvals */
+				values[11] = NULL;
+
+				/* boot_val */
+				values[12] = NULL;
+
+				/* reset_val */
+				values[13] = NULL;
+			}
+			break;
+	}
+
+	/*
+	 * If the setting came from a config file, set the source location. For
+	 * security reasons, we don't show source file/line number for
+	 * insufficiently-privileged users.
+	 */
+	if (conf->source == PGC_S_FILE &&
+		is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_SETTINGS))
+	{
+		values[14] = conf->sourcefile;
+		snprintf(buffer, sizeof(buffer), "%d", conf->sourceline);
+		values[15] = pstrdup(buffer);
+	}
+	else
+	{
+		values[14] = NULL;
+		values[15] = NULL;
+	}
+
+	values[16] = (conf->status & GUC_PENDING_RESTART) ? "t" : "f";
+}
+
+/*
+ * Return the total number of GUC variables
+ */
+int
+GetNumConfigOptions(void)
+{
+	return num_guc_variables;
+}
+
+/*
+ * show_config_by_name - equiv to SHOW X command but implemented as
+ * a function.
+ */
+Datum
+show_config_by_name(PG_FUNCTION_ARGS)
+{
+	char	   *varname = TextDatumGetCString(PG_GETARG_DATUM(0));
+	char	   *varval;
+
+	/* Get the value */
+	varval = GetConfigOptionByName(varname, NULL, false);
+
+	/* Convert to text */
+	PG_RETURN_TEXT_P(cstring_to_text(varval));
+}
+
+/*
+ * show_config_by_name_missing_ok - equiv to SHOW X command but implemented as
+ * a function.  If X does not exist, suppress the error and just return NULL
+ * if missing_ok is true.
+ */
+Datum
+show_config_by_name_missing_ok(PG_FUNCTION_ARGS)
+{
+	char	   *varname = TextDatumGetCString(PG_GETARG_DATUM(0));
+	bool		missing_ok = PG_GETARG_BOOL(1);
+	char	   *varval;
+
+	/* Get the value */
+	varval = GetConfigOptionByName(varname, NULL, missing_ok);
+
+	/* return NULL if no such variable */
+	if (varval == NULL)
+		PG_RETURN_NULL();
+
+	/* Convert to text */
+	PG_RETURN_TEXT_P(cstring_to_text(varval));
+}
+
+/*
+ * show_all_settings - equiv to SHOW ALL command but implemented as
+ * a Table Function.
+ */
+#define NUM_PG_SETTINGS_ATTS	17
+
+Datum
+show_all_settings(PG_FUNCTION_ARGS)
+{
+	FuncCallContext *funcctx;
+	TupleDesc	tupdesc;
+	int			call_cntr;
+	int			max_calls;
+	AttInMetadata *attinmeta;
+	MemoryContext oldcontext;
+
+	/* stuff done only on the first call of the function */
+	if (SRF_IS_FIRSTCALL())
+	{
+		/* create a function context for cross-call persistence */
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		/*
+		 * switch to memory context appropriate for multiple function calls
+		 */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		/*
+		 * need a tuple descriptor representing NUM_PG_SETTINGS_ATTS columns
+		 * of the appropriate types
+		 */
+		tupdesc = CreateTemplateTupleDesc(NUM_PG_SETTINGS_ATTS);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "setting",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "unit",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 4, "category",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 5, "short_desc",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 6, "extra_desc",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 7, "context",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 8, "vartype",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 9, "source",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 10, "min_val",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 11, "max_val",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 12, "enumvals",
+						   TEXTARRAYOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 13, "boot_val",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 14, "reset_val",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 15, "sourcefile",
+						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 16, "sourceline",
+						   INT4OID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 17, "pending_restart",
+						   BOOLOID, -1, 0);
+
+		/*
+		 * Generate attribute metadata needed later to produce tuples from raw
+		 * C strings
+		 */
+		attinmeta = TupleDescGetAttInMetadata(tupdesc);
+		funcctx->attinmeta = attinmeta;
+
+		/* total number of tuples to be returned */
+		funcctx->max_calls = GetNumConfigOptions();
+
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	/* stuff done on every call of the function */
+	funcctx = SRF_PERCALL_SETUP();
+
+	call_cntr = funcctx->call_cntr;
+	max_calls = funcctx->max_calls;
+	attinmeta = funcctx->attinmeta;
+
+	if (call_cntr < max_calls)	/* do when there is more left to send */
+	{
+		char	   *values[NUM_PG_SETTINGS_ATTS];
+		bool		noshow;
+		HeapTuple	tuple;
+		Datum		result;
+
+		/*
+		 * Get the next visible GUC variable name and value
+		 */
+		do
+		{
+			GetConfigOptionByNum(call_cntr, (const char **) values, &noshow);
+			if (noshow)
+			{
+				/* bump the counter and get the next config setting */
+				call_cntr = ++funcctx->call_cntr;
+
+				/* make sure we haven't gone too far now */
+				if (call_cntr >= max_calls)
+					SRF_RETURN_DONE(funcctx);
+			}
+		} while (noshow);
+
+		/* build a tuple */
+		tuple = BuildTupleFromCStrings(attinmeta, values);
+
+		/* make the tuple into a datum */
+		result = HeapTupleGetDatum(tuple);
+
+		SRF_RETURN_NEXT(funcctx, result);
+	}
+	else
+	{
+		/* do when there is no more left */
+		SRF_RETURN_DONE(funcctx);
+	}
+}
+
+/*
+ * show_all_file_settings
+ *
+ * Returns a table of all parameter settings in all configuration files
+ * which includes the config file pathname, the line number, a sequence number
+ * indicating the order in which the settings were encountered, the parameter
+ * name and value, a bool showing if the value could be applied, and possibly
+ * an associated error message.  (For problems such as syntax errors, the
+ * parameter name/value might be NULL.)
+ *
+ * Note: no filtering is done here, instead we depend on the GRANT system
+ * to prevent unprivileged users from accessing this function or the view
+ * built on top of it.
+ */
+Datum
+show_all_file_settings(PG_FUNCTION_ARGS)
+{
+#define NUM_PG_FILE_SETTINGS_ATTS 7
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	TupleDesc	tupdesc;
+	Tuplestorestate *tupstore;
+	ConfigVariable *conf;
+	int			seqno;
+	MemoryContext per_query_ctx;
+	MemoryContext oldcontext;
+
+	/* Check to see if caller supports us returning a tuplestore */
+	if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("set-valued function called in context that cannot accept a set")));
+	if (!(rsinfo->allowedModes & SFRM_Materialize))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("materialize mode required, but it is not allowed in this context")));
+
+	/* Scan the config files using current context as workspace */
+	conf = ProcessConfigFileInternal(PGC_SIGHUP, false, DEBUG3);
+
+	/* Switch into long-lived context to construct returned data structures */
+	per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
+	oldcontext = MemoryContextSwitchTo(per_query_ctx);
+
+	/* Build a tuple descriptor for our result type */
+	tupdesc = CreateTemplateTupleDesc(NUM_PG_FILE_SETTINGS_ATTS);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "sourcefile",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "sourceline",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "seqno",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "name",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "setting",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "applied",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "error",
+					   TEXTOID, -1, 0);
+
+	/* Build a tuplestore to return our results in */
+	tupstore = tuplestore_begin_heap(true, false, work_mem);
+	rsinfo->returnMode = SFRM_Materialize;
+	rsinfo->setResult = tupstore;
+	rsinfo->setDesc = tupdesc;
+
+	/* The rest can be done in short-lived context */
+	MemoryContextSwitchTo(oldcontext);
+
+	/* Process the results and create a tuplestore */
+	for (seqno = 1; conf != NULL; conf = conf->next, seqno++)
+	{
+		Datum		values[NUM_PG_FILE_SETTINGS_ATTS];
+		bool		nulls[NUM_PG_FILE_SETTINGS_ATTS];
+
+		memset(values, 0, sizeof(values));
+		memset(nulls, 0, sizeof(nulls));
+
+		/* sourcefile */
+		if (conf->filename)
+			values[0] = PointerGetDatum(cstring_to_text(conf->filename));
+		else
+			nulls[0] = true;
+
+		/* sourceline (not meaningful if no sourcefile) */
+		if (conf->filename)
+			values[1] = Int32GetDatum(conf->sourceline);
+		else
+			nulls[1] = true;
+
+		/* seqno */
+		values[2] = Int32GetDatum(seqno);
+
+		/* name */
+		if (conf->name)
+			values[3] = PointerGetDatum(cstring_to_text(conf->name));
+		else
+			nulls[3] = true;
+
+		/* setting */
+		if (conf->value)
+			values[4] = PointerGetDatum(cstring_to_text(conf->value));
+		else
+			nulls[4] = true;
+
+		/* applied */
+		values[5] = BoolGetDatum(conf->applied);
+
+		/* error */
+		if (conf->errmsg)
+			values[6] = PointerGetDatum(cstring_to_text(conf->errmsg));
+		else
+			nulls[6] = true;
+
+		/* shove row into tuplestore */
+		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
+	}
+
+	tuplestore_donestoring(tupstore);
+
+	return (Datum) 0;
+}
+
+static char *
+_ShowOption(struct config_generic *record, bool use_units)
+{
+	char		buffer[256];
+	const char *val;
+
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) record;
+
+				if (conf->show_hook)
+					val = conf->show_hook();
+				else
+					val = *conf->variable ? "on" : "off";
+			}
+			break;
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) record;
+
+				if (conf->show_hook)
+					val = conf->show_hook();
+				else
+				{
+					/*
+					 * Use int64 arithmetic to avoid overflows in units
+					 * conversion.
+					 */
+					int64		result = *conf->variable;
+					const char *unit;
+
+					if (use_units && result > 0 && (record->flags & GUC_UNIT))
+						convert_int_from_base_unit(result,
+												   record->flags & GUC_UNIT,
+												   &result, &unit);
+					else
+						unit = "";
+
+					snprintf(buffer, sizeof(buffer), INT64_FORMAT "%s",
+							 result, unit);
+					val = buffer;
+				}
+			}
+			break;
+
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) record;
+
+				if (conf->show_hook)
+					val = conf->show_hook();
+				else
+				{
+					double		result = *conf->variable;
+					const char *unit;
+
+					if (use_units && result > 0 && (record->flags & GUC_UNIT))
+						convert_real_from_base_unit(result,
+													record->flags & GUC_UNIT,
+													&result, &unit);
+					else
+						unit = "";
+
+					snprintf(buffer, sizeof(buffer), "%g%s",
+							 result, unit);
+					val = buffer;
+				}
+			}
+			break;
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) record;
+
+				if (conf->show_hook)
+					val = conf->show_hook();
+				else if (*conf->variable && **conf->variable)
+					val = *conf->variable;
+				else
+					val = "";
+			}
+			break;
+
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) record;
+
+				if (conf->show_hook)
+					val = conf->show_hook();
+				else
+					val = config_enum_lookup_by_value(conf, *conf->variable);
+			}
+			break;
+
+		default:
+			/* just to keep compiler quiet */
+			val = "???";
+			break;
+	}
+
+	return pstrdup(val);
+}
+
+
+#ifdef EXEC_BACKEND
+
+/*
+ *	These routines dump out all non-default GUC options into a binary
+ *	file that is read by all exec'ed backends.  The format is:
+ *
+ *		variable name, string, null terminated
+ *		variable value, string, null terminated
+ *		variable sourcefile, string, null terminated (empty if none)
+ *		variable sourceline, integer
+ *		variable source, integer
+ *		variable scontext, integer
+ */
+static void
+write_one_nondefault_variable(FILE *fp, struct config_generic *gconf)
+{
+	if (gconf->source == PGC_S_DEFAULT)
+		return;
+
+	fprintf(fp, "%s", gconf->name);
+	fputc(0, fp);
+
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) gconf;
+
+				if (*conf->variable)
+					fprintf(fp, "true");
+				else
+					fprintf(fp, "false");
+			}
+			break;
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) gconf;
+
+				fprintf(fp, "%d", *conf->variable);
+			}
+			break;
+
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) gconf;
+
+				fprintf(fp, "%.17g", *conf->variable);
+			}
+			break;
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) gconf;
+
+				fprintf(fp, "%s", *conf->variable);
+			}
+			break;
+
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) gconf;
+
+				fprintf(fp, "%s",
+						config_enum_lookup_by_value(conf, *conf->variable));
+			}
+			break;
+	}
+
+	fputc(0, fp);
+
+	if (gconf->sourcefile)
+		fprintf(fp, "%s", gconf->sourcefile);
+	fputc(0, fp);
+
+	fwrite(&gconf->sourceline, 1, sizeof(gconf->sourceline), fp);
+	fwrite(&gconf->source, 1, sizeof(gconf->source), fp);
+	fwrite(&gconf->scontext, 1, sizeof(gconf->scontext), fp);
+}
+
+void
+write_nondefault_variables(GucContext context)
+{
+	int			elevel;
+	FILE	   *fp;
+	int			i;
+
+	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
+
+	elevel = (context == PGC_SIGHUP) ? LOG : ERROR;
+
+	/*
+	 * Open file
+	 */
+	fp = AllocateFile(CONFIG_EXEC_PARAMS_NEW, "w");
+	if (!fp)
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not write to file \"%s\": %m",
+						CONFIG_EXEC_PARAMS_NEW)));
+		return;
+	}
+
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		write_one_nondefault_variable(fp, guc_variables[i]);
+	}
+
+	if (FreeFile(fp))
+	{
+		ereport(elevel,
+				(errcode_for_file_access(),
+				 errmsg("could not write to file \"%s\": %m",
+						CONFIG_EXEC_PARAMS_NEW)));
+		return;
+	}
+
+	/*
+	 * Put new file in place.  This could delay on Win32, but we don't hold
+	 * any exclusive locks.
+	 */
+	rename(CONFIG_EXEC_PARAMS_NEW, CONFIG_EXEC_PARAMS);
+}
+
+
+/*
+ *	Read string, including null byte from file
+ *
+ *	Return NULL on EOF and nothing read
+ */
+static char *
+read_string_with_null(FILE *fp)
+{
+	int			i = 0,
+				ch,
+				maxlen = 256;
+	char	   *str = NULL;
+
+	do
+	{
+		if ((ch = fgetc(fp)) == EOF)
+		{
+			if (i == 0)
+				return NULL;
+			else
+				elog(FATAL, "invalid format of exec config params file");
+		}
+		if (i == 0)
+			str = guc_malloc(FATAL, maxlen);
+		else if (i == maxlen)
+			str = guc_realloc(FATAL, str, maxlen *= 2);
+		str[i++] = ch;
+	} while (ch != 0);
+
+	return str;
+}
+
+
+/*
+ *	This routine loads a previous postmaster dump of its non-default
+ *	settings.
+ */
+void
+read_nondefault_variables(void)
+{
+	FILE	   *fp;
+	char	   *varname,
+			   *varvalue,
+			   *varsourcefile;
+	int			varsourceline;
+	GucSource	varsource;
+	GucContext	varscontext;
+
+	/*
+	 * Open file
+	 */
+	fp = AllocateFile(CONFIG_EXEC_PARAMS, "r");
+	if (!fp)
+	{
+		/* File not found is fine */
+		if (errno != ENOENT)
+			ereport(FATAL,
+					(errcode_for_file_access(),
+					 errmsg("could not read from file \"%s\": %m",
+							CONFIG_EXEC_PARAMS)));
+		return;
+	}
+
+	for (;;)
+	{
+		struct config_generic *record;
+
+		if ((varname = read_string_with_null(fp)) == NULL)
+			break;
+
+		if ((record = find_option(varname, true, false, FATAL)) == NULL)
+			elog(FATAL, "failed to locate variable \"%s\" in exec config params file", varname);
+
+		if ((varvalue = read_string_with_null(fp)) == NULL)
+			elog(FATAL, "invalid format of exec config params file");
+		if ((varsourcefile = read_string_with_null(fp)) == NULL)
+			elog(FATAL, "invalid format of exec config params file");
+		if (fread(&varsourceline, 1, sizeof(varsourceline), fp) != sizeof(varsourceline))
+			elog(FATAL, "invalid format of exec config params file");
+		if (fread(&varsource, 1, sizeof(varsource), fp) != sizeof(varsource))
+			elog(FATAL, "invalid format of exec config params file");
+		if (fread(&varscontext, 1, sizeof(varscontext), fp) != sizeof(varscontext))
+			elog(FATAL, "invalid format of exec config params file");
+
+		(void) set_config_option(varname, varvalue,
+								 varscontext, varsource,
+								 GUC_ACTION_SET, true, 0, true);
+		if (varsourcefile[0])
+			set_config_sourcefile(varname, varsourcefile, varsourceline);
+
+		free(varname);
+		free(varvalue);
+		free(varsourcefile);
+	}
+
+	FreeFile(fp);
+}
+#endif							/* EXEC_BACKEND */
+
+/*
+ * can_skip_gucvar:
+ * Decide whether SerializeGUCState can skip sending this GUC variable,
+ * or whether RestoreGUCState can skip resetting this GUC to default.
+ *
+ * It is somewhat magical and fragile that the same test works for both cases.
+ * Realize in particular that we are very likely selecting different sets of
+ * GUCs on the leader and worker sides!  Be sure you've understood the
+ * comments here and in RestoreGUCState thoroughly before changing this.
+ */
+static bool
+can_skip_gucvar(struct config_generic *gconf)
+{
+	/*
+	 * We can skip GUCs that are guaranteed to have the same values in leaders
+	 * and workers.  (Note it is critical that the leader and worker have the
+	 * same idea of which GUCs fall into this category.  It's okay to consider
+	 * context and name for this purpose, since those are unchanging
+	 * properties of a GUC.)
+	 *
+	 * PGC_POSTMASTER variables always have the same value in every child of a
+	 * particular postmaster, so the worker will certainly have the right
+	 * value already.  Likewise, PGC_INTERNAL variables are set by special
+	 * mechanisms (if indeed they aren't compile-time constants).  So we may
+	 * always skip these.
+	 *
+	 * Role must be handled specially because its current value can be an
+	 * invalid value (for instance, if someone dropped the role since we set
+	 * it).  So if we tried to serialize it normally, we might get a failure.
+	 * We skip it here, and use another mechanism to ensure the worker has the
+	 * right value.
+	 *
+	 * For all other GUCs, we skip if the GUC has its compiled-in default
+	 * value (i.e., source == PGC_S_DEFAULT).  On the leader side, this means
+	 * we don't send GUCs that have their default values, which typically
+	 * saves lots of work.  On the worker side, this means we don't need to
+	 * reset the GUC to default because it already has that value.  See
+	 * comments in RestoreGUCState for more info.
+	 */
+	return gconf->context == PGC_POSTMASTER ||
+		gconf->context == PGC_INTERNAL || gconf->source == PGC_S_DEFAULT ||
+		strcmp(gconf->name, "role") == 0;
+}
+
+/*
+ * estimate_variable_size:
+ *		Compute space needed for dumping the given GUC variable.
+ *
+ * It's OK to overestimate, but not to underestimate.
+ */
+static Size
+estimate_variable_size(struct config_generic *gconf)
+{
+	Size		size;
+	Size		valsize = 0;
+
+	/* Skippable GUCs consume zero space. */
+	if (can_skip_gucvar(gconf))
+		return 0;
+
+	/* Name, plus trailing zero byte. */
+	size = strlen(gconf->name) + 1;
+
+	/* Get the maximum display length of the GUC value. */
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			{
+				valsize = 5;	/* max(strlen('true'), strlen('false')) */
+			}
+			break;
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) gconf;
+
+				/*
+				 * Instead of getting the exact display length, use max
+				 * length.  Also reduce the max length for typical ranges of
+				 * small values.  Maximum value is 2147483647, i.e. 10 chars.
+				 * Include one byte for sign.
+				 */
+				if (Abs(*conf->variable) < 1000)
+					valsize = 3 + 1;
+				else
+					valsize = 10 + 1;
+			}
+			break;
+
+		case PGC_REAL:
+			{
+				/*
+				 * We are going to print it with %e with REALTYPE_PRECISION
+				 * fractional digits.  Account for sign, leading digit,
+				 * decimal point, and exponent with up to 3 digits.  E.g.
+				 * -3.99329042340000021e+110
+				 */
+				valsize = 1 + 1 + 1 + REALTYPE_PRECISION + 5;
+			}
+			break;
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) gconf;
+
+				/*
+				 * If the value is NULL, we transmit it as an empty string.
+				 * Although this is not physically the same value, GUC
+				 * generally treats a NULL the same as empty string.
+				 */
+				if (*conf->variable)
+					valsize = strlen(*conf->variable);
+				else
+					valsize = 0;
+			}
+			break;
+
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) gconf;
+
+				valsize = strlen(config_enum_lookup_by_value(conf, *conf->variable));
+			}
+			break;
+	}
+
+	/* Allow space for terminating zero-byte for value */
+	size = add_size(size, valsize + 1);
+
+	if (gconf->sourcefile)
+		size = add_size(size, strlen(gconf->sourcefile));
+
+	/* Allow space for terminating zero-byte for sourcefile */
+	size = add_size(size, 1);
+
+	/* Include line whenever file is nonempty. */
+	if (gconf->sourcefile && gconf->sourcefile[0])
+		size = add_size(size, sizeof(gconf->sourceline));
+
+	size = add_size(size, sizeof(gconf->source));
+	size = add_size(size, sizeof(gconf->scontext));
+
+	return size;
+}
+
+/*
+ * EstimateGUCStateSpace:
+ * Returns the size needed to store the GUC state for the current process
+ */
+Size
+EstimateGUCStateSpace(void)
+{
+	Size		size;
+	int			i;
+
+	/* Add space reqd for saving the data size of the guc state */
+	size = sizeof(Size);
+
+	/* Add up the space needed for each GUC variable */
+	for (i = 0; i < num_guc_variables; i++)
+		size = add_size(size,
+						estimate_variable_size(guc_variables[i]));
+
+	return size;
+}
+
+/*
+ * do_serialize:
+ * Copies the formatted string into the destination.  Moves ahead the
+ * destination pointer, and decrements the maxbytes by that many bytes. If
+ * maxbytes is not sufficient to copy the string, error out.
+ */
+static void
+do_serialize(char **destptr, Size *maxbytes, const char *fmt,...)
+{
+	va_list		vargs;
+	int			n;
+
+	if (*maxbytes <= 0)
+		elog(ERROR, "not enough space to serialize GUC state");
+
+	va_start(vargs, fmt);
+	n = vsnprintf(*destptr, *maxbytes, fmt, vargs);
+	va_end(vargs);
+
+	if (n < 0)
+	{
+		/* Shouldn't happen. Better show errno description. */
+		elog(ERROR, "vsnprintf failed: %m with format string \"%s\"", fmt);
+	}
+	if (n >= *maxbytes)
+	{
+		/* This shouldn't happen either, really. */
+		elog(ERROR, "not enough space to serialize GUC state");
+	}
+
+	/* Shift the destptr ahead of the null terminator */
+	*destptr += n + 1;
+	*maxbytes -= n + 1;
+}
+
+/* Binary copy version of do_serialize() */
+static void
+do_serialize_binary(char **destptr, Size *maxbytes, void *val, Size valsize)
+{
+	if (valsize > *maxbytes)
+		elog(ERROR, "not enough space to serialize GUC state");
+
+	memcpy(*destptr, val, valsize);
+	*destptr += valsize;
+	*maxbytes -= valsize;
+}
+
+/*
+ * serialize_variable:
+ * Dumps name, value and other information of a GUC variable into destptr.
+ */
+static void
+serialize_variable(char **destptr, Size *maxbytes,
+				   struct config_generic *gconf)
+{
+	/* Ignore skippable GUCs. */
+	if (can_skip_gucvar(gconf))
+		return;
+
+	do_serialize(destptr, maxbytes, "%s", gconf->name);
+
+	switch (gconf->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) gconf;
+
+				do_serialize(destptr, maxbytes,
+							 (*conf->variable ? "true" : "false"));
+			}
+			break;
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) gconf;
+
+				do_serialize(destptr, maxbytes, "%d", *conf->variable);
+			}
+			break;
+
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) gconf;
+
+				do_serialize(destptr, maxbytes, "%.*e",
+							 REALTYPE_PRECISION, *conf->variable);
+			}
+			break;
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) gconf;
+
+				/* NULL becomes empty string, see estimate_variable_size() */
+				do_serialize(destptr, maxbytes, "%s",
+							 *conf->variable ? *conf->variable : "");
+			}
+			break;
+
+		case PGC_ENUM:
+			{
+				struct config_enum *conf = (struct config_enum *) gconf;
+
+				do_serialize(destptr, maxbytes, "%s",
+							 config_enum_lookup_by_value(conf, *conf->variable));
+			}
+			break;
+	}
+
+	do_serialize(destptr, maxbytes, "%s",
+				 (gconf->sourcefile ? gconf->sourcefile : ""));
+
+	if (gconf->sourcefile && gconf->sourcefile[0])
+		do_serialize_binary(destptr, maxbytes, &gconf->sourceline,
+							sizeof(gconf->sourceline));
+
+	do_serialize_binary(destptr, maxbytes, &gconf->source,
+						sizeof(gconf->source));
+	do_serialize_binary(destptr, maxbytes, &gconf->scontext,
+						sizeof(gconf->scontext));
+}
+
+/*
+ * SerializeGUCState:
+ * Dumps the complete GUC state onto the memory location at start_address.
+ */
+void
+SerializeGUCState(Size maxsize, char *start_address)
+{
+	char	   *curptr;
+	Size		actual_size;
+	Size		bytes_left;
+	int			i;
+
+	/* Reserve space for saving the actual size of the guc state */
+	Assert(maxsize > sizeof(actual_size));
+	curptr = start_address + sizeof(actual_size);
+	bytes_left = maxsize - sizeof(actual_size);
+
+	for (i = 0; i < num_guc_variables; i++)
+		serialize_variable(&curptr, &bytes_left, guc_variables[i]);
+
+	/* Store actual size without assuming alignment of start_address. */
+	actual_size = maxsize - bytes_left - sizeof(actual_size);
+	memcpy(start_address, &actual_size, sizeof(actual_size));
+}
+
+/*
+ * read_gucstate:
+ * Actually it does not read anything, just returns the srcptr. But it does
+ * move the srcptr past the terminating zero byte, so that the caller is ready
+ * to read the next string.
+ */
+static char *
+read_gucstate(char **srcptr, char *srcend)
+{
+	char	   *retptr = *srcptr;
+	char	   *ptr;
+
+	if (*srcptr >= srcend)
+		elog(ERROR, "incomplete GUC state");
+
+	/* The string variables are all null terminated */
+	for (ptr = *srcptr; ptr < srcend && *ptr != '\0'; ptr++)
+		;
+
+	if (ptr >= srcend)
+		elog(ERROR, "could not find null terminator in GUC state");
+
+	/* Set the new position to the byte following the terminating NUL */
+	*srcptr = ptr + 1;
+
+	return retptr;
+}
+
+/* Binary read version of read_gucstate(). Copies into dest */
+static void
+read_gucstate_binary(char **srcptr, char *srcend, void *dest, Size size)
+{
+	if (*srcptr + size > srcend)
+		elog(ERROR, "incomplete GUC state");
+
+	memcpy(dest, *srcptr, size);
+	*srcptr += size;
+}
+
+/*
+ * Callback used to add a context message when reporting errors that occur
+ * while trying to restore GUCs in parallel workers.
+ */
+static void
+guc_restore_error_context_callback(void *arg)
+{
+	char	  **error_context_name_and_value = (char **) arg;
+
+	if (error_context_name_and_value)
+		errcontext("while setting parameter \"%s\" to \"%s\"",
+				   error_context_name_and_value[0],
+				   error_context_name_and_value[1]);
+}
+
+/*
+ * RestoreGUCState:
+ * Reads the GUC state at the specified address and sets this process's
+ * GUCs to match.
+ *
+ * Note that this provides the worker with only a very shallow view of the
+ * leader's GUC state: we'll know about the currently active values, but not
+ * about stacked or reset values.  That's fine since the worker is just
+ * executing one part of a query, within which the active values won't change
+ * and the stacked values are invisible.
+ */
+void
+RestoreGUCState(void *gucstate)
+{
+	char	   *varname,
+			   *varvalue,
+			   *varsourcefile;
+	int			varsourceline;
+	GucSource	varsource;
+	GucContext	varscontext;
+	char	   *srcptr = (char *) gucstate;
+	char	   *srcend;
+	Size		len;
+	int			i;
+	ErrorContextCallback error_context_callback;
+
+	/*
+	 * First, ensure that all potentially-shippable GUCs are reset to their
+	 * default values.  We must not touch those GUCs that the leader will
+	 * never ship, while there is no need to touch those that are shippable
+	 * but already have their default values.  Thus, this ends up being the
+	 * same test that SerializeGUCState uses, even though the sets of
+	 * variables involved may well be different since the leader's set of
+	 * variables-not-at-default-values can differ from the set that are
+	 * not-default in this freshly started worker.
+	 *
+	 * Once we have set all the potentially-shippable GUCs to default values,
+	 * restoring the GUCs that the leader sent (because they had non-default
+	 * values over there) leads us to exactly the set of GUC values that the
+	 * leader has.  This is true even though the worker may have initially
+	 * absorbed postgresql.conf settings that the leader hasn't yet seen, or
+	 * ALTER USER/DATABASE SET settings that were established after the leader
+	 * started.
+	 *
+	 * Note that ensuring all the potential target GUCs are at PGC_S_DEFAULT
+	 * also ensures that set_config_option won't refuse to set them because of
+	 * source-priority comparisons.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		/* Do nothing if non-shippable or if already at PGC_S_DEFAULT. */
+		if (can_skip_gucvar(gconf))
+			continue;
+
+		/*
+		 * We can use InitializeOneGUCOption to reset the GUC to default, but
+		 * first we must free any existing subsidiary data to avoid leaking
+		 * memory.  The stack must be empty, but we have to clean up all other
+		 * fields.  Beware that there might be duplicate value or "extra"
+		 * pointers.
+		 */
+		Assert(gconf->stack == NULL);
+		if (gconf->extra)
+			free(gconf->extra);
+		if (gconf->last_reported)	/* probably can't happen */
+			free(gconf->last_reported);
+		if (gconf->sourcefile)
+			free(gconf->sourcefile);
+		switch (gconf->vartype)
+		{
+			case PGC_BOOL:
+				{
+					struct config_bool *conf = (struct config_bool *) gconf;
+
+					if (conf->reset_extra && conf->reset_extra != gconf->extra)
+						free(conf->reset_extra);
+					break;
+				}
+			case PGC_INT:
+				{
+					struct config_int *conf = (struct config_int *) gconf;
+
+					if (conf->reset_extra && conf->reset_extra != gconf->extra)
+						free(conf->reset_extra);
+					break;
+				}
+			case PGC_REAL:
+				{
+					struct config_real *conf = (struct config_real *) gconf;
+
+					if (conf->reset_extra && conf->reset_extra != gconf->extra)
+						free(conf->reset_extra);
+					break;
+				}
+			case PGC_STRING:
+				{
+					struct config_string *conf = (struct config_string *) gconf;
+
+					if (*conf->variable)
+						free(*conf->variable);
+					if (conf->reset_val && conf->reset_val != *conf->variable)
+						free(conf->reset_val);
+					if (conf->reset_extra && conf->reset_extra != gconf->extra)
+						free(conf->reset_extra);
+					break;
+				}
+			case PGC_ENUM:
+				{
+					struct config_enum *conf = (struct config_enum *) gconf;
+
+					if (conf->reset_extra && conf->reset_extra != gconf->extra)
+						free(conf->reset_extra);
+					break;
+				}
+		}
+		/* Now we can reset the struct to PGS_S_DEFAULT state. */
+		InitializeOneGUCOption(gconf);
+	}
+
+	/* First item is the length of the subsequent data */
+	memcpy(&len, gucstate, sizeof(len));
+
+	srcptr += sizeof(len);
+	srcend = srcptr + len;
+
+	/* If the GUC value check fails, we want errors to show useful context. */
+	error_context_callback.callback = guc_restore_error_context_callback;
+	error_context_callback.previous = error_context_stack;
+	error_context_callback.arg = NULL;
+	error_context_stack = &error_context_callback;
+
+	/* Restore all the listed GUCs. */
+	while (srcptr < srcend)
+	{
+		int			result;
+		char	   *error_context_name_and_value[2];
+
+		varname = read_gucstate(&srcptr, srcend);
+		varvalue = read_gucstate(&srcptr, srcend);
+		varsourcefile = read_gucstate(&srcptr, srcend);
+		if (varsourcefile[0])
+			read_gucstate_binary(&srcptr, srcend,
+								 &varsourceline, sizeof(varsourceline));
+		else
+			varsourceline = 0;
+		read_gucstate_binary(&srcptr, srcend,
+							 &varsource, sizeof(varsource));
+		read_gucstate_binary(&srcptr, srcend,
+							 &varscontext, sizeof(varscontext));
+
+		error_context_name_and_value[0] = varname;
+		error_context_name_and_value[1] = varvalue;
+		error_context_callback.arg = &error_context_name_and_value[0];
+		result = set_config_option(varname, varvalue, varscontext, varsource,
+								   GUC_ACTION_SET, true, ERROR, true);
+		if (result <= 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_INTERNAL_ERROR),
+					 errmsg("parameter \"%s\" could not be set", varname)));
+		if (varsourcefile[0])
+			set_config_sourcefile(varname, varsourcefile, varsourceline);
+		error_context_callback.arg = NULL;
+	}
+
+	error_context_stack = error_context_callback.previous;
+}
+
+/*
+ * A little "long argument" simulation, although not quite GNU
+ * compliant. Takes a string of the form "some-option=some value" and
+ * returns name = "some_option" and value = "some value" in malloc'ed
+ * storage. Note that '-' is converted to '_' in the option name. If
+ * there is no '=' in the input string then value will be NULL.
+ */
+void
+ParseLongOption(const char *string, char **name, char **value)
+{
+	size_t		equal_pos;
+	char	   *cp;
+
+	AssertArg(string);
+	AssertArg(name);
+	AssertArg(value);
+
+	equal_pos = strcspn(string, "=");
+
+	if (string[equal_pos] == '=')
+	{
+		*name = guc_malloc(FATAL, equal_pos + 1);
+		strlcpy(*name, string, equal_pos + 1);
+
+		*value = guc_strdup(FATAL, &string[equal_pos + 1]);
+	}
+	else
+	{
+		/* no equal sign in string */
+		*name = guc_strdup(FATAL, string);
+		*value = NULL;
+	}
+
+	for (cp = *name; *cp; cp++)
+		if (*cp == '-')
+			*cp = '_';
+}
+
+
+/*
+ * Handle options fetched from pg_db_role_setting.setconfig,
+ * pg_proc.proconfig, etc.  Caller must specify proper context/source/action.
+ *
+ * The array parameter must be an array of TEXT (it must not be NULL).
+ */
+void
+ProcessGUCArray(ArrayType *array,
+				GucContext context, GucSource source, GucAction action)
+{
+	int			i;
+
+	Assert(array != NULL);
+	Assert(ARR_ELEMTYPE(array) == TEXTOID);
+	Assert(ARR_NDIM(array) == 1);
+	Assert(ARR_LBOUND(array)[0] == 1);
+
+	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+	{
+		Datum		d;
+		bool		isnull;
+		char	   *s;
+		char	   *name;
+		char	   *value;
+		char	   *namecopy;
+		char	   *valuecopy;
+
+		d = array_ref(array, 1, &i,
+					  -1 /* varlenarray */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  TYPALIGN_INT /* TEXT's typalign */ ,
+					  &isnull);
+
+		if (isnull)
+			continue;
+
+		s = TextDatumGetCString(d);
+
+		ParseLongOption(s, &name, &value);
+		if (!value)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("could not parse setting for parameter \"%s\"",
+							name)));
+			free(name);
+			continue;
+		}
+
+		/* free malloc'd strings immediately to avoid leak upon error */
+		namecopy = pstrdup(name);
+		free(name);
+		valuecopy = pstrdup(value);
+		free(value);
+
+		(void) set_config_option(namecopy, valuecopy,
+								 context, source,
+								 action, true, 0, false);
+
+		pfree(namecopy);
+		pfree(valuecopy);
+		pfree(s);
+	}
+}
+
+
+/*
+ * Add an entry to an option array.  The array parameter may be NULL
+ * to indicate the current table entry is NULL.
+ */
+ArrayType *
+GUCArrayAdd(ArrayType *array, const char *name, const char *value)
+{
+	struct config_generic *record;
+	Datum		datum;
+	char	   *newval;
+	ArrayType  *a;
+
+	Assert(name);
+	Assert(value);
+
+	/* test if the option is valid and we're allowed to set it */
+	(void) validate_option_array_item(name, value, false);
+
+	/* normalize name (converts obsolete GUC names to modern spellings) */
+	record = find_option(name, false, true, WARNING);
+	if (record)
+		name = record->name;
+
+	/* build new item for array */
+	newval = psprintf("%s=%s", name, value);
+	datum = CStringGetTextDatum(newval);
+
+	if (array)
+	{
+		int			index;
+		bool		isnull;
+		int			i;
+
+		Assert(ARR_ELEMTYPE(array) == TEXTOID);
+		Assert(ARR_NDIM(array) == 1);
+		Assert(ARR_LBOUND(array)[0] == 1);
+
+		index = ARR_DIMS(array)[0] + 1; /* add after end */
+
+		for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+		{
+			Datum		d;
+			char	   *current;
+
+			d = array_ref(array, 1, &i,
+						  -1 /* varlenarray */ ,
+						  -1 /* TEXT's typlen */ ,
+						  false /* TEXT's typbyval */ ,
+						  TYPALIGN_INT /* TEXT's typalign */ ,
+						  &isnull);
+			if (isnull)
+				continue;
+			current = TextDatumGetCString(d);
+
+			/* check for match up through and including '=' */
+			if (strncmp(current, newval, strlen(name) + 1) == 0)
+			{
+				index = i;
+				break;
+			}
+		}
+
+		a = array_set(array, 1, &index,
+					  datum,
+					  false,
+					  -1 /* varlena array */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  TYPALIGN_INT /* TEXT's typalign */ );
+	}
+	else
+		a = construct_array(&datum, 1,
+							TEXTOID,
+							-1, false, TYPALIGN_INT);
+
+	return a;
+}
+
+
+/*
+ * Delete an entry from an option array.  The array parameter may be NULL
+ * to indicate the current table entry is NULL.  Also, if the return value
+ * is NULL then a null should be stored.
+ */
+ArrayType *
+GUCArrayDelete(ArrayType *array, const char *name)
+{
+	struct config_generic *record;
+	ArrayType  *newarray;
+	int			i;
+	int			index;
+
+	Assert(name);
+
+	/* test if the option is valid and we're allowed to set it */
+	(void) validate_option_array_item(name, NULL, false);
+
+	/* normalize name (converts obsolete GUC names to modern spellings) */
+	record = find_option(name, false, true, WARNING);
+	if (record)
+		name = record->name;
+
+	/* if array is currently null, then surely nothing to delete */
+	if (!array)
+		return NULL;
+
+	newarray = NULL;
+	index = 1;
+
+	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+	{
+		Datum		d;
+		char	   *val;
+		bool		isnull;
+
+		d = array_ref(array, 1, &i,
+					  -1 /* varlenarray */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  TYPALIGN_INT /* TEXT's typalign */ ,
+					  &isnull);
+		if (isnull)
+			continue;
+		val = TextDatumGetCString(d);
+
+		/* ignore entry if it's what we want to delete */
+		if (strncmp(val, name, strlen(name)) == 0
+			&& val[strlen(name)] == '=')
+			continue;
+
+		/* else add it to the output array */
+		if (newarray)
+			newarray = array_set(newarray, 1, &index,
+								 d,
+								 false,
+								 -1 /* varlenarray */ ,
+								 -1 /* TEXT's typlen */ ,
+								 false /* TEXT's typbyval */ ,
+								 TYPALIGN_INT /* TEXT's typalign */ );
+		else
+			newarray = construct_array(&d, 1,
+									   TEXTOID,
+									   -1, false, TYPALIGN_INT);
+
+		index++;
+	}
+
+	return newarray;
+}
+
+
+/*
+ * Given a GUC array, delete all settings from it that our permission
+ * level allows: if superuser, delete them all; if regular user, only
+ * those that are PGC_USERSET
+ */
+ArrayType *
+GUCArrayReset(ArrayType *array)
+{
+	ArrayType  *newarray;
+	int			i;
+	int			index;
+
+	/* if array is currently null, nothing to do */
+	if (!array)
+		return NULL;
+
+	/* if we're superuser, we can delete everything, so just do it */
+	if (superuser())
+		return NULL;
+
+	newarray = NULL;
+	index = 1;
+
+	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+	{
+		Datum		d;
+		char	   *val;
+		char	   *eqsgn;
+		bool		isnull;
+
+		d = array_ref(array, 1, &i,
+					  -1 /* varlenarray */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  TYPALIGN_INT /* TEXT's typalign */ ,
+					  &isnull);
+		if (isnull)
+			continue;
+		val = TextDatumGetCString(d);
+
+		eqsgn = strchr(val, '=');
+		*eqsgn = '\0';
+
+		/* skip if we have permission to delete it */
+		if (validate_option_array_item(val, NULL, true))
+			continue;
+
+		/* else add it to the output array */
+		if (newarray)
+			newarray = array_set(newarray, 1, &index,
+								 d,
+								 false,
+								 -1 /* varlenarray */ ,
+								 -1 /* TEXT's typlen */ ,
+								 false /* TEXT's typbyval */ ,
+								 TYPALIGN_INT /* TEXT's typalign */ );
+		else
+			newarray = construct_array(&d, 1,
+									   TEXTOID,
+									   -1, false, TYPALIGN_INT);
+
+		index++;
+		pfree(val);
+	}
+
+	return newarray;
+}
+
+/*
+ * Validate a proposed option setting for GUCArrayAdd/Delete/Reset.
+ *
+ * name is the option name.  value is the proposed value for the Add case,
+ * or NULL for the Delete/Reset cases.  If skipIfNoPermissions is true, it's
+ * not an error to have no permissions to set the option.
+ *
+ * Returns true if OK, false if skipIfNoPermissions is true and user does not
+ * have permission to change this option (all other error cases result in an
+ * error being thrown).
+ */
+static bool
+validate_option_array_item(const char *name, const char *value,
+						   bool skipIfNoPermissions)
+
+{
+	struct config_generic *gconf;
+
+	/*
+	 * There are three cases to consider:
+	 *
+	 * name is a known GUC variable.  Check the value normally, check
+	 * permissions normally (i.e., allow if variable is USERSET, or if it's
+	 * SUSET and user is superuser).
+	 *
+	 * name is not known, but exists or can be created as a placeholder (i.e.,
+	 * it has a valid custom name).  We allow this case if you're a superuser,
+	 * otherwise not.  Superusers are assumed to know what they're doing. We
+	 * can't allow it for other users, because when the placeholder is
+	 * resolved it might turn out to be a SUSET variable;
+	 * define_custom_variable assumes we checked that.
+	 *
+	 * name is not known and can't be created as a placeholder.  Throw error,
+	 * unless skipIfNoPermissions is true, in which case return false.
+	 */
+	gconf = find_option(name, true, skipIfNoPermissions, ERROR);
+	if (!gconf)
+	{
+		/* not known, failed to make a placeholder */
+		return false;
+	}
+
+	if (gconf->flags & GUC_CUSTOM_PLACEHOLDER)
+	{
+		/*
+		 * We cannot do any meaningful check on the value, so only permissions
+		 * are useful to check.
+		 */
+		if (superuser())
+			return true;
+		if (skipIfNoPermissions)
+			return false;
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to set parameter \"%s\"", name)));
+	}
+
+	/* manual permissions check so we can avoid an error being thrown */
+	if (gconf->context == PGC_USERSET)
+		 /* ok */ ;
+	else if (gconf->context == PGC_SUSET && superuser())
+		 /* ok */ ;
+	else if (skipIfNoPermissions)
+		return false;
+	/* if a permissions error should be thrown, let set_config_option do it */
+
+	/* test for permissions and valid option value */
+	(void) set_config_option(name, value,
+							 superuser() ? PGC_SUSET : PGC_USERSET,
+							 PGC_S_TEST, GUC_ACTION_SET, false, 0, false);
+
+	return true;
+}
+
+
+/*
+ * Called by check_hooks that want to override the normal
+ * ERRCODE_INVALID_PARAMETER_VALUE SQLSTATE for check hook failures.
+ *
+ * Note that GUC_check_errmsg() etc are just macros that result in a direct
+ * assignment to the associated variables.  That is ugly, but forced by the
+ * limitations of C's macro mechanisms.
+ */
+void
+GUC_check_errcode(int sqlerrcode)
+{
+	GUC_check_errcode_value = sqlerrcode;
+}
+
+
+/*
+ * Convenience functions to manage calling a variable's check_hook.
+ * These mostly take care of the protocol for letting check hooks supply
+ * portions of the error report on failure.
+ */
+
+static bool
+call_bool_check_hook(struct config_bool *conf, bool *newval, void **extra,
+					 GucSource source, int elevel)
+{
+	/* Quick success if no hook */
+	if (!conf->check_hook)
+		return true;
+
+	/* Reset variables that might be set by hook */
+	GUC_check_errcode_value = ERRCODE_INVALID_PARAMETER_VALUE;
+	GUC_check_errmsg_string = NULL;
+	GUC_check_errdetail_string = NULL;
+	GUC_check_errhint_string = NULL;
+
+	if (!conf->check_hook(newval, extra, source))
+	{
+		ereport(elevel,
+				(errcode(GUC_check_errcode_value),
+				 GUC_check_errmsg_string ?
+				 errmsg_internal("%s", GUC_check_errmsg_string) :
+				 errmsg("invalid value for parameter \"%s\": %d",
+						conf->gen.name, (int) *newval),
+				 GUC_check_errdetail_string ?
+				 errdetail_internal("%s", GUC_check_errdetail_string) : 0,
+				 GUC_check_errhint_string ?
+				 errhint("%s", GUC_check_errhint_string) : 0));
+		/* Flush any strings created in ErrorContext */
+		FlushErrorState();
+		return false;
+	}
+
+	return true;
+}
+
+static bool
+call_int_check_hook(struct config_int *conf, int *newval, void **extra,
+					GucSource source, int elevel)
+{
+	/* Quick success if no hook */
+	if (!conf->check_hook)
+		return true;
+
+	/* Reset variables that might be set by hook */
+	GUC_check_errcode_value = ERRCODE_INVALID_PARAMETER_VALUE;
+	GUC_check_errmsg_string = NULL;
+	GUC_check_errdetail_string = NULL;
+	GUC_check_errhint_string = NULL;
+
+	if (!conf->check_hook(newval, extra, source))
+	{
+		ereport(elevel,
+				(errcode(GUC_check_errcode_value),
+				 GUC_check_errmsg_string ?
+				 errmsg_internal("%s", GUC_check_errmsg_string) :
+				 errmsg("invalid value for parameter \"%s\": %d",
+						conf->gen.name, *newval),
+				 GUC_check_errdetail_string ?
+				 errdetail_internal("%s", GUC_check_errdetail_string) : 0,
+				 GUC_check_errhint_string ?
+				 errhint("%s", GUC_check_errhint_string) : 0));
+		/* Flush any strings created in ErrorContext */
+		FlushErrorState();
+		return false;
+	}
+
+	return true;
+}
+
+static bool
+call_real_check_hook(struct config_real *conf, double *newval, void **extra,
+					 GucSource source, int elevel)
+{
+	/* Quick success if no hook */
+	if (!conf->check_hook)
+		return true;
+
+	/* Reset variables that might be set by hook */
+	GUC_check_errcode_value = ERRCODE_INVALID_PARAMETER_VALUE;
+	GUC_check_errmsg_string = NULL;
+	GUC_check_errdetail_string = NULL;
+	GUC_check_errhint_string = NULL;
+
+	if (!conf->check_hook(newval, extra, source))
+	{
+		ereport(elevel,
+				(errcode(GUC_check_errcode_value),
+				 GUC_check_errmsg_string ?
+				 errmsg_internal("%s", GUC_check_errmsg_string) :
+				 errmsg("invalid value for parameter \"%s\": %g",
+						conf->gen.name, *newval),
+				 GUC_check_errdetail_string ?
+				 errdetail_internal("%s", GUC_check_errdetail_string) : 0,
+				 GUC_check_errhint_string ?
+				 errhint("%s", GUC_check_errhint_string) : 0));
+		/* Flush any strings created in ErrorContext */
+		FlushErrorState();
+		return false;
+	}
+
+	return true;
+}
+
+static bool
+call_string_check_hook(struct config_string *conf, char **newval, void **extra,
+					   GucSource source, int elevel)
+{
+	volatile bool result = true;
+
+	/* Quick success if no hook */
+	if (!conf->check_hook)
+		return true;
+
+	/*
+	 * If elevel is ERROR, or if the check_hook itself throws an elog
+	 * (undesirable, but not always avoidable), make sure we don't leak the
+	 * already-malloc'd newval string.
+	 */
+	PG_TRY();
+	{
+		/* Reset variables that might be set by hook */
+		GUC_check_errcode_value = ERRCODE_INVALID_PARAMETER_VALUE;
+		GUC_check_errmsg_string = NULL;
+		GUC_check_errdetail_string = NULL;
+		GUC_check_errhint_string = NULL;
+
+		if (!conf->check_hook(newval, extra, source))
+		{
+			ereport(elevel,
+					(errcode(GUC_check_errcode_value),
+					 GUC_check_errmsg_string ?
+					 errmsg_internal("%s", GUC_check_errmsg_string) :
+					 errmsg("invalid value for parameter \"%s\": \"%s\"",
+							conf->gen.name, *newval ? *newval : ""),
+					 GUC_check_errdetail_string ?
+					 errdetail_internal("%s", GUC_check_errdetail_string) : 0,
+					 GUC_check_errhint_string ?
+					 errhint("%s", GUC_check_errhint_string) : 0));
+			/* Flush any strings created in ErrorContext */
+			FlushErrorState();
+			result = false;
+		}
+	}
+	PG_CATCH();
+	{
+		free(*newval);
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+
+	return result;
+}
+
+static bool
+call_enum_check_hook(struct config_enum *conf, int *newval, void **extra,
+					 GucSource source, int elevel)
+{
+	/* Quick success if no hook */
+	if (!conf->check_hook)
+		return true;
+
+	/* Reset variables that might be set by hook */
+	GUC_check_errcode_value = ERRCODE_INVALID_PARAMETER_VALUE;
+	GUC_check_errmsg_string = NULL;
+	GUC_check_errdetail_string = NULL;
+	GUC_check_errhint_string = NULL;
+
+	if (!conf->check_hook(newval, extra, source))
+	{
+		ereport(elevel,
+				(errcode(GUC_check_errcode_value),
+				 GUC_check_errmsg_string ?
+				 errmsg_internal("%s", GUC_check_errmsg_string) :
+				 errmsg("invalid value for parameter \"%s\": \"%s\"",
+						conf->gen.name,
+						config_enum_lookup_by_value(conf, *newval)),
+				 GUC_check_errdetail_string ?
+				 errdetail_internal("%s", GUC_check_errdetail_string) : 0,
+				 GUC_check_errhint_string ?
+				 errhint("%s", GUC_check_errhint_string) : 0));
+		/* Flush any strings created in ErrorContext */
+		FlushErrorState();
+		return false;
+	}
+
+	return true;
+}
+
+
+/*
+ * check_hook, assign_hook and show_hook subroutines
+ */
+
+static bool
+check_wal_consistency_checking(char **newval, void **extra, GucSource source)
+{
+	char	   *rawstring;
+	List	   *elemlist;
+	ListCell   *l;
+	bool		newwalconsistency[RM_MAX_ID + 1];
+
+	/* Initialize the array */
+	MemSet(newwalconsistency, 0, (RM_MAX_ID + 1) * sizeof(bool));
+
+	/* Need a modifiable copy of string */
+	rawstring = pstrdup(*newval);
+
+	/* Parse string into list of identifiers */
+	if (!SplitIdentifierString(rawstring, ',', &elemlist))
+	{
+		/* syntax error in list */
+		GUC_check_errdetail("List syntax is invalid.");
+		pfree(rawstring);
+		list_free(elemlist);
+		return false;
+	}
+
+	foreach(l, elemlist)
+	{
+		char	   *tok = (char *) lfirst(l);
+		bool		found = false;
+		RmgrId		rmid;
+
+		/* Check for 'all'. */
+		if (pg_strcasecmp(tok, "all") == 0)
+		{
+			for (rmid = 0; rmid <= RM_MAX_ID; rmid++)
+				if (RmgrTable[rmid].rm_mask != NULL)
+					newwalconsistency[rmid] = true;
+			found = true;
+		}
+		else
+		{
+			/*
+			 * Check if the token matches with any individual resource
+			 * manager.
+			 */
+			for (rmid = 0; rmid <= RM_MAX_ID; rmid++)
+			{
+				if (pg_strcasecmp(tok, RmgrTable[rmid].rm_name) == 0 &&
+					RmgrTable[rmid].rm_mask != NULL)
+				{
+					newwalconsistency[rmid] = true;
+					found = true;
+				}
+			}
+		}
+
+		/* If a valid resource manager is found, check for the next one. */
+		if (!found)
+		{
+			GUC_check_errdetail("Unrecognized key word: \"%s\".", tok);
+			pfree(rawstring);
+			list_free(elemlist);
+			return false;
+		}
+	}
+
+	pfree(rawstring);
+	list_free(elemlist);
+
+	/* assign new value */
+	*extra = guc_malloc(ERROR, (RM_MAX_ID + 1) * sizeof(bool));
+	memcpy(*extra, newwalconsistency, (RM_MAX_ID + 1) * sizeof(bool));
+	return true;
+}
+
+static void
+assign_wal_consistency_checking(const char *newval, void *extra)
+{
+	wal_consistency_checking = (bool *) extra;
+}
+
+static bool
+check_log_destination(char **newval, void **extra, GucSource source)
+{
+	char	   *rawstring;
+	List	   *elemlist;
+	ListCell   *l;
+	int			newlogdest = 0;
+	int		   *myextra;
+
+	/* Need a modifiable copy of string */
+	rawstring = pstrdup(*newval);
+
+	/* Parse string into list of identifiers */
+	if (!SplitIdentifierString(rawstring, ',', &elemlist))
+	{
+		/* syntax error in list */
+		GUC_check_errdetail("List syntax is invalid.");
+		pfree(rawstring);
+		list_free(elemlist);
+		return false;
+	}
+
+	foreach(l, elemlist)
+	{
+		char	   *tok = (char *) lfirst(l);
+
+		if (pg_strcasecmp(tok, "stderr") == 0)
+			newlogdest |= LOG_DESTINATION_STDERR;
+		else if (pg_strcasecmp(tok, "csvlog") == 0)
+			newlogdest |= LOG_DESTINATION_CSVLOG;
+#ifdef HAVE_SYSLOG
+		else if (pg_strcasecmp(tok, "syslog") == 0)
+			newlogdest |= LOG_DESTINATION_SYSLOG;
+#endif
+#ifdef WIN32
+		else if (pg_strcasecmp(tok, "eventlog") == 0)
+			newlogdest |= LOG_DESTINATION_EVENTLOG;
+#endif
+		else
+		{
+			GUC_check_errdetail("Unrecognized key word: \"%s\".", tok);
+			pfree(rawstring);
+			list_free(elemlist);
+			return false;
+		}
+	}
+
+	pfree(rawstring);
+	list_free(elemlist);
+
+	myextra = (int *) guc_malloc(ERROR, sizeof(int));
+	*myextra = newlogdest;
+	*extra = (void *) myextra;
+
+	return true;
+}
+
+static void
+assign_log_destination(const char *newval, void *extra)
+{
+	Log_destination = *((int *) extra);
+}
+
+static void
+assign_syslog_facility(int newval, void *extra)
+{
+#ifdef HAVE_SYSLOG
+	set_syslog_parameters(syslog_ident_str ? syslog_ident_str : "postgres",
+						  newval);
+#endif
+	/* Without syslog support, just ignore it */
+}
+
+static void
+assign_syslog_ident(const char *newval, void *extra)
+{
+#ifdef HAVE_SYSLOG
+	set_syslog_parameters(newval, syslog_facility);
+#endif
+	/* Without syslog support, it will always be set to "none", so ignore */
+}
+
+
+static void
+assign_session_replication_role(int newval, void *extra)
+{
+	/*
+	 * Must flush the plan cache when changing replication role; but don't
+	 * flush unnecessarily.
+	 */
+	if (SessionReplicationRole != newval)
+		ResetPlanCache();
+}
+
+static bool
+check_temp_buffers(int *newval, void **extra, GucSource source)
+{
+	/*
+	 * Once local buffers have been initialized, it's too late to change this.
+	 * However, if this is only a test call, allow it.
+	 */
+	if (source != PGC_S_TEST && NLocBuffer && NLocBuffer != *newval)
+	{
+		GUC_check_errdetail("\"temp_buffers\" cannot be changed after any temporary tables have been accessed in the session.");
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_bonjour(bool *newval, void **extra, GucSource source)
+{
+#ifndef USE_BONJOUR
+	if (*newval)
+	{
+		GUC_check_errmsg("Bonjour is not supported by this build");
+		return false;
+	}
+#endif
+	return true;
+}
+
+static bool
+check_ssl(bool *newval, void **extra, GucSource source)
+{
+#ifndef USE_SSL
+	if (*newval)
+	{
+		GUC_check_errmsg("SSL is not supported by this build");
+		return false;
+	}
+#endif
+	return true;
+}
+
+static bool
+check_stage_log_stats(bool *newval, void **extra, GucSource source)
+{
+	if (*newval && log_statement_stats)
+	{
+		GUC_check_errdetail("Cannot enable parameter when \"log_statement_stats\" is true.");
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_log_stats(bool *newval, void **extra, GucSource source)
+{
+	if (*newval &&
+		(log_parser_stats || log_planner_stats || log_executor_stats))
+	{
+		GUC_check_errdetail("Cannot enable \"log_statement_stats\" when "
+							"\"log_parser_stats\", \"log_planner_stats\", "
+							"or \"log_executor_stats\" is true.");
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_canonical_path(char **newval, void **extra, GucSource source)
+{
+	/*
+	 * Since canonicalize_path never enlarges the string, we can just modify
+	 * newval in-place.  But watch out for NULL, which is the default value
+	 * for external_pid_file.
+	 */
+	if (*newval)
+		canonicalize_path(*newval);
+	return true;
+}
+
+static bool
+check_timezone_abbreviations(char **newval, void **extra, GucSource source)
+{
+	/*
+	 * The boot_val given above for timezone_abbreviations is NULL. When we
+	 * see this we just do nothing.  If this value isn't overridden from the
+	 * config file then pg_timezone_abbrev_initialize() will eventually
+	 * replace it with "Default".  This hack has two purposes: to avoid
+	 * wasting cycles loading values that might soon be overridden from the
+	 * config file, and to avoid trying to read the timezone abbrev files
+	 * during InitializeGUCOptions().  The latter doesn't work in an
+	 * EXEC_BACKEND subprocess because my_exec_path hasn't been set yet and so
+	 * we can't locate PGSHAREDIR.
+	 */
+	if (*newval == NULL)
+	{
+		Assert(source == PGC_S_DEFAULT);
+		return true;
+	}
+
+	/* OK, load the file and produce a malloc'd TimeZoneAbbrevTable */
+	*extra = load_tzoffsets(*newval);
+
+	/* tzparser.c returns NULL on failure, reporting via GUC_check_errmsg */
+	if (!*extra)
+		return false;
+
+	return true;
+}
+
+static void
+assign_timezone_abbreviations(const char *newval, void *extra)
+{
+	/* Do nothing for the boot_val default of NULL */
+	if (!extra)
+		return;
+
+	InstallTimeZoneAbbrevs((TimeZoneAbbrevTable *) extra);
+}
+
+/*
+ * pg_timezone_abbrev_initialize --- set default value if not done already
+ *
+ * This is called after initial loading of postgresql.conf.  If no
+ * timezone_abbreviations setting was found therein, select default.
+ * If a non-default value is already installed, nothing will happen.
+ *
+ * This can also be called from ProcessConfigFile to establish the default
+ * value after a postgresql.conf entry for it is removed.
+ */
+static void
+pg_timezone_abbrev_initialize(void)
+{
+	SetConfigOption("timezone_abbreviations", "Default",
+					PGC_POSTMASTER, PGC_S_DYNAMIC_DEFAULT);
+}
+
+static const char *
+show_archive_command(void)
+{
+	if (XLogArchivingActive())
+		return XLogArchiveCommand;
+	else
+		return "(disabled)";
+}
+
+static void
+assign_tcp_keepalives_idle(int newval, void *extra)
+{
+	/*
+	 * The kernel API provides no way to test a value without setting it; and
+	 * once we set it we might fail to unset it.  So there seems little point
+	 * in fully implementing the check-then-assign GUC API for these
+	 * variables.  Instead we just do the assignment on demand.  pqcomm.c
+	 * reports any problems via ereport(LOG).
+	 *
+	 * This approach means that the GUC value might have little to do with the
+	 * actual kernel value, so we use a show_hook that retrieves the kernel
+	 * value rather than trusting GUC's copy.
+	 */
+	(void) pq_setkeepalivesidle(newval, MyProcPort);
+}
+
+static const char *
+show_tcp_keepalives_idle(void)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	static char nbuf[16];
+
+	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivesidle(MyProcPort));
+	return nbuf;
+}
+
+static void
+assign_tcp_keepalives_interval(int newval, void *extra)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	(void) pq_setkeepalivesinterval(newval, MyProcPort);
+}
+
+static const char *
+show_tcp_keepalives_interval(void)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	static char nbuf[16];
+
+	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivesinterval(MyProcPort));
+	return nbuf;
+}
+
+static void
+assign_tcp_keepalives_count(int newval, void *extra)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	(void) pq_setkeepalivescount(newval, MyProcPort);
+}
+
+static const char *
+show_tcp_keepalives_count(void)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	static char nbuf[16];
+
+	snprintf(nbuf, sizeof(nbuf), "%d", pq_getkeepalivescount(MyProcPort));
+	return nbuf;
+}
+
+static void
+assign_tcp_user_timeout(int newval, void *extra)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	(void) pq_settcpusertimeout(newval, MyProcPort);
+}
+
+static const char *
+show_tcp_user_timeout(void)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	static char nbuf[16];
+
+	snprintf(nbuf, sizeof(nbuf), "%d", pq_gettcpusertimeout(MyProcPort));
+	return nbuf;
+}
+
+static bool
+check_maxconnections(int *newval, void **extra, GucSource source)
+{
+	if (*newval + autovacuum_max_workers + 1 +
+		max_worker_processes + max_wal_senders > MAX_BACKENDS)
+		return false;
+	return true;
+}
+
+static bool
+check_autovacuum_max_workers(int *newval, void **extra, GucSource source)
+{
+	if (MaxConnections + *newval + 1 +
+		max_worker_processes + max_wal_senders > MAX_BACKENDS)
+		return false;
+	return true;
+}
+
+static bool
+check_max_wal_senders(int *newval, void **extra, GucSource source)
+{
+	if (MaxConnections + autovacuum_max_workers + 1 +
+		max_worker_processes + *newval > MAX_BACKENDS)
+		return false;
+	return true;
+}
+
+static bool
+check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
+{
+	/*
+	 * -1 indicates fallback.
+	 *
+	 * If we haven't yet changed the boot_val default of -1, just let it be.
+	 * Autovacuum will look to maintenance_work_mem instead.
+	 */
+	if (*newval == -1)
+		return true;
+
+	/*
+	 * We clamp manually-set values to at least 1MB.  Since
+	 * maintenance_work_mem is always set to at least this value, do the same
+	 * here.
+	 */
+	if (*newval < 1024)
+		*newval = 1024;
+
+	return true;
+}
+
+static bool
+check_max_worker_processes(int *newval, void **extra, GucSource source)
+{
+	if (MaxConnections + autovacuum_max_workers + 1 +
+		*newval + max_wal_senders > MAX_BACKENDS)
+		return false;
+	return true;
+}
+
+static bool
+check_effective_io_concurrency(int *newval, void **extra, GucSource source)
+{
+#ifndef USE_PREFETCH
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("effective_io_concurrency must be set to 0 on platforms that lack posix_fadvise().");
+		return false;
+	}
+#endif							/* USE_PREFETCH */
+	return true;
+}
+
+static bool
+check_maintenance_io_concurrency(int *newval, void **extra, GucSource source)
+{
+#ifndef USE_PREFETCH
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("maintenance_io_concurrency must be set to 0 on platforms that lack posix_fadvise().");
+		return false;
+	}
+#endif							/* USE_PREFETCH */
+	return true;
+}
+
+static bool
+check_huge_page_size(int *newval, void **extra, GucSource source)
+{
+#if !(defined(MAP_HUGE_MASK) && defined(MAP_HUGE_SHIFT))
+	/* Recent enough Linux only, for now.  See GetHugePageSize(). */
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("huge_page_size must be 0 on this platform.");
+		return false;
+	}
+#endif
+	return true;
+}
+
+static bool
+check_client_connection_check_interval(int *newval, void **extra, GucSource source)
+{
+#ifndef POLLRDHUP
+	/* Linux only, for now.  See pq_check_connection(). */
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("client_connection_check_interval must be set to 0 on platforms that lack POLLRDHUP.");
+		return false;
+	}
+#endif
+	return true;
+}
+
+static void
+assign_pgstat_temp_directory(const char *newval, void *extra)
+{
+	/* check_canonical_path already canonicalized newval for us */
+	char	   *dname;
+	char	   *tname;
+	char	   *fname;
+
+	/* directory */
+	dname = guc_malloc(ERROR, strlen(newval) + 1);	/* runtime dir */
+	sprintf(dname, "%s", newval);
+
+	/* global stats */
+	tname = guc_malloc(ERROR, strlen(newval) + 12); /* /global.tmp */
+	sprintf(tname, "%s/global.tmp", newval);
+	fname = guc_malloc(ERROR, strlen(newval) + 13); /* /global.stat */
+	sprintf(fname, "%s/global.stat", newval);
+
+	if (pgstat_stat_directory)
+		free(pgstat_stat_directory);
+	pgstat_stat_directory = dname;
+	if (pgstat_stat_tmpname)
+		free(pgstat_stat_tmpname);
+	pgstat_stat_tmpname = tname;
+	if (pgstat_stat_filename)
+		free(pgstat_stat_filename);
+	pgstat_stat_filename = fname;
+}
+
+static bool
+check_application_name(char **newval, void **extra, GucSource source)
+{
+	/* Only allow clean ASCII chars in the application name */
+	pg_clean_ascii(*newval);
+
+	return true;
+}
+
+static void
+assign_application_name(const char *newval, void *extra)
+{
+	/* Update the pg_stat_activity view */
+	pgstat_report_appname(newval);
+}
+
+static bool
+check_cluster_name(char **newval, void **extra, GucSource source)
+{
+	/* Only allow clean ASCII chars in the cluster name */
+	pg_clean_ascii(*newval);
+
+	return true;
+}
+
+static const char *
+show_unix_socket_permissions(void)
+{
+	static char buf[12];
+
+	snprintf(buf, sizeof(buf), "%04o", Unix_socket_permissions);
+	return buf;
+}
+
+static const char *
+show_log_file_mode(void)
+{
+	static char buf[12];
+
+	snprintf(buf, sizeof(buf), "%04o", Log_file_mode);
+	return buf;
+}
+
+static const char *
+show_data_directory_mode(void)
+{
+	static char buf[12];
+
+	snprintf(buf, sizeof(buf), "%04o", data_directory_mode);
+	return buf;
+}
+
+static const char *
+show_in_hot_standby(void)
+{
+	/*
+	 * We display the actual state based on shared memory, so that this GUC
+	 * reports up-to-date state if examined intra-query.  The underlying
+	 * variable in_hot_standby changes only when we transmit a new value to
+	 * the client.
+	 */
+	return RecoveryInProgress() ? "on" : "off";
+}
+
+/*
+ * We split the input string, where commas separate function names
+ * and certain whitespace chars are ignored, into a \0-separated (and
+ * \0\0-terminated) list of function names.  This formulation allows
+ * easy scanning when an error is thrown while avoiding the use of
+ * non-reentrant strtok(), as well as keeping the output data in a
+ * single palloc() chunk.
+ */
+static bool
+check_backtrace_functions(char **newval, void **extra, GucSource source)
+{
+	int			newvallen = strlen(*newval);
+	char	   *someval;
+	int			validlen;
+	int			i;
+	int			j;
+
+	/*
+	 * Allow characters that can be C identifiers and commas as separators, as
+	 * well as some whitespace for readability.
+	 */
+	validlen = strspn(*newval,
+					  "0123456789_"
+					  "abcdefghijklmnopqrstuvwxyz"
+					  "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+					  ", \n\t");
+	if (validlen != newvallen)
+	{
+		GUC_check_errdetail("invalid character");
+		return false;
+	}
+
+	if (*newval[0] == '\0')
+	{
+		*extra = NULL;
+		return true;
+	}
+
+	/*
+	 * Allocate space for the output and create the copy.  We could discount
+	 * whitespace chars to save some memory, but it doesn't seem worth the
+	 * trouble.
+	 */
+	someval = guc_malloc(ERROR, newvallen + 1 + 1);
+	for (i = 0, j = 0; i < newvallen; i++)
+	{
+		if ((*newval)[i] == ',')
+			someval[j++] = '\0';	/* next item */
+		else if ((*newval)[i] == ' ' ||
+				 (*newval)[i] == '\n' ||
+				 (*newval)[i] == '\t')
+			;					/* ignore these */
+		else
+			someval[j++] = (*newval)[i];	/* copy anything else */
+	}
+
+	/* two \0s end the setting */
+	someval[j] = '\0';
+	someval[j + 1] = '\0';
+
+	*extra = someval;
+	return true;
+}
+
+static void
+assign_backtrace_functions(const char *newval, void *extra)
+{
+	backtrace_symbol_list = (char *) extra;
+}
+
+static bool
+check_recovery_target_timeline(char **newval, void **extra, GucSource source)
+{
+	RecoveryTargetTimeLineGoal rttg;
+	RecoveryTargetTimeLineGoal *myextra;
+
+	if (strcmp(*newval, "current") == 0)
+		rttg = RECOVERY_TARGET_TIMELINE_CONTROLFILE;
+	else if (strcmp(*newval, "latest") == 0)
+		rttg = RECOVERY_TARGET_TIMELINE_LATEST;
+	else
+	{
+		rttg = RECOVERY_TARGET_TIMELINE_NUMERIC;
+
+		errno = 0;
+		strtoul(*newval, NULL, 0);
+		if (errno == EINVAL || errno == ERANGE)
+		{
+			GUC_check_errdetail("recovery_target_timeline is not a valid number.");
+			return false;
+		}
+	}
+
+	myextra = (RecoveryTargetTimeLineGoal *) guc_malloc(ERROR, sizeof(RecoveryTargetTimeLineGoal));
+	*myextra = rttg;
+	*extra = (void *) myextra;
+
+	return true;
+}
+
+static void
+assign_recovery_target_timeline(const char *newval, void *extra)
+{
+	recoveryTargetTimeLineGoal = *((RecoveryTargetTimeLineGoal *) extra);
+	if (recoveryTargetTimeLineGoal == RECOVERY_TARGET_TIMELINE_NUMERIC)
+		recoveryTargetTLIRequested = (TimeLineID) strtoul(newval, NULL, 0);
+	else
+		recoveryTargetTLIRequested = 0;
+}
+
+/*
+ * Recovery target settings: Only one of the several recovery_target* settings
+ * may be set.  Setting a second one results in an error.  The global variable
+ * recoveryTarget tracks which kind of recovery target was chosen.  Other
+ * variables store the actual target value (for example a string or a xid).
+ * The assign functions of the parameters check whether a competing parameter
+ * was already set.  But we want to allow setting the same parameter multiple
+ * times.  We also want to allow unsetting a parameter and setting a different
+ * one, so we unset recoveryTarget when the parameter is set to an empty
+ * string.
+ */
+
+static void
+pg_attribute_noreturn()
+error_multiple_recovery_targets(void)
+{
+	ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			 errmsg("multiple recovery targets specified"),
+			 errdetail("At most one of recovery_target, recovery_target_lsn, recovery_target_name, recovery_target_time, recovery_target_xid may be set.")));
+}
+
+static bool
+check_recovery_target(char **newval, void **extra, GucSource source)
+{
+	if (strcmp(*newval, "immediate") != 0 && strcmp(*newval, "") != 0)
+	{
+		GUC_check_errdetail("The only allowed value is \"immediate\".");
+		return false;
+	}
+	return true;
+}
+
+static void
+assign_recovery_target(const char *newval, void *extra)
+{
+	if (recoveryTarget != RECOVERY_TARGET_UNSET &&
+		recoveryTarget != RECOVERY_TARGET_IMMEDIATE)
+		error_multiple_recovery_targets();
+
+	if (newval && strcmp(newval, "") != 0)
+		recoveryTarget = RECOVERY_TARGET_IMMEDIATE;
+	else
+		recoveryTarget = RECOVERY_TARGET_UNSET;
+}
+
+static bool
+check_recovery_target_xid(char **newval, void **extra, GucSource source)
+{
+	if (strcmp(*newval, "") != 0)
+	{
+		TransactionId xid;
+		TransactionId *myextra;
+
+		errno = 0;
+		xid = (TransactionId) pg_strtouint64(*newval, NULL, 0);
+		if (errno == EINVAL || errno == ERANGE)
+			return false;
+
+		myextra = (TransactionId *) guc_malloc(ERROR, sizeof(TransactionId));
+		*myextra = xid;
+		*extra = (void *) myextra;
+	}
+	return true;
+}
+
+static void
+assign_recovery_target_xid(const char *newval, void *extra)
+{
+	if (recoveryTarget != RECOVERY_TARGET_UNSET &&
+		recoveryTarget != RECOVERY_TARGET_XID)
+		error_multiple_recovery_targets();
+
+	if (newval && strcmp(newval, "") != 0)
+	{
+		recoveryTarget = RECOVERY_TARGET_XID;
+		recoveryTargetXid = *((TransactionId *) extra);
+	}
+	else
+		recoveryTarget = RECOVERY_TARGET_UNSET;
+}
+
+/*
+ * The interpretation of the recovery_target_time string can depend on the
+ * time zone setting, so we need to wait until after all GUC processing is
+ * done before we can do the final parsing of the string.  This check function
+ * only does a parsing pass to catch syntax errors, but we store the string
+ * and parse it again when we need to use it.
+ */
+static bool
+check_recovery_target_time(char **newval, void **extra, GucSource source)
+{
+	if (strcmp(*newval, "") != 0)
+	{
+		/* reject some special values */
+		if (strcmp(*newval, "now") == 0 ||
+			strcmp(*newval, "today") == 0 ||
+			strcmp(*newval, "tomorrow") == 0 ||
+			strcmp(*newval, "yesterday") == 0)
+		{
+			return false;
+		}
+
+		/*
+		 * parse timestamp value (see also timestamptz_in())
+		 */
+		{
+			char	   *str = *newval;
+			fsec_t		fsec;
+			struct pg_tm tt,
+					   *tm = &tt;
+			int			tz;
+			int			dtype;
+			int			nf;
+			int			dterr;
+			char	   *field[MAXDATEFIELDS];
+			int			ftype[MAXDATEFIELDS];
+			char		workbuf[MAXDATELEN + MAXDATEFIELDS];
+			TimestampTz timestamp;
+
+			dterr = ParseDateTime(str, workbuf, sizeof(workbuf),
+								  field, ftype, MAXDATEFIELDS, &nf);
+			if (dterr == 0)
+				dterr = DecodeDateTime(field, ftype, nf, &dtype, tm, &fsec, &tz);
+			if (dterr != 0)
+				return false;
+			if (dtype != DTK_DATE)
+				return false;
+
+			if (tm2timestamp(tm, fsec, &tz, &timestamp) != 0)
+			{
+				GUC_check_errdetail("timestamp out of range: \"%s\"", str);
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
+static void
+assign_recovery_target_time(const char *newval, void *extra)
+{
+	if (recoveryTarget != RECOVERY_TARGET_UNSET &&
+		recoveryTarget != RECOVERY_TARGET_TIME)
+		error_multiple_recovery_targets();
+
+	if (newval && strcmp(newval, "") != 0)
+		recoveryTarget = RECOVERY_TARGET_TIME;
+	else
+		recoveryTarget = RECOVERY_TARGET_UNSET;
+}
+
+static bool
+check_recovery_target_name(char **newval, void **extra, GucSource source)
+{
+	/* Use the value of newval directly */
+	if (strlen(*newval) >= MAXFNAMELEN)
+	{
+		GUC_check_errdetail("%s is too long (maximum %d characters).",
+							"recovery_target_name", MAXFNAMELEN - 1);
+		return false;
+	}
+	return true;
+}
+
+static void
+assign_recovery_target_name(const char *newval, void *extra)
+{
+	if (recoveryTarget != RECOVERY_TARGET_UNSET &&
+		recoveryTarget != RECOVERY_TARGET_NAME)
+		error_multiple_recovery_targets();
+
+	if (newval && strcmp(newval, "") != 0)
+	{
+		recoveryTarget = RECOVERY_TARGET_NAME;
+		recoveryTargetName = newval;
+	}
+	else
+		recoveryTarget = RECOVERY_TARGET_UNSET;
+}
+
+static bool
+check_recovery_target_lsn(char **newval, void **extra, GucSource source)
+{
+	if (strcmp(*newval, "") != 0)
+	{
+		XLogRecPtr	lsn;
+		XLogRecPtr *myextra;
+		bool		have_error = false;
+
+		lsn = pg_lsn_in_internal(*newval, &have_error);
+		if (have_error)
+			return false;
+
+		myextra = (XLogRecPtr *) guc_malloc(ERROR, sizeof(XLogRecPtr));
+		*myextra = lsn;
+		*extra = (void *) myextra;
+	}
+	return true;
+}
+
+static void
+assign_recovery_target_lsn(const char *newval, void *extra)
+{
+	if (recoveryTarget != RECOVERY_TARGET_UNSET &&
+		recoveryTarget != RECOVERY_TARGET_LSN)
+		error_multiple_recovery_targets();
+
+	if (newval && strcmp(newval, "") != 0)
+	{
+		recoveryTarget = RECOVERY_TARGET_LSN;
+		recoveryTargetLSN = *((XLogRecPtr *) extra);
+	}
+	else
+		recoveryTarget = RECOVERY_TARGET_UNSET;
+}
+
+static bool
+check_primary_slot_name(char **newval, void **extra, GucSource source)
+{
+	if (*newval && strcmp(*newval, "") != 0 &&
+		!ReplicationSlotValidateName(*newval, WARNING))
+		return false;
+
+	return true;
+}
+
+static bool
+check_default_with_oids(bool *newval, void **extra, GucSource source)
+{
+	if (*newval)
+	{
+		/* check the GUC's definition for an explanation */
+		GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
+		GUC_check_errmsg("tables declared WITH OIDS are not supported");
+
+		return false;
+	}
+
+	return true;
+}
+
+#include "guc-file.c"
diff --git a/src/backend/utils/misc/help_config.c b/src/backend/utils/misc/help_config.c
new file mode 100644
index 0000000..d97243d
--- /dev/null
+++ b/src/backend/utils/misc/help_config.c
@@ -0,0 +1,137 @@
+/*-------------------------------------------------------------------------
+ * help_config.c
+ *
+ * Displays available options under grand unified configuration scheme
+ *
+ * Options whose flag bits are set to GUC_NO_SHOW_ALL, GUC_NOT_IN_SAMPLE,
+ * or GUC_DISALLOW_IN_FILE are not displayed, unless the user specifically
+ * requests that variable by name
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/help_config.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <limits.h>
+#include <unistd.h>
+
+#include "utils/guc_tables.h"
+#include "utils/help_config.h"
+
+
+/*
+ * This union allows us to mix the numerous different types of structs
+ * that we are organizing.
+ */
+typedef union
+{
+	struct config_generic generic;
+	struct config_bool _bool;
+	struct config_real real;
+	struct config_int integer;
+	struct config_string string;
+	struct config_enum _enum;
+} mixedStruct;
+
+
+static void printMixedStruct(mixedStruct *structToPrint);
+static bool displayStruct(mixedStruct *structToDisplay);
+
+
+void
+GucInfoMain(void)
+{
+	struct config_generic **guc_vars;
+	int			numOpts,
+				i;
+
+	/* Initialize the guc_variables[] array */
+	build_guc_variables();
+
+	guc_vars = get_guc_variables();
+	numOpts = GetNumConfigOptions();
+
+	for (i = 0; i < numOpts; i++)
+	{
+		mixedStruct *var = (mixedStruct *) guc_vars[i];
+
+		if (displayStruct(var))
+			printMixedStruct(var);
+	}
+
+	exit(0);
+}
+
+
+/*
+ * This function will return true if the struct passed to it
+ * should be displayed to the user.
+ */
+static bool
+displayStruct(mixedStruct *structToDisplay)
+{
+	return !(structToDisplay->generic.flags & (GUC_NO_SHOW_ALL |
+											   GUC_NOT_IN_SAMPLE |
+											   GUC_DISALLOW_IN_FILE));
+}
+
+
+/*
+ * This function prints out the generic struct passed to it. It will print out
+ * a different format, depending on what the user wants to see.
+ */
+static void
+printMixedStruct(mixedStruct *structToPrint)
+{
+	printf("%s\t%s\t%s\t",
+		   structToPrint->generic.name,
+		   GucContext_Names[structToPrint->generic.context],
+		   _(config_group_names[structToPrint->generic.group]));
+
+	switch (structToPrint->generic.vartype)
+	{
+
+		case PGC_BOOL:
+			printf("BOOLEAN\t%s\t\t\t",
+				   (structToPrint->_bool.reset_val == 0) ?
+				   "FALSE" : "TRUE");
+			break;
+
+		case PGC_INT:
+			printf("INTEGER\t%d\t%d\t%d\t",
+				   structToPrint->integer.reset_val,
+				   structToPrint->integer.min,
+				   structToPrint->integer.max);
+			break;
+
+		case PGC_REAL:
+			printf("REAL\t%g\t%g\t%g\t",
+				   structToPrint->real.reset_val,
+				   structToPrint->real.min,
+				   structToPrint->real.max);
+			break;
+
+		case PGC_STRING:
+			printf("STRING\t%s\t\t\t",
+				   structToPrint->string.boot_val ? structToPrint->string.boot_val : "");
+			break;
+
+		case PGC_ENUM:
+			printf("ENUM\t%s\t\t\t",
+				   config_enum_lookup_by_value(&structToPrint->_enum,
+											   structToPrint->_enum.boot_val));
+			break;
+
+		default:
+			write_stderr("internal error: unrecognized run-time parameter type\n");
+			break;
+	}
+
+	printf("%s\t%s\n",
+		   (structToPrint->generic.short_desc == NULL) ? "" : _(structToPrint->generic.short_desc),
+		   (structToPrint->generic.long_desc == NULL) ? "" : _(structToPrint->generic.long_desc));
+}
diff --git a/src/backend/utils/misc/pg_config.c b/src/backend/utils/misc/pg_config.c
new file mode 100644
index 0000000..34d77db
--- /dev/null
+++ b/src/backend/utils/misc/pg_config.c
@@ -0,0 +1,102 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_config.c
+ *		Expose same output as pg_config except as an SRF
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/pg_config.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "catalog/pg_type.h"
+#include "common/config_info.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "port.h"
+#include "utils/builtins.h"
+
+Datum
+pg_config(PG_FUNCTION_ARGS)
+{
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Tuplestorestate *tupstore;
+	HeapTuple	tuple;
+	TupleDesc	tupdesc;
+	AttInMetadata *attinmeta;
+	MemoryContext per_query_ctx;
+	MemoryContext oldcontext;
+	ConfigData *configdata;
+	size_t		configdata_len;
+	char	   *values[2];
+	int			i = 0;
+
+	/* check to see if caller supports us returning a tuplestore */
+	if (!rsinfo || !(rsinfo->allowedModes & SFRM_Materialize))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("materialize mode required, but it is not "
+						"allowed in this context")));
+
+	per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
+	oldcontext = MemoryContextSwitchTo(per_query_ctx);
+
+	/* get the requested return tuple description */
+	tupdesc = CreateTupleDescCopy(rsinfo->expectedDesc);
+
+	/*
+	 * Check to make sure we have a reasonable tuple descriptor
+	 */
+	if (tupdesc->natts != 2 ||
+		TupleDescAttr(tupdesc, 0)->atttypid != TEXTOID ||
+		TupleDescAttr(tupdesc, 1)->atttypid != TEXTOID)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("query-specified return tuple and "
+						"function return type are not compatible")));
+
+	/* OK to use it */
+	attinmeta = TupleDescGetAttInMetadata(tupdesc);
+
+	/* let the caller know we're sending back a tuplestore */
+	rsinfo->returnMode = SFRM_Materialize;
+
+	/* initialize our tuplestore */
+	tupstore = tuplestore_begin_heap(true, false, work_mem);
+
+	configdata = get_configdata(my_exec_path, &configdata_len);
+	for (i = 0; i < configdata_len; i++)
+	{
+		values[0] = configdata[i].name;
+		values[1] = configdata[i].setting;
+
+		tuple = BuildTupleFromCStrings(attinmeta, values);
+		tuplestore_puttuple(tupstore, tuple);
+	}
+
+	/*
+	 * no longer need the tuple descriptor reference created by
+	 * TupleDescGetAttInMetadata()
+	 */
+	ReleaseTupleDesc(tupdesc);
+
+	tuplestore_donestoring(tupstore);
+	rsinfo->setResult = tupstore;
+
+	/*
+	 * SFRM_Materialize mode expects us to return a NULL Datum. The actual
+	 * tuples are in our tuplestore and passed back through rsinfo->setResult.
+	 * rsinfo->setDesc is set to the tuple description that we actually used
+	 * to build our tuples with, so the caller can verify we did what it was
+	 * expecting.
+	 */
+	rsinfo->setDesc = tupdesc;
+	MemoryContextSwitchTo(oldcontext);
+
+	return (Datum) 0;
+}
diff --git a/src/backend/utils/misc/pg_controldata.c b/src/backend/utils/misc/pg_controldata.c
new file mode 100644
index 0000000..209a20a
--- /dev/null
+++ b/src/backend/utils/misc/pg_controldata.c
@@ -0,0 +1,344 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_controldata.c
+ *
+ * Routines to expose the contents of the control data file via
+ * a set of SQL functions.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/pg_controldata.c
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/transam.h"
+#include "access/xlog.h"
+#include "access/xlog_internal.h"
+#include "catalog/pg_control.h"
+#include "catalog/pg_type.h"
+#include "common/controldata_utils.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "utils/builtins.h"
+#include "utils/pg_lsn.h"
+#include "utils/timestamp.h"
+
+Datum
+pg_control_system(PG_FUNCTION_ARGS)
+{
+	Datum		values[4];
+	bool		nulls[4];
+	TupleDesc	tupdesc;
+	HeapTuple	htup;
+	ControlFileData *ControlFile;
+	bool		crc_ok;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(4);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pg_control_version",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "catalog_version_no",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "system_identifier",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "pg_control_last_modified",
+					   TIMESTAMPTZOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, &crc_ok);
+	if (!crc_ok)
+		ereport(ERROR,
+				(errmsg("calculated CRC checksum does not match value stored in file")));
+
+	values[0] = Int32GetDatum(ControlFile->pg_control_version);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->catalog_version_no);
+	nulls[1] = false;
+
+	values[2] = Int64GetDatum(ControlFile->system_identifier);
+	nulls[2] = false;
+
+	values[3] = TimestampTzGetDatum(time_t_to_timestamptz(ControlFile->time));
+	nulls[3] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_checkpoint(PG_FUNCTION_ARGS)
+{
+	Datum		values[19];
+	bool		nulls[19];
+	TupleDesc	tupdesc;
+	HeapTuple	htup;
+	ControlFileData *ControlFile;
+	XLogSegNo	segno;
+	char		xlogfilename[MAXFNAMELEN];
+	bool		crc_ok;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(18);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "checkpoint_lsn",
+					   PG_LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "redo_lsn",
+					   PG_LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "redo_wal_file",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "timeline_id",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "prev_timeline_id",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "full_page_writes",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "next_xid",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "next_oid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "next_multixact_id",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "next_multi_offset",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "oldest_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "oldest_xid_dbid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "oldest_active_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "oldest_multi_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 15, "oldest_multi_dbid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 16, "oldest_commit_ts_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 17, "newest_commit_ts_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 18, "checkpoint_time",
+					   TIMESTAMPTZOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* Read the control file. */
+	ControlFile = get_controlfile(DataDir, &crc_ok);
+	if (!crc_ok)
+		ereport(ERROR,
+				(errmsg("calculated CRC checksum does not match value stored in file")));
+
+	/*
+	 * Calculate name of the WAL file containing the latest checkpoint's REDO
+	 * start point.
+	 */
+	XLByteToSeg(ControlFile->checkPointCopy.redo, segno, wal_segment_size);
+	XLogFileName(xlogfilename, ControlFile->checkPointCopy.ThisTimeLineID,
+				 segno, wal_segment_size);
+
+	/* Populate the values and null arrays */
+	values[0] = LSNGetDatum(ControlFile->checkPoint);
+	nulls[0] = false;
+
+	values[1] = LSNGetDatum(ControlFile->checkPointCopy.redo);
+	nulls[1] = false;
+
+	values[2] = CStringGetTextDatum(xlogfilename);
+	nulls[2] = false;
+
+	values[3] = Int32GetDatum(ControlFile->checkPointCopy.ThisTimeLineID);
+	nulls[3] = false;
+
+	values[4] = Int32GetDatum(ControlFile->checkPointCopy.PrevTimeLineID);
+	nulls[4] = false;
+
+	values[5] = BoolGetDatum(ControlFile->checkPointCopy.fullPageWrites);
+	nulls[5] = false;
+
+	values[6] = CStringGetTextDatum(psprintf("%u:%u",
+											 EpochFromFullTransactionId(ControlFile->checkPointCopy.nextXid),
+											 XidFromFullTransactionId(ControlFile->checkPointCopy.nextXid)));
+	nulls[6] = false;
+
+	values[7] = ObjectIdGetDatum(ControlFile->checkPointCopy.nextOid);
+	nulls[7] = false;
+
+	values[8] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMulti);
+	nulls[8] = false;
+
+	values[9] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMultiOffset);
+	nulls[9] = false;
+
+	values[10] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestXid);
+	nulls[10] = false;
+
+	values[11] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestXidDB);
+	nulls[11] = false;
+
+	values[12] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestActiveXid);
+	nulls[12] = false;
+
+	values[13] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestMulti);
+	nulls[13] = false;
+
+	values[14] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestMultiDB);
+	nulls[14] = false;
+
+	values[15] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestCommitTsXid);
+	nulls[15] = false;
+
+	values[16] = TransactionIdGetDatum(ControlFile->checkPointCopy.newestCommitTsXid);
+	nulls[16] = false;
+
+	values[17] = TimestampTzGetDatum(time_t_to_timestamptz(ControlFile->checkPointCopy.time));
+	nulls[17] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_recovery(PG_FUNCTION_ARGS)
+{
+	Datum		values[5];
+	bool		nulls[5];
+	TupleDesc	tupdesc;
+	HeapTuple	htup;
+	ControlFileData *ControlFile;
+	bool		crc_ok;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(5);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "min_recovery_end_lsn",
+					   PG_LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "min_recovery_end_timeline",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "backup_start_lsn",
+					   PG_LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "backup_end_lsn",
+					   PG_LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "end_of_backup_record_required",
+					   BOOLOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, &crc_ok);
+	if (!crc_ok)
+		ereport(ERROR,
+				(errmsg("calculated CRC checksum does not match value stored in file")));
+
+	values[0] = LSNGetDatum(ControlFile->minRecoveryPoint);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->minRecoveryPointTLI);
+	nulls[1] = false;
+
+	values[2] = LSNGetDatum(ControlFile->backupStartPoint);
+	nulls[2] = false;
+
+	values[3] = LSNGetDatum(ControlFile->backupEndPoint);
+	nulls[3] = false;
+
+	values[4] = BoolGetDatum(ControlFile->backupEndRequired);
+	nulls[4] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_init(PG_FUNCTION_ARGS)
+{
+	Datum		values[11];
+	bool		nulls[11];
+	TupleDesc	tupdesc;
+	HeapTuple	htup;
+	ControlFileData *ControlFile;
+	bool		crc_ok;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(11);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "max_data_alignment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "database_block_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "blocks_per_segment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "wal_block_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "bytes_per_wal_segment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "max_identifier_length",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "max_index_columns",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "max_toast_chunk_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "large_object_chunk_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "float8_pass_by_value",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "data_page_checksum_version",
+					   INT4OID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, &crc_ok);
+	if (!crc_ok)
+		ereport(ERROR,
+				(errmsg("calculated CRC checksum does not match value stored in file")));
+
+	values[0] = Int32GetDatum(ControlFile->maxAlign);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->blcksz);
+	nulls[1] = false;
+
+	values[2] = Int32GetDatum(ControlFile->relseg_size);
+	nulls[2] = false;
+
+	values[3] = Int32GetDatum(ControlFile->xlog_blcksz);
+	nulls[3] = false;
+
+	values[4] = Int32GetDatum(ControlFile->xlog_seg_size);
+	nulls[4] = false;
+
+	values[5] = Int32GetDatum(ControlFile->nameDataLen);
+	nulls[5] = false;
+
+	values[6] = Int32GetDatum(ControlFile->indexMaxKeys);
+	nulls[6] = false;
+
+	values[7] = Int32GetDatum(ControlFile->toast_max_chunk_size);
+	nulls[7] = false;
+
+	values[8] = Int32GetDatum(ControlFile->loblksize);
+	nulls[8] = false;
+
+	values[9] = BoolGetDatum(ControlFile->float8ByVal);
+	nulls[9] = false;
+
+	values[10] = Int32GetDatum(ControlFile->data_checksum_version);
+	nulls[10] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
diff --git a/src/backend/utils/misc/pg_rusage.c b/src/backend/utils/misc/pg_rusage.c
new file mode 100644
index 0000000..bb5d9e7
--- /dev/null
+++ b/src/backend/utils/misc/pg_rusage.c
@@ -0,0 +1,73 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_rusage.c
+ *	  Resource usage measurement support routines.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/pg_rusage.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <unistd.h>
+
+#include "utils/pg_rusage.h"
+
+
+/*
+ * Initialize usage snapshot.
+ */
+void
+pg_rusage_init(PGRUsage *ru0)
+{
+	getrusage(RUSAGE_SELF, &ru0->ru);
+	gettimeofday(&ru0->tv, NULL);
+}
+
+/*
+ * Compute elapsed time since ru0 usage snapshot, and format into
+ * a displayable string.  Result is in a static string, which is
+ * tacky, but no one ever claimed that the Postgres backend is
+ * threadable...
+ */
+const char *
+pg_rusage_show(const PGRUsage *ru0)
+{
+	static char result[100];
+	PGRUsage	ru1;
+
+	pg_rusage_init(&ru1);
+
+	if (ru1.tv.tv_usec < ru0->tv.tv_usec)
+	{
+		ru1.tv.tv_sec--;
+		ru1.tv.tv_usec += 1000000;
+	}
+	if (ru1.ru.ru_stime.tv_usec < ru0->ru.ru_stime.tv_usec)
+	{
+		ru1.ru.ru_stime.tv_sec--;
+		ru1.ru.ru_stime.tv_usec += 1000000;
+	}
+	if (ru1.ru.ru_utime.tv_usec < ru0->ru.ru_utime.tv_usec)
+	{
+		ru1.ru.ru_utime.tv_sec--;
+		ru1.ru.ru_utime.tv_usec += 1000000;
+	}
+
+	snprintf(result, sizeof(result),
+			 _("CPU: user: %d.%02d s, system: %d.%02d s, elapsed: %d.%02d s"),
+			 (int) (ru1.ru.ru_utime.tv_sec - ru0->ru.ru_utime.tv_sec),
+			 (int) (ru1.ru.ru_utime.tv_usec - ru0->ru.ru_utime.tv_usec) / 10000,
+			 (int) (ru1.ru.ru_stime.tv_sec - ru0->ru.ru_stime.tv_sec),
+			 (int) (ru1.ru.ru_stime.tv_usec - ru0->ru.ru_stime.tv_usec) / 10000,
+			 (int) (ru1.tv.tv_sec - ru0->tv.tv_sec),
+			 (int) (ru1.tv.tv_usec - ru0->tv.tv_usec) / 10000);
+
+	return result;
+}
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
new file mode 100644
index 0000000..4557ba7
--- /dev/null
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -0,0 +1,796 @@
+# -----------------------------
+# PostgreSQL configuration file
+# -----------------------------
+#
+# This file consists of lines of the form:
+#
+#   name = value
+#
+# (The "=" is optional.)  Whitespace may be used.  Comments are introduced with
+# "#" anywhere on a line.  The complete list of parameter names and allowed
+# values can be found in the PostgreSQL documentation.
+#
+# The commented-out settings shown in this file represent the default values.
+# Re-commenting a setting is NOT sufficient to revert it to the default value;
+# you need to reload the server.
+#
+# This file is read on server startup and when the server receives a SIGHUP
+# signal.  If you edit the file on a running system, you have to SIGHUP the
+# server for the changes to take effect, run "pg_ctl reload", or execute
+# "SELECT pg_reload_conf()".  Some parameters, which are marked below,
+# require a server shutdown and restart to take effect.
+#
+# Any parameter can also be given as a command-line option to the server, e.g.,
+# "postgres -c log_connections=on".  Some parameters can be changed at run time
+# with the "SET" SQL command.
+#
+# Memory units:  B  = bytes            Time units:  us  = microseconds
+#                kB = kilobytes                     ms  = milliseconds
+#                MB = megabytes                     s   = seconds
+#                GB = gigabytes                     min = minutes
+#                TB = terabytes                     h   = hours
+#                                                   d   = days
+
+
+#------------------------------------------------------------------------------
+# FILE LOCATIONS
+#------------------------------------------------------------------------------
+
+# The default values of these variables are driven from the -D command-line
+# option or PGDATA environment variable, represented here as ConfigDir.
+
+#data_directory = 'ConfigDir'		# use data in another directory
+					# (change requires restart)
+#hba_file = 'ConfigDir/pg_hba.conf'	# host-based authentication file
+					# (change requires restart)
+#ident_file = 'ConfigDir/pg_ident.conf'	# ident configuration file
+					# (change requires restart)
+
+# If external_pid_file is not explicitly set, no extra PID file is written.
+#external_pid_file = ''			# write an extra PID file
+					# (change requires restart)
+
+
+#------------------------------------------------------------------------------
+# CONNECTIONS AND AUTHENTICATION
+#------------------------------------------------------------------------------
+
+# - Connection Settings -
+
+#listen_addresses = 'localhost'		# what IP address(es) to listen on;
+					# comma-separated list of addresses;
+					# defaults to 'localhost'; use '*' for all
+					# (change requires restart)
+#port = 5432				# (change requires restart)
+#max_connections = 100			# (change requires restart)
+#superuser_reserved_connections = 3	# (change requires restart)
+#unix_socket_directories = '/tmp'	# comma-separated list of directories
+					# (change requires restart)
+#unix_socket_group = ''			# (change requires restart)
+#unix_socket_permissions = 0777		# begin with 0 to use octal notation
+					# (change requires restart)
+#bonjour = off				# advertise server via Bonjour
+					# (change requires restart)
+#bonjour_name = ''			# defaults to the computer name
+					# (change requires restart)
+
+# - TCP settings -
+# see "man tcp" for details
+
+#tcp_keepalives_idle = 0		# TCP_KEEPIDLE, in seconds;
+					# 0 selects the system default
+#tcp_keepalives_interval = 0		# TCP_KEEPINTVL, in seconds;
+					# 0 selects the system default
+#tcp_keepalives_count = 0		# TCP_KEEPCNT;
+					# 0 selects the system default
+#tcp_user_timeout = 0			# TCP_USER_TIMEOUT, in milliseconds;
+					# 0 selects the system default
+
+#client_connection_check_interval = 0	# time between checks for client
+					# disconnection while running queries;
+					# 0 for never
+
+# - Authentication -
+
+#authentication_timeout = 1min		# 1s-600s
+#password_encryption = scram-sha-256	# scram-sha-256 or md5
+#db_user_namespace = off
+
+# GSSAPI using Kerberos
+#krb_server_keyfile = 'FILE:${sysconfdir}/krb5.keytab'
+#krb_caseins_users = off
+
+# - SSL -
+
+#ssl = off
+#ssl_ca_file = ''
+#ssl_cert_file = 'server.crt'
+#ssl_crl_file = ''
+#ssl_crl_dir = ''
+#ssl_key_file = 'server.key'
+#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
+#ssl_prefer_server_ciphers = on
+#ssl_ecdh_curve = 'prime256v1'
+#ssl_min_protocol_version = 'TLSv1.2'
+#ssl_max_protocol_version = ''
+#ssl_dh_params_file = ''
+#ssl_passphrase_command = ''
+#ssl_passphrase_command_supports_reload = off
+
+
+#------------------------------------------------------------------------------
+# RESOURCE USAGE (except WAL)
+#------------------------------------------------------------------------------
+
+# - Memory -
+
+#shared_buffers = 32MB			# min 128kB
+					# (change requires restart)
+#huge_pages = try			# on, off, or try
+					# (change requires restart)
+#huge_page_size = 0			# zero for system default
+					# (change requires restart)
+#temp_buffers = 8MB			# min 800kB
+#max_prepared_transactions = 0		# zero disables the feature
+					# (change requires restart)
+# Caution: it is not advisable to set max_prepared_transactions nonzero unless
+# you actively intend to use prepared transactions.
+#work_mem = 4MB				# min 64kB
+#hash_mem_multiplier = 1.0		# 1-1000.0 multiplier on hash table work_mem
+#maintenance_work_mem = 64MB		# min 1MB
+#autovacuum_work_mem = -1		# min 1MB, or -1 to use maintenance_work_mem
+#logical_decoding_work_mem = 64MB	# min 64kB
+#max_stack_depth = 2MB			# min 100kB
+#shared_memory_type = mmap		# the default is the first option
+					# supported by the operating system:
+					#   mmap
+					#   sysv
+					#   windows
+					# (change requires restart)
+#dynamic_shared_memory_type = posix	# the default is the first option
+					# supported by the operating system:
+					#   posix
+					#   sysv
+					#   windows
+					#   mmap
+					# (change requires restart)
+#min_dynamic_shared_memory = 0MB	# (change requires restart)
+
+# - Disk -
+
+#temp_file_limit = -1			# limits per-process temp file space
+					# in kilobytes, or -1 for no limit
+
+# - Kernel Resources -
+
+#max_files_per_process = 1000		# min 64
+					# (change requires restart)
+
+# - Cost-Based Vacuum Delay -
+
+#vacuum_cost_delay = 0			# 0-100 milliseconds (0 disables)
+#vacuum_cost_page_hit = 1		# 0-10000 credits
+#vacuum_cost_page_miss = 2		# 0-10000 credits
+#vacuum_cost_page_dirty = 20		# 0-10000 credits
+#vacuum_cost_limit = 200		# 1-10000 credits
+
+# - Background Writer -
+
+#bgwriter_delay = 200ms			# 10-10000ms between rounds
+#bgwriter_lru_maxpages = 100		# max buffers written/round, 0 disables
+#bgwriter_lru_multiplier = 2.0		# 0-10.0 multiplier on buffers scanned/round
+#bgwriter_flush_after = 0		# measured in pages, 0 disables
+
+# - Asynchronous Behavior -
+
+#backend_flush_after = 0		# measured in pages, 0 disables
+#effective_io_concurrency = 1		# 1-1000; 0 disables prefetching
+#maintenance_io_concurrency = 10	# 1-1000; 0 disables prefetching
+#max_worker_processes = 8		# (change requires restart)
+#max_parallel_workers_per_gather = 2	# taken from max_parallel_workers
+#max_parallel_maintenance_workers = 2	# taken from max_parallel_workers
+#max_parallel_workers = 8		# maximum number of max_worker_processes that
+					# can be used in parallel operations
+#parallel_leader_participation = on
+#old_snapshot_threshold = -1		# 1min-60d; -1 disables; 0 is immediate
+					# (change requires restart)
+
+
+#------------------------------------------------------------------------------
+# WRITE-AHEAD LOG
+#------------------------------------------------------------------------------
+
+# - Settings -
+
+#wal_level = replica			# minimal, replica, or logical
+					# (change requires restart)
+#fsync = on				# flush data to disk for crash safety
+					# (turning this off can cause
+					# unrecoverable data corruption)
+#synchronous_commit = on		# synchronization level;
+					# off, local, remote_write, remote_apply, or on
+#wal_sync_method = fsync		# the default is the first option
+					# supported by the operating system:
+					#   open_datasync
+					#   fdatasync (default on Linux and FreeBSD)
+					#   fsync
+					#   fsync_writethrough
+					#   open_sync
+#full_page_writes = on			# recover from partial page writes
+#wal_log_hints = off			# also do full page writes of non-critical updates
+					# (change requires restart)
+#wal_compression = off			# enable compression of full-page writes
+#wal_init_zero = on			# zero-fill new WAL files
+#wal_recycle = on			# recycle WAL files
+#wal_buffers = -1			# min 32kB, -1 sets based on shared_buffers
+					# (change requires restart)
+#wal_writer_delay = 200ms		# 1-10000 milliseconds
+#wal_writer_flush_after = 1MB		# measured in pages, 0 disables
+#wal_skip_threshold = 2MB
+
+#commit_delay = 0			# range 0-100000, in microseconds
+#commit_siblings = 5			# range 1-1000
+
+# - Checkpoints -
+
+#checkpoint_timeout = 5min		# range 30s-1d
+#checkpoint_completion_target = 0.9	# checkpoint target duration, 0.0 - 1.0
+#checkpoint_flush_after = 0		# measured in pages, 0 disables
+#checkpoint_warning = 30s		# 0 disables
+#max_wal_size = 1GB
+#min_wal_size = 80MB
+
+# - Archiving -
+
+#archive_mode = off		# enables archiving; off, on, or always
+				# (change requires restart)
+#archive_command = ''		# command to use to archive a logfile segment
+				# placeholders: %p = path of file to archive
+				#               %f = file name only
+				# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
+#archive_timeout = 0		# force a logfile segment switch after this
+				# number of seconds; 0 disables
+
+# - Archive Recovery -
+
+# These are only used in recovery mode.
+
+#restore_command = ''		# command to use to restore an archived logfile segment
+				# placeholders: %p = path of file to restore
+				#               %f = file name only
+				# e.g. 'cp /mnt/server/archivedir/%f %p'
+#archive_cleanup_command = ''	# command to execute at every restartpoint
+#recovery_end_command = ''	# command to execute at completion of recovery
+
+# - Recovery Target -
+
+# Set these only when performing a targeted recovery.
+
+#recovery_target = ''		# 'immediate' to end recovery as soon as a
+                                # consistent state is reached
+				# (change requires restart)
+#recovery_target_name = ''	# the named restore point to which recovery will proceed
+				# (change requires restart)
+#recovery_target_time = ''	# the time stamp up to which recovery will proceed
+				# (change requires restart)
+#recovery_target_xid = ''	# the transaction ID up to which recovery will proceed
+				# (change requires restart)
+#recovery_target_lsn = ''	# the WAL LSN up to which recovery will proceed
+				# (change requires restart)
+#recovery_target_inclusive = on # Specifies whether to stop:
+				# just after the specified recovery target (on)
+				# just before the recovery target (off)
+				# (change requires restart)
+#recovery_target_timeline = 'latest'	# 'current', 'latest', or timeline ID
+				# (change requires restart)
+#recovery_target_action = 'pause'	# 'pause', 'promote', 'shutdown'
+				# (change requires restart)
+
+
+#------------------------------------------------------------------------------
+# REPLICATION
+#------------------------------------------------------------------------------
+
+# - Sending Servers -
+
+# Set these on the primary and on any standby that will send replication data.
+
+#max_wal_senders = 10		# max number of walsender processes
+				# (change requires restart)
+#max_replication_slots = 10	# max number of replication slots
+				# (change requires restart)
+#wal_keep_size = 0		# in megabytes; 0 disables
+#max_slot_wal_keep_size = -1	# in megabytes; -1 disables
+#wal_sender_timeout = 60s	# in milliseconds; 0 disables
+#track_commit_timestamp = off	# collect timestamp of transaction commit
+				# (change requires restart)
+
+# - Primary Server -
+
+# These settings are ignored on a standby server.
+
+#synchronous_standby_names = ''	# standby servers that provide sync rep
+				# method to choose sync standbys, number of sync standbys,
+				# and comma-separated list of application_name
+				# from standby(s); '*' = all
+#vacuum_defer_cleanup_age = 0	# number of xacts by which cleanup is delayed
+
+# - Standby Servers -
+
+# These settings are ignored on a primary server.
+
+#primary_conninfo = ''			# connection string to sending server
+#primary_slot_name = ''			# replication slot on sending server
+#promote_trigger_file = ''		# file name whose presence ends recovery
+#hot_standby = on			# "off" disallows queries during recovery
+					# (change requires restart)
+#max_standby_archive_delay = 30s	# max delay before canceling queries
+					# when reading WAL from archive;
+					# -1 allows indefinite delay
+#max_standby_streaming_delay = 30s	# max delay before canceling queries
+					# when reading streaming WAL;
+					# -1 allows indefinite delay
+#wal_receiver_create_temp_slot = off	# create temp slot if primary_slot_name
+					# is not set
+#wal_receiver_status_interval = 10s	# send replies at least this often
+					# 0 disables
+#hot_standby_feedback = off		# send info from standby to prevent
+					# query conflicts
+#wal_receiver_timeout = 60s		# time that receiver waits for
+					# communication from primary
+					# in milliseconds; 0 disables
+#wal_retrieve_retry_interval = 5s	# time to wait before retrying to
+					# retrieve WAL after a failed attempt
+#recovery_min_apply_delay = 0		# minimum delay for applying changes during recovery
+
+# - Subscribers -
+
+# These settings are ignored on a publisher.
+
+#max_logical_replication_workers = 4	# taken from max_worker_processes
+					# (change requires restart)
+#max_sync_workers_per_subscription = 2	# taken from max_logical_replication_workers
+
+
+#------------------------------------------------------------------------------
+# QUERY TUNING
+#------------------------------------------------------------------------------
+
+# - Planner Method Configuration -
+
+#enable_async_append = on
+#enable_bitmapscan = on
+#enable_gathermerge = on
+#enable_hashagg = on
+#enable_hashjoin = on
+#enable_incremental_sort = on
+#enable_indexscan = on
+#enable_indexonlyscan = on
+#enable_material = on
+#enable_memoize = on
+#enable_mergejoin = on
+#enable_nestloop = on
+#enable_parallel_append = on
+#enable_parallel_hash = on
+#enable_partition_pruning = on
+#enable_partitionwise_join = off
+#enable_partitionwise_aggregate = off
+#enable_seqscan = on
+#enable_sort = on
+#enable_tidscan = on
+
+# - Planner Cost Constants -
+
+#seq_page_cost = 1.0			# measured on an arbitrary scale
+#random_page_cost = 4.0			# same scale as above
+#cpu_tuple_cost = 0.01			# same scale as above
+#cpu_index_tuple_cost = 0.005		# same scale as above
+#cpu_operator_cost = 0.0025		# same scale as above
+#parallel_setup_cost = 1000.0	# same scale as above
+#parallel_tuple_cost = 0.1		# same scale as above
+#min_parallel_table_scan_size = 8MB
+#min_parallel_index_scan_size = 512kB
+#effective_cache_size = 4GB
+
+#jit_above_cost = 100000		# perform JIT compilation if available
+					# and query more expensive than this;
+					# -1 disables
+#jit_inline_above_cost = 500000		# inline small functions if query is
+					# more expensive than this; -1 disables
+#jit_optimize_above_cost = 500000	# use expensive JIT optimizations if
+					# query is more expensive than this;
+					# -1 disables
+
+# - Genetic Query Optimizer -
+
+#geqo = on
+#geqo_threshold = 12
+#geqo_effort = 5			# range 1-10
+#geqo_pool_size = 0			# selects default based on effort
+#geqo_generations = 0			# selects default based on effort
+#geqo_selection_bias = 2.0		# range 1.5-2.0
+#geqo_seed = 0.0			# range 0.0-1.0
+
+# - Other Planner Options -
+
+#default_statistics_target = 100	# range 1-10000
+#constraint_exclusion = partition	# on, off, or partition
+#cursor_tuple_fraction = 0.1		# range 0.0-1.0
+#from_collapse_limit = 8
+#jit = on				# allow JIT compilation
+#join_collapse_limit = 8		# 1 disables collapsing of explicit
+					# JOIN clauses
+#plan_cache_mode = auto			# auto, force_generic_plan or
+					# force_custom_plan
+
+
+#------------------------------------------------------------------------------
+# REPORTING AND LOGGING
+#------------------------------------------------------------------------------
+
+# - Where to Log -
+
+#log_destination = 'stderr'		# Valid values are combinations of
+					# stderr, csvlog, syslog, and eventlog,
+					# depending on platform.  csvlog
+					# requires logging_collector to be on.
+
+# This is used when logging to stderr:
+#logging_collector = off		# Enable capturing of stderr and csvlog
+					# into log files. Required to be on for
+					# csvlogs.
+					# (change requires restart)
+
+# These are only used if logging_collector is on:
+#log_directory = 'log'			# directory where log files are written,
+					# can be absolute or relative to PGDATA
+#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'	# log file name pattern,
+					# can include strftime() escapes
+#log_file_mode = 0600			# creation mode for log files,
+					# begin with 0 to use octal notation
+#log_rotation_age = 1d			# Automatic rotation of logfiles will
+					# happen after that time.  0 disables.
+#log_rotation_size = 10MB		# Automatic rotation of logfiles will
+					# happen after that much log output.
+					# 0 disables.
+#log_truncate_on_rotation = off		# If on, an existing log file with the
+					# same name as the new log file will be
+					# truncated rather than appended to.
+					# But such truncation only occurs on
+					# time-driven rotation, not on restarts
+					# or size-driven rotation.  Default is
+					# off, meaning append to existing files
+					# in all cases.
+
+# These are relevant when logging to syslog:
+#syslog_facility = 'LOCAL0'
+#syslog_ident = 'postgres'
+#syslog_sequence_numbers = on
+#syslog_split_messages = on
+
+# This is only relevant when logging to eventlog (Windows):
+# (change requires restart)
+#event_source = 'PostgreSQL'
+
+# - When to Log -
+
+#log_min_messages = warning		# values in order of decreasing detail:
+					#   debug5
+					#   debug4
+					#   debug3
+					#   debug2
+					#   debug1
+					#   info
+					#   notice
+					#   warning
+					#   error
+					#   log
+					#   fatal
+					#   panic
+
+#log_min_error_statement = error	# values in order of decreasing detail:
+					#   debug5
+					#   debug4
+					#   debug3
+					#   debug2
+					#   debug1
+					#   info
+					#   notice
+					#   warning
+					#   error
+					#   log
+					#   fatal
+					#   panic (effectively off)
+
+#log_min_duration_statement = -1	# -1 is disabled, 0 logs all statements
+					# and their durations, > 0 logs only
+					# statements running at least this number
+					# of milliseconds
+
+#log_min_duration_sample = -1		# -1 is disabled, 0 logs a sample of statements
+					# and their durations, > 0 logs only a sample of
+					# statements running at least this number
+					# of milliseconds;
+					# sample fraction is determined by log_statement_sample_rate
+
+#log_statement_sample_rate = 1.0	# fraction of logged statements exceeding
+					# log_min_duration_sample to be logged;
+					# 1.0 logs all such statements, 0.0 never logs
+
+
+#log_transaction_sample_rate = 0.0	# fraction of transactions whose statements
+					# are logged regardless of their duration; 1.0 logs all
+					# statements from all transactions, 0.0 never logs
+
+# - What to Log -
+
+#debug_print_parse = off
+#debug_print_rewritten = off
+#debug_print_plan = off
+#debug_pretty_print = on
+#log_autovacuum_min_duration = -1	# log autovacuum activity;
+					# -1 disables, 0 logs all actions and
+					# their durations, > 0 logs only
+					# actions running at least this number
+					# of milliseconds.
+#log_checkpoints = off
+#log_connections = off
+#log_disconnections = off
+#log_duration = off
+#log_error_verbosity = default		# terse, default, or verbose messages
+#log_hostname = off
+#log_line_prefix = '%m [%p] '		# special values:
+					#   %a = application name
+					#   %u = user name
+					#   %d = database name
+					#   %r = remote host and port
+					#   %h = remote host
+					#   %b = backend type
+					#   %p = process ID
+					#   %P = process ID of parallel group leader
+					#   %t = timestamp without milliseconds
+					#   %m = timestamp with milliseconds
+					#   %n = timestamp with milliseconds (as a Unix epoch)
+					#   %Q = query ID (0 if none or not computed)
+					#   %i = command tag
+					#   %e = SQL state
+					#   %c = session ID
+					#   %l = session line number
+					#   %s = session start timestamp
+					#   %v = virtual transaction ID
+					#   %x = transaction ID (0 if none)
+					#   %q = stop here in non-session
+					#        processes
+					#   %% = '%'
+					# e.g. '<%u%%%d> '
+#log_lock_waits = off			# log lock waits >= deadlock_timeout
+#log_recovery_conflict_waits = off	# log standby recovery conflict waits
+					# >= deadlock_timeout
+#log_parameter_max_length = -1		# when logging statements, limit logged
+					# bind-parameter values to N bytes;
+					# -1 means print in full, 0 disables
+#log_parameter_max_length_on_error = 0	# when logging an error, limit logged
+					# bind-parameter values to N bytes;
+					# -1 means print in full, 0 disables
+#log_statement = 'none'			# none, ddl, mod, all
+#log_replication_commands = off
+#log_temp_files = -1			# log temporary files equal or larger
+					# than the specified size in kilobytes;
+					# -1 disables, 0 logs all temp files
+#log_timezone = 'GMT'
+
+
+#------------------------------------------------------------------------------
+# PROCESS TITLE
+#------------------------------------------------------------------------------
+
+#cluster_name = ''			# added to process titles if nonempty
+					# (change requires restart)
+#update_process_title = on
+
+
+#------------------------------------------------------------------------------
+# STATISTICS
+#------------------------------------------------------------------------------
+
+# - Query and Index Statistics Collector -
+
+#track_activities = on
+#track_activity_query_size = 1024	# (change requires restart)
+#track_counts = on
+#track_io_timing = off
+#track_wal_io_timing = off
+#track_functions = none			# none, pl, all
+#stats_temp_directory = 'pg_stat_tmp'
+
+
+# - Monitoring -
+
+#compute_query_id = auto
+#log_statement_stats = off
+#log_parser_stats = off
+#log_planner_stats = off
+#log_executor_stats = off
+
+
+#------------------------------------------------------------------------------
+# AUTOVACUUM
+#------------------------------------------------------------------------------
+
+#autovacuum = on			# Enable autovacuum subprocess?  'on'
+					# requires track_counts to also be on.
+#autovacuum_max_workers = 3		# max number of autovacuum subprocesses
+					# (change requires restart)
+#autovacuum_naptime = 1min		# time between autovacuum runs
+#autovacuum_vacuum_threshold = 50	# min number of row updates before
+					# vacuum
+#autovacuum_vacuum_insert_threshold = 1000	# min number of row inserts
+					# before vacuum; -1 disables insert
+					# vacuums
+#autovacuum_analyze_threshold = 50	# min number of row updates before
+					# analyze
+#autovacuum_vacuum_scale_factor = 0.2	# fraction of table size before vacuum
+#autovacuum_vacuum_insert_scale_factor = 0.2	# fraction of inserts over table
+					# size before insert vacuum
+#autovacuum_analyze_scale_factor = 0.1	# fraction of table size before analyze
+#autovacuum_freeze_max_age = 200000000	# maximum XID age before forced vacuum
+					# (change requires restart)
+#autovacuum_multixact_freeze_max_age = 400000000	# maximum multixact age
+					# before forced vacuum
+					# (change requires restart)
+#autovacuum_vacuum_cost_delay = 2ms	# default vacuum cost delay for
+					# autovacuum, in milliseconds;
+					# -1 means use vacuum_cost_delay
+#autovacuum_vacuum_cost_limit = -1	# default vacuum cost limit for
+					# autovacuum, -1 means use
+					# vacuum_cost_limit
+
+
+#------------------------------------------------------------------------------
+# CLIENT CONNECTION DEFAULTS
+#------------------------------------------------------------------------------
+
+# - Statement Behavior -
+
+#client_min_messages = notice		# values in order of decreasing detail:
+					#   debug5
+					#   debug4
+					#   debug3
+					#   debug2
+					#   debug1
+					#   log
+					#   notice
+					#   warning
+					#   error
+#search_path = '"$user", public'	# schema names
+#row_security = on
+#default_table_access_method = 'heap'
+#default_tablespace = ''		# a tablespace name, '' uses the default
+#default_toast_compression = 'pglz'	# 'pglz' or 'lz4'
+#temp_tablespaces = ''			# a list of tablespace names, '' uses
+					# only default tablespace
+#check_function_bodies = on
+#default_transaction_isolation = 'read committed'
+#default_transaction_read_only = off
+#default_transaction_deferrable = off
+#session_replication_role = 'origin'
+#statement_timeout = 0			# in milliseconds, 0 is disabled
+#lock_timeout = 0			# in milliseconds, 0 is disabled
+#idle_in_transaction_session_timeout = 0	# in milliseconds, 0 is disabled
+#idle_session_timeout = 0		# in milliseconds, 0 is disabled
+#vacuum_freeze_table_age = 150000000
+#vacuum_freeze_min_age = 50000000
+#vacuum_failsafe_age = 1600000000
+#vacuum_multixact_freeze_table_age = 150000000
+#vacuum_multixact_freeze_min_age = 5000000
+#vacuum_multixact_failsafe_age = 1600000000
+#bytea_output = 'hex'			# hex, escape
+#xmlbinary = 'base64'
+#xmloption = 'content'
+#gin_pending_list_limit = 4MB
+
+# - Locale and Formatting -
+
+#datestyle = 'iso, mdy'
+#intervalstyle = 'postgres'
+#timezone = 'GMT'
+#timezone_abbreviations = 'Default'     # Select the set of available time zone
+					# abbreviations.  Currently, there are
+					#   Default
+					#   Australia (historical usage)
+					#   India
+					# You can create your own file in
+					# share/timezonesets/.
+#extra_float_digits = 1			# min -15, max 3; any value >0 actually
+					# selects precise output mode
+#client_encoding = sql_ascii		# actually, defaults to database
+					# encoding
+
+# These settings are initialized by initdb, but they can be changed.
+#lc_messages = 'C'			# locale for system error message
+					# strings
+#lc_monetary = 'C'			# locale for monetary formatting
+#lc_numeric = 'C'			# locale for number formatting
+#lc_time = 'C'				# locale for time formatting
+
+# default configuration for text search
+#default_text_search_config = 'pg_catalog.simple'
+
+# - Shared Library Preloading -
+
+#local_preload_libraries = ''
+#session_preload_libraries = ''
+#shared_preload_libraries = ''	# (change requires restart)
+#jit_provider = 'llvmjit'		# JIT library to use
+
+# - Other Defaults -
+
+#dynamic_library_path = '$libdir'
+#gin_fuzzy_search_limit = 0
+
+
+#------------------------------------------------------------------------------
+# LOCK MANAGEMENT
+#------------------------------------------------------------------------------
+
+#deadlock_timeout = 1s
+#max_locks_per_transaction = 64		# min 10
+					# (change requires restart)
+#max_pred_locks_per_transaction = 64	# min 10
+					# (change requires restart)
+#max_pred_locks_per_relation = -2	# negative values mean
+					# (max_pred_locks_per_transaction
+					#  / -max_pred_locks_per_relation) - 1
+#max_pred_locks_per_page = 2            # min 0
+
+
+#------------------------------------------------------------------------------
+# VERSION AND PLATFORM COMPATIBILITY
+#------------------------------------------------------------------------------
+
+# - Previous PostgreSQL Versions -
+
+#array_nulls = on
+#backslash_quote = safe_encoding	# on, off, or safe_encoding
+#escape_string_warning = on
+#lo_compat_privileges = off
+#quote_all_identifiers = off
+#standard_conforming_strings = on
+#synchronize_seqscans = on
+
+# - Other Platforms and Clients -
+
+#transform_null_equals = off
+
+
+#------------------------------------------------------------------------------
+# ERROR HANDLING
+#------------------------------------------------------------------------------
+
+#exit_on_error = off			# terminate session on any error?
+#restart_after_crash = on		# reinitialize after backend crash?
+#data_sync_retry = off			# retry or panic on failure to fsync
+					# data?
+					# (change requires restart)
+#recovery_init_sync_method = fsync	# fsync, syncfs (Linux 5.8+)
+
+
+#------------------------------------------------------------------------------
+# CONFIG FILE INCLUDES
+#------------------------------------------------------------------------------
+
+# These options allow settings to be loaded from files other than the
+# default postgresql.conf.  Note that these are directives, not variable
+# assignments, so they can usefully be given more than once.
+
+#include_dir = '...'			# include files ending in '.conf' from
+					# a directory, e.g., 'conf.d'
+#include_if_exists = '...'		# include file only if it exists
+#include = '...'			# include file
+
+
+#------------------------------------------------------------------------------
+# CUSTOMIZED OPTIONS
+#------------------------------------------------------------------------------
+
+# Add settings for extensions here
diff --git a/src/backend/utils/misc/ps_status.c b/src/backend/utils/misc/ps_status.c
new file mode 100644
index 0000000..bad8afb
--- /dev/null
+++ b/src/backend/utils/misc/ps_status.c
@@ -0,0 +1,449 @@
+/*--------------------------------------------------------------------
+ * ps_status.c
+ *
+ * Routines to support changing the ps display of PostgreSQL backends
+ * to contain some useful information. Mechanism differs wildly across
+ * platforms.
+ *
+ * src/backend/utils/misc/ps_status.c
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ * various details abducted from various places
+ *--------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <unistd.h>
+#ifdef HAVE_SYS_PSTAT_H
+#include <sys/pstat.h>			/* for HP-UX */
+#endif
+#ifdef HAVE_PS_STRINGS
+#include <machine/vmparam.h>	/* for old BSD */
+#include <sys/exec.h>
+#endif
+#if defined(__darwin__)
+#include <crt_externs.h>
+#endif
+
+#include "libpq/libpq.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "utils/guc.h"
+#include "utils/ps_status.h"
+
+extern char **environ;
+bool		update_process_title = true;
+
+
+/*
+ * Alternative ways of updating ps display:
+ *
+ * PS_USE_SETPROCTITLE_FAST
+ *	   use the function setproctitle_fast(const char *, ...)
+ *	   (newer FreeBSD systems)
+ * PS_USE_SETPROCTITLE
+ *	   use the function setproctitle(const char *, ...)
+ *	   (newer BSD systems)
+ * PS_USE_PSTAT
+ *	   use the pstat(PSTAT_SETCMD, )
+ *	   (HPUX)
+ * PS_USE_PS_STRINGS
+ *	   assign PS_STRINGS->ps_argvstr = "string"
+ *	   (some BSD systems)
+ * PS_USE_CHANGE_ARGV
+ *	   assign argv[0] = "string"
+ *	   (some other BSD systems)
+ * PS_USE_CLOBBER_ARGV
+ *	   write over the argv and environment area
+ *	   (Linux and most SysV-like systems)
+ * PS_USE_WIN32
+ *	   push the string out as the name of a Windows event
+ * PS_USE_NONE
+ *	   don't update ps display
+ *	   (This is the default, as it is safest.)
+ */
+#if defined(HAVE_SETPROCTITLE_FAST)
+#define PS_USE_SETPROCTITLE_FAST
+#elif defined(HAVE_SETPROCTITLE)
+#define PS_USE_SETPROCTITLE
+#elif defined(HAVE_PSTAT) && defined(PSTAT_SETCMD)
+#define PS_USE_PSTAT
+#elif defined(HAVE_PS_STRINGS)
+#define PS_USE_PS_STRINGS
+#elif (defined(BSD) || defined(__hurd__)) && !defined(__darwin__)
+#define PS_USE_CHANGE_ARGV
+#elif defined(__linux__) || defined(_AIX) || defined(__sgi) || (defined(sun) && !defined(BSD)) || defined(__svr5__) || defined(__darwin__)
+#define PS_USE_CLOBBER_ARGV
+#elif defined(WIN32)
+#define PS_USE_WIN32
+#else
+#define PS_USE_NONE
+#endif
+
+
+/* Different systems want the buffer padded differently */
+#if defined(_AIX) || defined(__linux__) || defined(__darwin__)
+#define PS_PADDING '\0'
+#else
+#define PS_PADDING ' '
+#endif
+
+
+#ifndef PS_USE_NONE
+
+#ifndef PS_USE_CLOBBER_ARGV
+/* all but one option need a buffer to write their ps line in */
+#define PS_BUFFER_SIZE 256
+static char ps_buffer[PS_BUFFER_SIZE];
+static const size_t ps_buffer_size = PS_BUFFER_SIZE;
+#else							/* PS_USE_CLOBBER_ARGV */
+static char *ps_buffer;			/* will point to argv area */
+static size_t ps_buffer_size;	/* space determined at run time */
+static size_t last_status_len;	/* use to minimize length of clobber */
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+static size_t ps_buffer_cur_len;	/* nominal strlen(ps_buffer) */
+
+static size_t ps_buffer_fixed_size; /* size of the constant prefix */
+
+#endif							/* not PS_USE_NONE */
+
+/* save the original argv[] location here */
+static int	save_argc;
+static char **save_argv;
+
+
+/*
+ * Call this early in startup to save the original argc/argv values.
+ * If needed, we make a copy of the original argv[] array to preserve it
+ * from being clobbered by subsequent ps_display actions.
+ *
+ * (The original argv[] will not be overwritten by this routine, but may be
+ * overwritten during init_ps_display.  Also, the physical location of the
+ * environment strings may be moved, so this should be called before any code
+ * that might try to hang onto a getenv() result.)
+ *
+ * Note that in case of failure this cannot call elog() as that is not
+ * initialized yet.  We rely on write_stderr() instead.
+ */
+char	  **
+save_ps_display_args(int argc, char **argv)
+{
+	save_argc = argc;
+	save_argv = argv;
+
+#if defined(PS_USE_CLOBBER_ARGV)
+
+	/*
+	 * If we're going to overwrite the argv area, count the available space.
+	 * Also move the environment to make additional room.
+	 */
+	{
+		char	   *end_of_area = NULL;
+		char	  **new_environ;
+		int			i;
+
+		/*
+		 * check for contiguous argv strings
+		 */
+		for (i = 0; i < argc; i++)
+		{
+			if (i == 0 || end_of_area + 1 == argv[i])
+				end_of_area = argv[i] + strlen(argv[i]);
+		}
+
+		if (end_of_area == NULL)	/* probably can't happen? */
+		{
+			ps_buffer = NULL;
+			ps_buffer_size = 0;
+			return argv;
+		}
+
+		/*
+		 * check for contiguous environ strings following argv
+		 */
+		for (i = 0; environ[i] != NULL; i++)
+		{
+			if (end_of_area + 1 == environ[i])
+				end_of_area = environ[i] + strlen(environ[i]);
+		}
+
+		ps_buffer = argv[0];
+		last_status_len = ps_buffer_size = end_of_area - argv[0];
+
+		/*
+		 * move the environment out of the way
+		 */
+		new_environ = (char **) malloc((i + 1) * sizeof(char *));
+		if (!new_environ)
+		{
+			write_stderr("out of memory\n");
+			exit(1);
+		}
+		for (i = 0; environ[i] != NULL; i++)
+		{
+			new_environ[i] = strdup(environ[i]);
+			if (!new_environ[i])
+			{
+				write_stderr("out of memory\n");
+				exit(1);
+			}
+		}
+		new_environ[i] = NULL;
+		environ = new_environ;
+	}
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+#if defined(PS_USE_CHANGE_ARGV) || defined(PS_USE_CLOBBER_ARGV)
+
+	/*
+	 * If we're going to change the original argv[] then make a copy for
+	 * argument parsing purposes.
+	 *
+	 * (NB: do NOT think to remove the copying of argv[], even though
+	 * postmaster.c finishes looking at argv[] long before we ever consider
+	 * changing the ps display.  On some platforms, getopt() keeps pointers
+	 * into the argv array, and will get horribly confused when it is
+	 * re-called to analyze a subprocess' argument string if the argv storage
+	 * has been clobbered meanwhile.  Other platforms have other dependencies
+	 * on argv[].
+	 */
+	{
+		char	  **new_argv;
+		int			i;
+
+		new_argv = (char **) malloc((argc + 1) * sizeof(char *));
+		if (!new_argv)
+		{
+			write_stderr("out of memory\n");
+			exit(1);
+		}
+		for (i = 0; i < argc; i++)
+		{
+			new_argv[i] = strdup(argv[i]);
+			if (!new_argv[i])
+			{
+				write_stderr("out of memory\n");
+				exit(1);
+			}
+		}
+		new_argv[argc] = NULL;
+
+#if defined(__darwin__)
+
+		/*
+		 * macOS (and perhaps other NeXT-derived platforms?) has a static copy
+		 * of the argv pointer, which we may fix like so:
+		 */
+		*_NSGetArgv() = new_argv;
+#endif
+
+		argv = new_argv;
+	}
+#endif							/* PS_USE_CHANGE_ARGV or PS_USE_CLOBBER_ARGV */
+
+	return argv;
+}
+
+/*
+ * Call this once during subprocess startup to set the identification
+ * values.
+ *
+ * If fixed_part is NULL, a default will be obtained from MyBackendType.
+ *
+ * At this point, the original argv[] array may be overwritten.
+ */
+void
+init_ps_display(const char *fixed_part)
+{
+#ifndef PS_USE_NONE
+	bool		save_update_process_title;
+#endif
+
+	Assert(fixed_part || MyBackendType);
+	if (!fixed_part)
+		fixed_part = GetBackendTypeDesc(MyBackendType);
+
+#ifndef PS_USE_NONE
+	/* no ps display for stand-alone backend */
+	if (!IsUnderPostmaster)
+		return;
+
+	/* no ps display if you didn't call save_ps_display_args() */
+	if (!save_argv)
+		return;
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+		return;
+#endif
+
+	/*
+	 * Overwrite argv[] to point at appropriate space, if needed
+	 */
+
+#ifdef PS_USE_CHANGE_ARGV
+	save_argv[0] = ps_buffer;
+	save_argv[1] = NULL;
+#endif							/* PS_USE_CHANGE_ARGV */
+
+#ifdef PS_USE_CLOBBER_ARGV
+	{
+		int			i;
+
+		/* make extra argv slots point at end_of_area (a NUL) */
+		for (i = 1; i < save_argc; i++)
+			save_argv[i] = ps_buffer + ps_buffer_size;
+	}
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+	/*
+	 * Make fixed prefix of ps display.
+	 */
+
+#if defined(PS_USE_SETPROCTITLE) || defined(PS_USE_SETPROCTITLE_FAST)
+
+	/*
+	 * apparently setproctitle() already adds a `progname:' prefix to the ps
+	 * line
+	 */
+#define PROGRAM_NAME_PREFIX ""
+#else
+#define PROGRAM_NAME_PREFIX "postgres: "
+#endif
+
+	if (*cluster_name == '\0')
+	{
+		snprintf(ps_buffer, ps_buffer_size,
+				 PROGRAM_NAME_PREFIX "%s ",
+				 fixed_part);
+	}
+	else
+	{
+		snprintf(ps_buffer, ps_buffer_size,
+				 PROGRAM_NAME_PREFIX "%s: %s ",
+				 cluster_name, fixed_part);
+	}
+
+	ps_buffer_cur_len = ps_buffer_fixed_size = strlen(ps_buffer);
+
+	/*
+	 * On the first run, force the update.
+	 */
+	save_update_process_title = update_process_title;
+	update_process_title = true;
+	set_ps_display("");
+	update_process_title = save_update_process_title;
+#endif							/* not PS_USE_NONE */
+}
+
+
+
+/*
+ * Call this to update the ps status display to a fixed prefix plus an
+ * indication of what you're currently doing passed in the argument.
+ */
+void
+set_ps_display(const char *activity)
+{
+#ifndef PS_USE_NONE
+	/* update_process_title=off disables updates */
+	if (!update_process_title)
+		return;
+
+	/* no ps display for stand-alone backend */
+	if (!IsUnderPostmaster)
+		return;
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+		return;
+#endif
+
+	/* Update ps_buffer to contain both fixed part and activity */
+	strlcpy(ps_buffer + ps_buffer_fixed_size, activity,
+			ps_buffer_size - ps_buffer_fixed_size);
+	ps_buffer_cur_len = strlen(ps_buffer);
+
+	/* Transmit new setting to kernel, if necessary */
+
+#ifdef PS_USE_SETPROCTITLE
+	setproctitle("%s", ps_buffer);
+#elif defined(PS_USE_SETPROCTITLE_FAST)
+	setproctitle_fast("%s", ps_buffer);
+#endif
+
+#ifdef PS_USE_PSTAT
+	{
+		union pstun pst;
+
+		pst.pst_command = ps_buffer;
+		pstat(PSTAT_SETCMD, pst, ps_buffer_cur_len, 0, 0);
+	}
+#endif							/* PS_USE_PSTAT */
+
+#ifdef PS_USE_PS_STRINGS
+	PS_STRINGS->ps_nargvstr = 1;
+	PS_STRINGS->ps_argvstr = ps_buffer;
+#endif							/* PS_USE_PS_STRINGS */
+
+#ifdef PS_USE_CLOBBER_ARGV
+	/* pad unused memory; need only clobber remainder of old status string */
+	if (last_status_len > ps_buffer_cur_len)
+		MemSet(ps_buffer + ps_buffer_cur_len, PS_PADDING,
+			   last_status_len - ps_buffer_cur_len);
+	last_status_len = ps_buffer_cur_len;
+#endif							/* PS_USE_CLOBBER_ARGV */
+
+#ifdef PS_USE_WIN32
+	{
+		/*
+		 * Win32 does not support showing any changed arguments. To make it at
+		 * all possible to track which backend is doing what, we create a
+		 * named object that can be viewed with for example Process Explorer.
+		 */
+		static HANDLE ident_handle = INVALID_HANDLE_VALUE;
+		char		name[PS_BUFFER_SIZE + 32];
+
+		if (ident_handle != INVALID_HANDLE_VALUE)
+			CloseHandle(ident_handle);
+
+		sprintf(name, "pgident(%d): %s", MyProcPid, ps_buffer);
+
+		ident_handle = CreateEvent(NULL, TRUE, FALSE, name);
+	}
+#endif							/* PS_USE_WIN32 */
+#endif							/* not PS_USE_NONE */
+}
+
+
+/*
+ * Returns what's currently in the ps display, in case someone needs
+ * it.  Note that only the activity part is returned.  On some platforms
+ * the string will not be null-terminated, so return the effective
+ * length into *displen.
+ */
+const char *
+get_ps_display(int *displen)
+{
+#ifdef PS_USE_CLOBBER_ARGV
+	/* If ps_buffer is a pointer, it might still be null */
+	if (!ps_buffer)
+	{
+		*displen = 0;
+		return "";
+	}
+#endif
+
+#ifndef PS_USE_NONE
+	*displen = (int) (ps_buffer_cur_len - ps_buffer_fixed_size);
+
+	return ps_buffer + ps_buffer_fixed_size;
+#else
+	*displen = 0;
+	return "";
+#endif
+}
diff --git a/src/backend/utils/misc/queryenvironment.c b/src/backend/utils/misc/queryenvironment.c
new file mode 100644
index 0000000..86d61d0
--- /dev/null
+++ b/src/backend/utils/misc/queryenvironment.c
@@ -0,0 +1,144 @@
+/*-------------------------------------------------------------------------
+ *
+ * queryenvironment.c
+ *	  Query environment, to store context-specific values like ephemeral named
+ *	  relations.  Initial use is for named tuplestores for delta information
+ *	  from "normal" relations.
+ *
+ * The initial implementation uses a list because the number of such relations
+ * in any one context is expected to be very small.  If that becomes a
+ * performance problem, the implementation can be changed with no other impact
+ * on callers, since this is an opaque structure.  This is the reason to
+ * require a create function.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/queryenvironment.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/table.h"
+#include "utils/queryenvironment.h"
+#include "utils/rel.h"
+
+/*
+ * Private state of a query environment.
+ */
+struct QueryEnvironment
+{
+	List	   *namedRelList;
+};
+
+
+QueryEnvironment *
+create_queryEnv(void)
+{
+	return (QueryEnvironment *) palloc0(sizeof(QueryEnvironment));
+}
+
+EphemeralNamedRelationMetadata
+get_visible_ENR_metadata(QueryEnvironment *queryEnv, const char *refname)
+{
+	EphemeralNamedRelation enr;
+
+	Assert(refname != NULL);
+
+	if (queryEnv == NULL)
+		return NULL;
+
+	enr = get_ENR(queryEnv, refname);
+
+	if (enr)
+		return &(enr->md);
+
+	return NULL;
+}
+
+/*
+ * Register a named relation for use in the given environment.
+ *
+ * If this is intended exclusively for planning purposes, the tstate field can
+ * be left NULL;
+ */
+void
+register_ENR(QueryEnvironment *queryEnv, EphemeralNamedRelation enr)
+{
+	Assert(enr != NULL);
+	Assert(get_ENR(queryEnv, enr->md.name) == NULL);
+
+	queryEnv->namedRelList = lappend(queryEnv->namedRelList, enr);
+}
+
+/*
+ * Unregister an ephemeral relation by name.  This will probably be a rarely
+ * used function, but seems like it should be provided "just in case".
+ */
+void
+unregister_ENR(QueryEnvironment *queryEnv, const char *name)
+{
+	EphemeralNamedRelation match;
+
+	match = get_ENR(queryEnv, name);
+	if (match)
+		queryEnv->namedRelList = list_delete(queryEnv->namedRelList, match);
+}
+
+/*
+ * This returns an ENR if there is a name match in the given collection.  It
+ * must quietly return NULL if no match is found.
+ */
+EphemeralNamedRelation
+get_ENR(QueryEnvironment *queryEnv, const char *name)
+{
+	ListCell   *lc;
+
+	Assert(name != NULL);
+
+	if (queryEnv == NULL)
+		return NULL;
+
+	foreach(lc, queryEnv->namedRelList)
+	{
+		EphemeralNamedRelation enr = (EphemeralNamedRelation) lfirst(lc);
+
+		if (strcmp(enr->md.name, name) == 0)
+			return enr;
+	}
+
+	return NULL;
+}
+
+/*
+ * Gets the TupleDesc for a Ephemeral Named Relation, based on which field was
+ * filled.
+ *
+ * When the TupleDesc is based on a relation from the catalogs, we count on
+ * that relation being used at the same time, so that appropriate locks will
+ * already be held.  Locking here would be too late anyway.
+ */
+TupleDesc
+ENRMetadataGetTupDesc(EphemeralNamedRelationMetadata enrmd)
+{
+	TupleDesc	tupdesc;
+
+	/* One, and only one, of these fields must be filled. */
+	Assert((enrmd->reliddesc == InvalidOid) != (enrmd->tupdesc == NULL));
+
+	if (enrmd->tupdesc != NULL)
+		tupdesc = enrmd->tupdesc;
+	else
+	{
+		Relation	relation;
+
+		relation = table_open(enrmd->reliddesc, NoLock);
+		tupdesc = relation->rd_att;
+		table_close(relation, NoLock);
+	}
+
+	return tupdesc;
+}
diff --git a/src/backend/utils/misc/queryjumble.c b/src/backend/utils/misc/queryjumble.c
new file mode 100644
index 0000000..9f2cd1f
--- /dev/null
+++ b/src/backend/utils/misc/queryjumble.c
@@ -0,0 +1,858 @@
+/*-------------------------------------------------------------------------
+ *
+ * queryjumble.c
+ *	 Query normalization and fingerprinting.
+ *
+ * Normalization is a process whereby similar queries, typically differing only
+ * in their constants (though the exact rules are somewhat more subtle than
+ * that) are recognized as equivalent, and are tracked as a single entry.  This
+ * is particularly useful for non-prepared queries.
+ *
+ * Normalization is implemented by fingerprinting queries, selectively
+ * serializing those fields of each query tree's nodes that are judged to be
+ * essential to the query.  This is referred to as a query jumble.  This is
+ * distinct from a regular serialization in that various extraneous
+ * information is ignored as irrelevant or not essential to the query, such
+ * as the collations of Vars and, most notably, the values of constants.
+ *
+ * This jumble is acquired at the end of parse analysis of each query, and
+ * a 64-bit hash of it is stored into the query's Query.queryId field.
+ * The server then copies this value around, making it available in plan
+ * tree(s) generated from the query.  The executor can then use this value
+ * to blame query costs on the proper queryId.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/queryjumble.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "common/hashfn.h"
+#include "miscadmin.h"
+#include "parser/scansup.h"
+#include "utils/queryjumble.h"
+
+#define JUMBLE_SIZE				1024	/* query serialization buffer size */
+
+/* GUC parameters */
+int			compute_query_id = COMPUTE_QUERY_ID_AUTO;
+
+/* True when compute_query_id is ON, or AUTO and a module requests them */
+bool		query_id_enabled = false;
+
+static uint64 compute_utility_query_id(const char *str, int query_location, int query_len);
+static void AppendJumble(JumbleState *jstate,
+						 const unsigned char *item, Size size);
+static void JumbleQueryInternal(JumbleState *jstate, Query *query);
+static void JumbleRangeTable(JumbleState *jstate, List *rtable);
+static void JumbleRowMarks(JumbleState *jstate, List *rowMarks);
+static void JumbleExpr(JumbleState *jstate, Node *node);
+static void RecordConstLocation(JumbleState *jstate, int location);
+
+/*
+ * Given a possibly multi-statement source string, confine our attention to the
+ * relevant part of the string.
+ */
+const char *
+CleanQuerytext(const char *query, int *location, int *len)
+{
+	int			query_location = *location;
+	int			query_len = *len;
+
+	/* First apply starting offset, unless it's -1 (unknown). */
+	if (query_location >= 0)
+	{
+		Assert(query_location <= strlen(query));
+		query += query_location;
+		/* Length of 0 (or -1) means "rest of string" */
+		if (query_len <= 0)
+			query_len = strlen(query);
+		else
+			Assert(query_len <= strlen(query));
+	}
+	else
+	{
+		/* If query location is unknown, distrust query_len as well */
+		query_location = 0;
+		query_len = strlen(query);
+	}
+
+	/*
+	 * Discard leading and trailing whitespace, too.  Use scanner_isspace()
+	 * not libc's isspace(), because we want to match the lexer's behavior.
+	 */
+	while (query_len > 0 && scanner_isspace(query[0]))
+		query++, query_location++, query_len--;
+	while (query_len > 0 && scanner_isspace(query[query_len - 1]))
+		query_len--;
+
+	*location = query_location;
+	*len = query_len;
+
+	return query;
+}
+
+JumbleState *
+JumbleQuery(Query *query, const char *querytext)
+{
+	JumbleState *jstate = NULL;
+
+	Assert(IsQueryIdEnabled());
+
+	if (query->utilityStmt)
+	{
+		query->queryId = compute_utility_query_id(querytext,
+												  query->stmt_location,
+												  query->stmt_len);
+	}
+	else
+	{
+		jstate = (JumbleState *) palloc(sizeof(JumbleState));
+
+		/* Set up workspace for query jumbling */
+		jstate->jumble = (unsigned char *) palloc(JUMBLE_SIZE);
+		jstate->jumble_len = 0;
+		jstate->clocations_buf_size = 32;
+		jstate->clocations = (LocationLen *)
+			palloc(jstate->clocations_buf_size * sizeof(LocationLen));
+		jstate->clocations_count = 0;
+		jstate->highest_extern_param_id = 0;
+
+		/* Compute query ID and mark the Query node with it */
+		JumbleQueryInternal(jstate, query);
+		query->queryId = DatumGetUInt64(hash_any_extended(jstate->jumble,
+														  jstate->jumble_len,
+														  0));
+
+		/*
+		 * If we are unlucky enough to get a hash of zero, use 1 instead, to
+		 * prevent confusion with the utility-statement case.
+		 */
+		if (query->queryId == UINT64CONST(0))
+			query->queryId = UINT64CONST(1);
+	}
+
+	return jstate;
+}
+
+/*
+ * Enables query identifier computation.
+ *
+ * Third-party plugins can use this function to inform core that they require
+ * a query identifier to be computed.
+ */
+void
+EnableQueryId(void)
+{
+	if (compute_query_id != COMPUTE_QUERY_ID_OFF)
+		query_id_enabled = true;
+}
+
+/*
+ * Compute a query identifier for the given utility query string.
+ */
+static uint64
+compute_utility_query_id(const char *query_text, int query_location, int query_len)
+{
+	uint64		queryId;
+	const char *sql;
+
+	/*
+	 * Confine our attention to the relevant part of the string, if the query
+	 * is a portion of a multi-statement source string.
+	 */
+	sql = CleanQuerytext(query_text, &query_location, &query_len);
+
+	queryId = DatumGetUInt64(hash_any_extended((const unsigned char *) sql,
+											   query_len, 0));
+
+	/*
+	 * If we are unlucky enough to get a hash of zero(invalid), use queryID as
+	 * 2 instead, queryID 1 is already in use for normal statements.
+	 */
+	if (queryId == UINT64CONST(0))
+		queryId = UINT64CONST(2);
+
+	return queryId;
+}
+
+/*
+ * AppendJumble: Append a value that is substantive in a given query to
+ * the current jumble.
+ */
+static void
+AppendJumble(JumbleState *jstate, const unsigned char *item, Size size)
+{
+	unsigned char *jumble = jstate->jumble;
+	Size		jumble_len = jstate->jumble_len;
+
+	/*
+	 * Whenever the jumble buffer is full, we hash the current contents and
+	 * reset the buffer to contain just that hash value, thus relying on the
+	 * hash to summarize everything so far.
+	 */
+	while (size > 0)
+	{
+		Size		part_size;
+
+		if (jumble_len >= JUMBLE_SIZE)
+		{
+			uint64		start_hash;
+
+			start_hash = DatumGetUInt64(hash_any_extended(jumble,
+														  JUMBLE_SIZE, 0));
+			memcpy(jumble, &start_hash, sizeof(start_hash));
+			jumble_len = sizeof(start_hash);
+		}
+		part_size = Min(size, JUMBLE_SIZE - jumble_len);
+		memcpy(jumble + jumble_len, item, part_size);
+		jumble_len += part_size;
+		item += part_size;
+		size -= part_size;
+	}
+	jstate->jumble_len = jumble_len;
+}
+
+/*
+ * Wrappers around AppendJumble to encapsulate details of serialization
+ * of individual local variable elements.
+ */
+#define APP_JUMB(item) \
+	AppendJumble(jstate, (const unsigned char *) &(item), sizeof(item))
+#define APP_JUMB_STRING(str) \
+	AppendJumble(jstate, (const unsigned char *) (str), strlen(str) + 1)
+
+/*
+ * JumbleQueryInternal: Selectively serialize the query tree, appending
+ * significant data to the "query jumble" while ignoring nonsignificant data.
+ *
+ * Rule of thumb for what to include is that we should ignore anything not
+ * semantically significant (such as alias names) as well as anything that can
+ * be deduced from child nodes (else we'd just be double-hashing that piece
+ * of information).
+ */
+static void
+JumbleQueryInternal(JumbleState *jstate, Query *query)
+{
+	Assert(IsA(query, Query));
+	Assert(query->utilityStmt == NULL);
+
+	APP_JUMB(query->commandType);
+	/* resultRelation is usually predictable from commandType */
+	JumbleExpr(jstate, (Node *) query->cteList);
+	JumbleRangeTable(jstate, query->rtable);
+	JumbleExpr(jstate, (Node *) query->jointree);
+	JumbleExpr(jstate, (Node *) query->targetList);
+	JumbleExpr(jstate, (Node *) query->onConflict);
+	JumbleExpr(jstate, (Node *) query->returningList);
+	JumbleExpr(jstate, (Node *) query->groupClause);
+	APP_JUMB(query->groupDistinct);
+	JumbleExpr(jstate, (Node *) query->groupingSets);
+	JumbleExpr(jstate, query->havingQual);
+	JumbleExpr(jstate, (Node *) query->windowClause);
+	JumbleExpr(jstate, (Node *) query->distinctClause);
+	JumbleExpr(jstate, (Node *) query->sortClause);
+	JumbleExpr(jstate, query->limitOffset);
+	JumbleExpr(jstate, query->limitCount);
+	APP_JUMB(query->limitOption);
+	JumbleRowMarks(jstate, query->rowMarks);
+	JumbleExpr(jstate, query->setOperations);
+}
+
+/*
+ * Jumble a range table
+ */
+static void
+JumbleRangeTable(JumbleState *jstate, List *rtable)
+{
+	ListCell   *lc;
+
+	foreach(lc, rtable)
+	{
+		RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);
+
+		APP_JUMB(rte->rtekind);
+		switch (rte->rtekind)
+		{
+			case RTE_RELATION:
+				APP_JUMB(rte->relid);
+				JumbleExpr(jstate, (Node *) rte->tablesample);
+				APP_JUMB(rte->inh);
+				break;
+			case RTE_SUBQUERY:
+				JumbleQueryInternal(jstate, rte->subquery);
+				break;
+			case RTE_JOIN:
+				APP_JUMB(rte->jointype);
+				break;
+			case RTE_FUNCTION:
+				JumbleExpr(jstate, (Node *) rte->functions);
+				break;
+			case RTE_TABLEFUNC:
+				JumbleExpr(jstate, (Node *) rte->tablefunc);
+				break;
+			case RTE_VALUES:
+				JumbleExpr(jstate, (Node *) rte->values_lists);
+				break;
+			case RTE_CTE:
+
+				/*
+				 * Depending on the CTE name here isn't ideal, but it's the
+				 * only info we have to identify the referenced WITH item.
+				 */
+				APP_JUMB_STRING(rte->ctename);
+				APP_JUMB(rte->ctelevelsup);
+				break;
+			case RTE_NAMEDTUPLESTORE:
+				APP_JUMB_STRING(rte->enrname);
+				break;
+			case RTE_RESULT:
+				break;
+			default:
+				elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
+				break;
+		}
+	}
+}
+
+/*
+ * Jumble a rowMarks list
+ */
+static void
+JumbleRowMarks(JumbleState *jstate, List *rowMarks)
+{
+	ListCell   *lc;
+
+	foreach(lc, rowMarks)
+	{
+		RowMarkClause *rowmark = lfirst_node(RowMarkClause, lc);
+
+		if (!rowmark->pushedDown)
+		{
+			APP_JUMB(rowmark->rti);
+			APP_JUMB(rowmark->strength);
+			APP_JUMB(rowmark->waitPolicy);
+		}
+	}
+}
+
+/*
+ * Jumble an expression tree
+ *
+ * In general this function should handle all the same node types that
+ * expression_tree_walker() does, and therefore it's coded to be as parallel
+ * to that function as possible.  However, since we are only invoked on
+ * queries immediately post-parse-analysis, we need not handle node types
+ * that only appear in planning.
+ *
+ * Note: the reason we don't simply use expression_tree_walker() is that the
+ * point of that function is to support tree walkers that don't care about
+ * most tree node types, but here we care about all types.  We should complain
+ * about any unrecognized node type.
+ */
+static void
+JumbleExpr(JumbleState *jstate, Node *node)
+{
+	ListCell   *temp;
+
+	if (node == NULL)
+		return;
+
+	/* Guard against stack overflow due to overly complex expressions */
+	check_stack_depth();
+
+	/*
+	 * We always emit the node's NodeTag, then any additional fields that are
+	 * considered significant, and then we recurse to any child nodes.
+	 */
+	APP_JUMB(node->type);
+
+	switch (nodeTag(node))
+	{
+		case T_Var:
+			{
+				Var		   *var = (Var *) node;
+
+				APP_JUMB(var->varno);
+				APP_JUMB(var->varattno);
+				APP_JUMB(var->varlevelsup);
+			}
+			break;
+		case T_Const:
+			{
+				Const	   *c = (Const *) node;
+
+				/* We jumble only the constant's type, not its value */
+				APP_JUMB(c->consttype);
+				/* Also, record its parse location for query normalization */
+				RecordConstLocation(jstate, c->location);
+			}
+			break;
+		case T_Param:
+			{
+				Param	   *p = (Param *) node;
+
+				APP_JUMB(p->paramkind);
+				APP_JUMB(p->paramid);
+				APP_JUMB(p->paramtype);
+				/* Also, track the highest external Param id */
+				if (p->paramkind == PARAM_EXTERN &&
+					p->paramid > jstate->highest_extern_param_id)
+					jstate->highest_extern_param_id = p->paramid;
+			}
+			break;
+		case T_Aggref:
+			{
+				Aggref	   *expr = (Aggref *) node;
+
+				APP_JUMB(expr->aggfnoid);
+				JumbleExpr(jstate, (Node *) expr->aggdirectargs);
+				JumbleExpr(jstate, (Node *) expr->args);
+				JumbleExpr(jstate, (Node *) expr->aggorder);
+				JumbleExpr(jstate, (Node *) expr->aggdistinct);
+				JumbleExpr(jstate, (Node *) expr->aggfilter);
+			}
+			break;
+		case T_GroupingFunc:
+			{
+				GroupingFunc *grpnode = (GroupingFunc *) node;
+
+				JumbleExpr(jstate, (Node *) grpnode->refs);
+				APP_JUMB(grpnode->agglevelsup);
+			}
+			break;
+		case T_WindowFunc:
+			{
+				WindowFunc *expr = (WindowFunc *) node;
+
+				APP_JUMB(expr->winfnoid);
+				APP_JUMB(expr->winref);
+				JumbleExpr(jstate, (Node *) expr->args);
+				JumbleExpr(jstate, (Node *) expr->aggfilter);
+			}
+			break;
+		case T_SubscriptingRef:
+			{
+				SubscriptingRef *sbsref = (SubscriptingRef *) node;
+
+				JumbleExpr(jstate, (Node *) sbsref->refupperindexpr);
+				JumbleExpr(jstate, (Node *) sbsref->reflowerindexpr);
+				JumbleExpr(jstate, (Node *) sbsref->refexpr);
+				JumbleExpr(jstate, (Node *) sbsref->refassgnexpr);
+			}
+			break;
+		case T_FuncExpr:
+			{
+				FuncExpr   *expr = (FuncExpr *) node;
+
+				APP_JUMB(expr->funcid);
+				JumbleExpr(jstate, (Node *) expr->args);
+			}
+			break;
+		case T_NamedArgExpr:
+			{
+				NamedArgExpr *nae = (NamedArgExpr *) node;
+
+				APP_JUMB(nae->argnumber);
+				JumbleExpr(jstate, (Node *) nae->arg);
+			}
+			break;
+		case T_OpExpr:
+		case T_DistinctExpr:	/* struct-equivalent to OpExpr */
+		case T_NullIfExpr:		/* struct-equivalent to OpExpr */
+			{
+				OpExpr	   *expr = (OpExpr *) node;
+
+				APP_JUMB(expr->opno);
+				JumbleExpr(jstate, (Node *) expr->args);
+			}
+			break;
+		case T_ScalarArrayOpExpr:
+			{
+				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
+
+				APP_JUMB(expr->opno);
+				APP_JUMB(expr->useOr);
+				JumbleExpr(jstate, (Node *) expr->args);
+			}
+			break;
+		case T_BoolExpr:
+			{
+				BoolExpr   *expr = (BoolExpr *) node;
+
+				APP_JUMB(expr->boolop);
+				JumbleExpr(jstate, (Node *) expr->args);
+			}
+			break;
+		case T_SubLink:
+			{
+				SubLink    *sublink = (SubLink *) node;
+
+				APP_JUMB(sublink->subLinkType);
+				APP_JUMB(sublink->subLinkId);
+				JumbleExpr(jstate, (Node *) sublink->testexpr);
+				JumbleQueryInternal(jstate, castNode(Query, sublink->subselect));
+			}
+			break;
+		case T_FieldSelect:
+			{
+				FieldSelect *fs = (FieldSelect *) node;
+
+				APP_JUMB(fs->fieldnum);
+				JumbleExpr(jstate, (Node *) fs->arg);
+			}
+			break;
+		case T_FieldStore:
+			{
+				FieldStore *fstore = (FieldStore *) node;
+
+				JumbleExpr(jstate, (Node *) fstore->arg);
+				JumbleExpr(jstate, (Node *) fstore->newvals);
+			}
+			break;
+		case T_RelabelType:
+			{
+				RelabelType *rt = (RelabelType *) node;
+
+				APP_JUMB(rt->resulttype);
+				JumbleExpr(jstate, (Node *) rt->arg);
+			}
+			break;
+		case T_CoerceViaIO:
+			{
+				CoerceViaIO *cio = (CoerceViaIO *) node;
+
+				APP_JUMB(cio->resulttype);
+				JumbleExpr(jstate, (Node *) cio->arg);
+			}
+			break;
+		case T_ArrayCoerceExpr:
+			{
+				ArrayCoerceExpr *acexpr = (ArrayCoerceExpr *) node;
+
+				APP_JUMB(acexpr->resulttype);
+				JumbleExpr(jstate, (Node *) acexpr->arg);
+				JumbleExpr(jstate, (Node *) acexpr->elemexpr);
+			}
+			break;
+		case T_ConvertRowtypeExpr:
+			{
+				ConvertRowtypeExpr *crexpr = (ConvertRowtypeExpr *) node;
+
+				APP_JUMB(crexpr->resulttype);
+				JumbleExpr(jstate, (Node *) crexpr->arg);
+			}
+			break;
+		case T_CollateExpr:
+			{
+				CollateExpr *ce = (CollateExpr *) node;
+
+				APP_JUMB(ce->collOid);
+				JumbleExpr(jstate, (Node *) ce->arg);
+			}
+			break;
+		case T_CaseExpr:
+			{
+				CaseExpr   *caseexpr = (CaseExpr *) node;
+
+				JumbleExpr(jstate, (Node *) caseexpr->arg);
+				foreach(temp, caseexpr->args)
+				{
+					CaseWhen   *when = lfirst_node(CaseWhen, temp);
+
+					JumbleExpr(jstate, (Node *) when->expr);
+					JumbleExpr(jstate, (Node *) when->result);
+				}
+				JumbleExpr(jstate, (Node *) caseexpr->defresult);
+			}
+			break;
+		case T_CaseTestExpr:
+			{
+				CaseTestExpr *ct = (CaseTestExpr *) node;
+
+				APP_JUMB(ct->typeId);
+			}
+			break;
+		case T_ArrayExpr:
+			JumbleExpr(jstate, (Node *) ((ArrayExpr *) node)->elements);
+			break;
+		case T_RowExpr:
+			JumbleExpr(jstate, (Node *) ((RowExpr *) node)->args);
+			break;
+		case T_RowCompareExpr:
+			{
+				RowCompareExpr *rcexpr = (RowCompareExpr *) node;
+
+				APP_JUMB(rcexpr->rctype);
+				JumbleExpr(jstate, (Node *) rcexpr->largs);
+				JumbleExpr(jstate, (Node *) rcexpr->rargs);
+			}
+			break;
+		case T_CoalesceExpr:
+			JumbleExpr(jstate, (Node *) ((CoalesceExpr *) node)->args);
+			break;
+		case T_MinMaxExpr:
+			{
+				MinMaxExpr *mmexpr = (MinMaxExpr *) node;
+
+				APP_JUMB(mmexpr->op);
+				JumbleExpr(jstate, (Node *) mmexpr->args);
+			}
+			break;
+		case T_SQLValueFunction:
+			{
+				SQLValueFunction *svf = (SQLValueFunction *) node;
+
+				APP_JUMB(svf->op);
+				/* type is fully determined by op */
+				APP_JUMB(svf->typmod);
+			}
+			break;
+		case T_XmlExpr:
+			{
+				XmlExpr    *xexpr = (XmlExpr *) node;
+
+				APP_JUMB(xexpr->op);
+				JumbleExpr(jstate, (Node *) xexpr->named_args);
+				JumbleExpr(jstate, (Node *) xexpr->args);
+			}
+			break;
+		case T_NullTest:
+			{
+				NullTest   *nt = (NullTest *) node;
+
+				APP_JUMB(nt->nulltesttype);
+				JumbleExpr(jstate, (Node *) nt->arg);
+			}
+			break;
+		case T_BooleanTest:
+			{
+				BooleanTest *bt = (BooleanTest *) node;
+
+				APP_JUMB(bt->booltesttype);
+				JumbleExpr(jstate, (Node *) bt->arg);
+			}
+			break;
+		case T_CoerceToDomain:
+			{
+				CoerceToDomain *cd = (CoerceToDomain *) node;
+
+				APP_JUMB(cd->resulttype);
+				JumbleExpr(jstate, (Node *) cd->arg);
+			}
+			break;
+		case T_CoerceToDomainValue:
+			{
+				CoerceToDomainValue *cdv = (CoerceToDomainValue *) node;
+
+				APP_JUMB(cdv->typeId);
+			}
+			break;
+		case T_SetToDefault:
+			{
+				SetToDefault *sd = (SetToDefault *) node;
+
+				APP_JUMB(sd->typeId);
+			}
+			break;
+		case T_CurrentOfExpr:
+			{
+				CurrentOfExpr *ce = (CurrentOfExpr *) node;
+
+				APP_JUMB(ce->cvarno);
+				if (ce->cursor_name)
+					APP_JUMB_STRING(ce->cursor_name);
+				APP_JUMB(ce->cursor_param);
+			}
+			break;
+		case T_NextValueExpr:
+			{
+				NextValueExpr *nve = (NextValueExpr *) node;
+
+				APP_JUMB(nve->seqid);
+				APP_JUMB(nve->typeId);
+			}
+			break;
+		case T_InferenceElem:
+			{
+				InferenceElem *ie = (InferenceElem *) node;
+
+				APP_JUMB(ie->infercollid);
+				APP_JUMB(ie->inferopclass);
+				JumbleExpr(jstate, ie->expr);
+			}
+			break;
+		case T_TargetEntry:
+			{
+				TargetEntry *tle = (TargetEntry *) node;
+
+				APP_JUMB(tle->resno);
+				APP_JUMB(tle->ressortgroupref);
+				JumbleExpr(jstate, (Node *) tle->expr);
+			}
+			break;
+		case T_RangeTblRef:
+			{
+				RangeTblRef *rtr = (RangeTblRef *) node;
+
+				APP_JUMB(rtr->rtindex);
+			}
+			break;
+		case T_JoinExpr:
+			{
+				JoinExpr   *join = (JoinExpr *) node;
+
+				APP_JUMB(join->jointype);
+				APP_JUMB(join->isNatural);
+				APP_JUMB(join->rtindex);
+				JumbleExpr(jstate, join->larg);
+				JumbleExpr(jstate, join->rarg);
+				JumbleExpr(jstate, join->quals);
+			}
+			break;
+		case T_FromExpr:
+			{
+				FromExpr   *from = (FromExpr *) node;
+
+				JumbleExpr(jstate, (Node *) from->fromlist);
+				JumbleExpr(jstate, from->quals);
+			}
+			break;
+		case T_OnConflictExpr:
+			{
+				OnConflictExpr *conf = (OnConflictExpr *) node;
+
+				APP_JUMB(conf->action);
+				JumbleExpr(jstate, (Node *) conf->arbiterElems);
+				JumbleExpr(jstate, conf->arbiterWhere);
+				JumbleExpr(jstate, (Node *) conf->onConflictSet);
+				JumbleExpr(jstate, conf->onConflictWhere);
+				APP_JUMB(conf->constraint);
+				APP_JUMB(conf->exclRelIndex);
+				JumbleExpr(jstate, (Node *) conf->exclRelTlist);
+			}
+			break;
+		case T_List:
+			foreach(temp, (List *) node)
+			{
+				JumbleExpr(jstate, (Node *) lfirst(temp));
+			}
+			break;
+		case T_IntList:
+			foreach(temp, (List *) node)
+			{
+				APP_JUMB(lfirst_int(temp));
+			}
+			break;
+		case T_SortGroupClause:
+			{
+				SortGroupClause *sgc = (SortGroupClause *) node;
+
+				APP_JUMB(sgc->tleSortGroupRef);
+				APP_JUMB(sgc->eqop);
+				APP_JUMB(sgc->sortop);
+				APP_JUMB(sgc->nulls_first);
+			}
+			break;
+		case T_GroupingSet:
+			{
+				GroupingSet *gsnode = (GroupingSet *) node;
+
+				JumbleExpr(jstate, (Node *) gsnode->content);
+			}
+			break;
+		case T_WindowClause:
+			{
+				WindowClause *wc = (WindowClause *) node;
+
+				APP_JUMB(wc->winref);
+				APP_JUMB(wc->frameOptions);
+				JumbleExpr(jstate, (Node *) wc->partitionClause);
+				JumbleExpr(jstate, (Node *) wc->orderClause);
+				JumbleExpr(jstate, wc->startOffset);
+				JumbleExpr(jstate, wc->endOffset);
+			}
+			break;
+		case T_CommonTableExpr:
+			{
+				CommonTableExpr *cte = (CommonTableExpr *) node;
+
+				/* we store the string name because RTE_CTE RTEs need it */
+				APP_JUMB_STRING(cte->ctename);
+				APP_JUMB(cte->ctematerialized);
+				JumbleQueryInternal(jstate, castNode(Query, cte->ctequery));
+			}
+			break;
+		case T_SetOperationStmt:
+			{
+				SetOperationStmt *setop = (SetOperationStmt *) node;
+
+				APP_JUMB(setop->op);
+				APP_JUMB(setop->all);
+				JumbleExpr(jstate, setop->larg);
+				JumbleExpr(jstate, setop->rarg);
+			}
+			break;
+		case T_RangeTblFunction:
+			{
+				RangeTblFunction *rtfunc = (RangeTblFunction *) node;
+
+				JumbleExpr(jstate, rtfunc->funcexpr);
+			}
+			break;
+		case T_TableFunc:
+			{
+				TableFunc  *tablefunc = (TableFunc *) node;
+
+				JumbleExpr(jstate, tablefunc->docexpr);
+				JumbleExpr(jstate, tablefunc->rowexpr);
+				JumbleExpr(jstate, (Node *) tablefunc->colexprs);
+			}
+			break;
+		case T_TableSampleClause:
+			{
+				TableSampleClause *tsc = (TableSampleClause *) node;
+
+				APP_JUMB(tsc->tsmhandler);
+				JumbleExpr(jstate, (Node *) tsc->args);
+				JumbleExpr(jstate, (Node *) tsc->repeatable);
+			}
+			break;
+		default:
+			/* Only a warning, since we can stumble along anyway */
+			elog(WARNING, "unrecognized node type: %d",
+				 (int) nodeTag(node));
+			break;
+	}
+}
+
+/*
+ * Record location of constant within query string of query tree
+ * that is currently being walked.
+ */
+static void
+RecordConstLocation(JumbleState *jstate, int location)
+{
+	/* -1 indicates unknown or undefined location */
+	if (location >= 0)
+	{
+		/* enlarge array if needed */
+		if (jstate->clocations_count >= jstate->clocations_buf_size)
+		{
+			jstate->clocations_buf_size *= 2;
+			jstate->clocations = (LocationLen *)
+				repalloc(jstate->clocations,
+						 jstate->clocations_buf_size *
+						 sizeof(LocationLen));
+		}
+		jstate->clocations[jstate->clocations_count].location = location;
+		/* initialize lengths to -1 to simplify third-party module usage */
+		jstate->clocations[jstate->clocations_count].length = -1;
+		jstate->clocations_count++;
+	}
+}
diff --git a/src/backend/utils/misc/rls.c b/src/backend/utils/misc/rls.c
new file mode 100644
index 0000000..13d2515
--- /dev/null
+++ b/src/backend/utils/misc/rls.c
@@ -0,0 +1,167 @@
+/*-------------------------------------------------------------------------
+ *
+ * rls.c
+ *		  RLS-related utility functions.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *		  src/backend/utils/misc/rls.c
+ *
+ *-------------------------------------------------------------------------
+*/
+#include "postgres.h"
+
+#include "access/htup.h"
+#include "access/htup_details.h"
+#include "access/transam.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_class.h"
+#include "miscadmin.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rls.h"
+#include "utils/syscache.h"
+#include "utils/varlena.h"
+
+
+/*
+ * check_enable_rls
+ *
+ * Determine, based on the relation, row_security setting, and current role,
+ * if RLS is applicable to this query.  RLS_NONE_ENV indicates that, while
+ * RLS is not to be added for this query, a change in the environment may change
+ * that.  RLS_NONE means that RLS is not on the relation at all and therefore
+ * we don't need to worry about it.  RLS_ENABLED means RLS should be implemented
+ * for the table and the plan cache needs to be invalidated if the environment
+ * changes.
+ *
+ * Handle checking as another role via checkAsUser (for views, etc).  Pass
+ * InvalidOid to check the current user.
+ *
+ * If noError is set to 'true' then we just return RLS_ENABLED instead of doing
+ * an ereport() if the user has attempted to bypass RLS and they are not
+ * allowed to.  This allows users to check if RLS is enabled without having to
+ * deal with the actual error case (eg: error cases which are trying to decide
+ * if the user should get data from the relation back as part of the error).
+ */
+int
+check_enable_rls(Oid relid, Oid checkAsUser, bool noError)
+{
+	Oid			user_id = checkAsUser ? checkAsUser : GetUserId();
+	HeapTuple	tuple;
+	Form_pg_class classform;
+	bool		relrowsecurity;
+	bool		relforcerowsecurity;
+	bool		amowner;
+
+	/* Nothing to do for built-in relations */
+	if (relid < (Oid) FirstNormalObjectId)
+		return RLS_NONE;
+
+	/* Fetch relation's relrowsecurity and relforcerowsecurity flags */
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		return RLS_NONE;
+	classform = (Form_pg_class) GETSTRUCT(tuple);
+
+	relrowsecurity = classform->relrowsecurity;
+	relforcerowsecurity = classform->relforcerowsecurity;
+
+	ReleaseSysCache(tuple);
+
+	/* Nothing to do if the relation does not have RLS */
+	if (!relrowsecurity)
+		return RLS_NONE;
+
+	/*
+	 * BYPASSRLS users always bypass RLS.  Note that superusers are always
+	 * considered to have BYPASSRLS.
+	 *
+	 * Return RLS_NONE_ENV to indicate that this decision depends on the
+	 * environment (in this case, the user_id).
+	 */
+	if (has_bypassrls_privilege(user_id))
+		return RLS_NONE_ENV;
+
+	/*
+	 * Table owners generally bypass RLS, except if the table has been set (by
+	 * an owner) to FORCE ROW SECURITY, and this is not a referential
+	 * integrity check.
+	 *
+	 * Return RLS_NONE_ENV to indicate that this decision depends on the
+	 * environment (in this case, the user_id).
+	 */
+	amowner = pg_class_ownercheck(relid, user_id);
+	if (amowner)
+	{
+		/*
+		 * If FORCE ROW LEVEL SECURITY has been set on the relation then we
+		 * should return RLS_ENABLED to indicate that RLS should be applied.
+		 * If not, or if we are in an InNoForceRLSOperation context, we return
+		 * RLS_NONE_ENV.
+		 *
+		 * InNoForceRLSOperation indicates that we should not apply RLS even
+		 * if the table has FORCE RLS set - IF the current user is the owner.
+		 * This is specifically to ensure that referential integrity checks
+		 * are able to still run correctly.
+		 *
+		 * This is intentionally only done after we have checked that the user
+		 * is the table owner, which should always be the case for referential
+		 * integrity checks.
+		 */
+		if (!relforcerowsecurity || InNoForceRLSOperation())
+			return RLS_NONE_ENV;
+	}
+
+	/*
+	 * We should apply RLS.  However, the user may turn off the row_security
+	 * GUC to get a forced error instead.
+	 */
+	if (!row_security && !noError)
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("query would be affected by row-level security policy for table \"%s\"",
+						get_rel_name(relid)),
+				 amowner ? errhint("To disable the policy for the table's owner, use ALTER TABLE NO FORCE ROW LEVEL SECURITY.") : 0));
+
+	/* RLS should be fully enabled for this relation. */
+	return RLS_ENABLED;
+}
+
+/*
+ * row_security_active
+ *
+ * check_enable_rls wrapped as a SQL callable function except
+ * RLS_NONE_ENV and RLS_NONE are the same for this purpose.
+ */
+Datum
+row_security_active(PG_FUNCTION_ARGS)
+{
+	/* By OID */
+	Oid			tableoid = PG_GETARG_OID(0);
+	int			rls_status;
+
+	rls_status = check_enable_rls(tableoid, InvalidOid, true);
+	PG_RETURN_BOOL(rls_status == RLS_ENABLED);
+}
+
+Datum
+row_security_active_name(PG_FUNCTION_ARGS)
+{
+	/* By qualified name */
+	text	   *tablename = PG_GETARG_TEXT_PP(0);
+	RangeVar   *tablerel;
+	Oid			tableoid;
+	int			rls_status;
+
+	/* Look up table name.  Can't lock it - we might not have privileges. */
+	tablerel = makeRangeVarFromNameList(textToQualifiedNameList(tablename));
+	tableoid = RangeVarGetRelid(tablerel, NoLock, false);
+
+	rls_status = check_enable_rls(tableoid, InvalidOid, true);
+	PG_RETURN_BOOL(rls_status == RLS_ENABLED);
+}
diff --git a/src/backend/utils/misc/sampling.c b/src/backend/utils/misc/sampling.c
new file mode 100644
index 0000000..0c327e8
--- /dev/null
+++ b/src/backend/utils/misc/sampling.c
@@ -0,0 +1,296 @@
+/*-------------------------------------------------------------------------
+ *
+ * sampling.c
+ *	  Relation block sampling routines.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/sampling.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <math.h>
+
+#include "utils/sampling.h"
+
+
+/*
+ * BlockSampler_Init -- prepare for random sampling of blocknumbers
+ *
+ * BlockSampler provides algorithm for block level sampling of a relation
+ * as discussed on pgsql-hackers 2004-04-02 (subject "Large DB")
+ * It selects a random sample of samplesize blocks out of
+ * the nblocks blocks in the table. If the table has less than
+ * samplesize blocks, all blocks are selected.
+ *
+ * Since we know the total number of blocks in advance, we can use the
+ * straightforward Algorithm S from Knuth 3.4.2, rather than Vitter's
+ * algorithm.
+ *
+ * Returns the number of blocks that BlockSampler_Next will return.
+ */
+BlockNumber
+BlockSampler_Init(BlockSampler bs, BlockNumber nblocks, int samplesize,
+				  long randseed)
+{
+	bs->N = nblocks;			/* measured table size */
+
+	/*
+	 * If we decide to reduce samplesize for tables that have less or not much
+	 * more than samplesize blocks, here is the place to do it.
+	 */
+	bs->n = samplesize;
+	bs->t = 0;					/* blocks scanned so far */
+	bs->m = 0;					/* blocks selected so far */
+
+	sampler_random_init_state(randseed, bs->randstate);
+
+	return Min(bs->n, bs->N);
+}
+
+bool
+BlockSampler_HasMore(BlockSampler bs)
+{
+	return (bs->t < bs->N) && (bs->m < bs->n);
+}
+
+BlockNumber
+BlockSampler_Next(BlockSampler bs)
+{
+	BlockNumber K = bs->N - bs->t;	/* remaining blocks */
+	int			k = bs->n - bs->m;	/* blocks still to sample */
+	double		p;				/* probability to skip block */
+	double		V;				/* random */
+
+	Assert(BlockSampler_HasMore(bs));	/* hence K > 0 and k > 0 */
+
+	if ((BlockNumber) k >= K)
+	{
+		/* need all the rest */
+		bs->m++;
+		return bs->t++;
+	}
+
+	/*----------
+	 * It is not obvious that this code matches Knuth's Algorithm S.
+	 * Knuth says to skip the current block with probability 1 - k/K.
+	 * If we are to skip, we should advance t (hence decrease K), and
+	 * repeat the same probabilistic test for the next block.  The naive
+	 * implementation thus requires a sampler_random_fract() call for each
+	 * block number.  But we can reduce this to one sampler_random_fract()
+	 * call per selected block, by noting that each time the while-test
+	 * succeeds, we can reinterpret V as a uniform random number in the range
+	 * 0 to p. Therefore, instead of choosing a new V, we just adjust p to be
+	 * the appropriate fraction of its former value, and our next loop
+	 * makes the appropriate probabilistic test.
+	 *
+	 * We have initially K > k > 0.  If the loop reduces K to equal k,
+	 * the next while-test must fail since p will become exactly zero
+	 * (we assume there will not be roundoff error in the division).
+	 * (Note: Knuth suggests a "<=" loop condition, but we use "<" just
+	 * to be doubly sure about roundoff error.)  Therefore K cannot become
+	 * less than k, which means that we cannot fail to select enough blocks.
+	 *----------
+	 */
+	V = sampler_random_fract(bs->randstate);
+	p = 1.0 - (double) k / (double) K;
+	while (V < p)
+	{
+		/* skip */
+		bs->t++;
+		K--;					/* keep K == N - t */
+
+		/* adjust p to be new cutoff point in reduced range */
+		p *= 1.0 - (double) k / (double) K;
+	}
+
+	/* select */
+	bs->m++;
+	return bs->t++;
+}
+
+/*
+ * These two routines embody Algorithm Z from "Random sampling with a
+ * reservoir" by Jeffrey S. Vitter, in ACM Trans. Math. Softw. 11, 1
+ * (Mar. 1985), Pages 37-57.  Vitter describes his algorithm in terms
+ * of the count S of records to skip before processing another record.
+ * It is computed primarily based on t, the number of records already read.
+ * The only extra state needed between calls is W, a random state variable.
+ *
+ * reservoir_init_selection_state computes the initial W value.
+ *
+ * Given that we've already read t records (t >= n), reservoir_get_next_S
+ * determines the number of records to skip before the next record is
+ * processed.
+ */
+void
+reservoir_init_selection_state(ReservoirState rs, int n)
+{
+	/*
+	 * Reservoir sampling is not used anywhere where it would need to return
+	 * repeatable results so we can initialize it randomly.
+	 */
+	sampler_random_init_state(random(), rs->randstate);
+
+	/* Initial value of W (for use when Algorithm Z is first applied) */
+	rs->W = exp(-log(sampler_random_fract(rs->randstate)) / n);
+}
+
+double
+reservoir_get_next_S(ReservoirState rs, double t, int n)
+{
+	double		S;
+
+	/* The magic constant here is T from Vitter's paper */
+	if (t <= (22.0 * n))
+	{
+		/* Process records using Algorithm X until t is large enough */
+		double		V,
+					quot;
+
+		V = sampler_random_fract(rs->randstate);	/* Generate V */
+		S = 0;
+		t += 1;
+		/* Note: "num" in Vitter's code is always equal to t - n */
+		quot = (t - (double) n) / t;
+		/* Find min S satisfying (4.1) */
+		while (quot > V)
+		{
+			S += 1;
+			t += 1;
+			quot *= (t - (double) n) / t;
+		}
+	}
+	else
+	{
+		/* Now apply Algorithm Z */
+		double		W = rs->W;
+		double		term = t - (double) n + 1;
+
+		for (;;)
+		{
+			double		numer,
+						numer_lim,
+						denom;
+			double		U,
+						X,
+						lhs,
+						rhs,
+						y,
+						tmp;
+
+			/* Generate U and X */
+			U = sampler_random_fract(rs->randstate);
+			X = t * (W - 1.0);
+			S = floor(X);		/* S is tentatively set to floor(X) */
+			/* Test if U <= h(S)/cg(X) in the manner of (6.3) */
+			tmp = (t + 1) / term;
+			lhs = exp(log(((U * tmp * tmp) * (term + S)) / (t + X)) / n);
+			rhs = (((t + X) / (term + S)) * term) / t;
+			if (lhs <= rhs)
+			{
+				W = rhs / lhs;
+				break;
+			}
+			/* Test if U <= f(S)/cg(X) */
+			y = (((U * (t + 1)) / term) * (t + S + 1)) / (t + X);
+			if ((double) n < S)
+			{
+				denom = t;
+				numer_lim = term + S;
+			}
+			else
+			{
+				denom = t - (double) n + S;
+				numer_lim = t + 1;
+			}
+			for (numer = t + S; numer >= numer_lim; numer -= 1)
+			{
+				y *= numer / denom;
+				denom -= 1;
+			}
+			W = exp(-log(sampler_random_fract(rs->randstate)) / n); /* Generate W in advance */
+			if (exp(log(y) / n) <= (t + X) / t)
+				break;
+		}
+		rs->W = W;
+	}
+	return S;
+}
+
+
+/*----------
+ * Random number generator used by sampling
+ *----------
+ */
+void
+sampler_random_init_state(long seed, SamplerRandomState randstate)
+{
+	randstate[0] = 0x330e;		/* same as pg_erand48, but could be anything */
+	randstate[1] = (unsigned short) seed;
+	randstate[2] = (unsigned short) (seed >> 16);
+}
+
+/* Select a random value R uniformly distributed in (0 - 1) */
+double
+sampler_random_fract(SamplerRandomState randstate)
+{
+	double		res;
+
+	/* pg_erand48 returns a value in [0.0 - 1.0), so we must reject 0 */
+	do
+	{
+		res = pg_erand48(randstate);
+	} while (res == 0.0);
+	return res;
+}
+
+
+/*
+ * Backwards-compatible API for block sampling
+ *
+ * This code is now deprecated, but since it's still in use by many FDWs,
+ * we should keep it for awhile at least.  The functionality is the same as
+ * sampler_random_fract/reservoir_init_selection_state/reservoir_get_next_S,
+ * except that a common random state is used across all callers.
+ */
+static ReservoirStateData oldrs;
+
+double
+anl_random_fract(void)
+{
+	/* initialize if first time through */
+	if (oldrs.randstate[0] == 0)
+		sampler_random_init_state(random(), oldrs.randstate);
+
+	/* and compute a random fraction */
+	return sampler_random_fract(oldrs.randstate);
+}
+
+double
+anl_init_selection_state(int n)
+{
+	/* initialize if first time through */
+	if (oldrs.randstate[0] == 0)
+		sampler_random_init_state(random(), oldrs.randstate);
+
+	/* Initial value of W (for use when Algorithm Z is first applied) */
+	return exp(-log(sampler_random_fract(oldrs.randstate)) / n);
+}
+
+double
+anl_get_next_S(double t, int n, double *stateptr)
+{
+	double		result;
+
+	oldrs.W = *stateptr;
+	result = reservoir_get_next_S(&oldrs, t, n);
+	*stateptr = oldrs.W;
+	return result;
+}
diff --git a/src/backend/utils/misc/superuser.c b/src/backend/utils/misc/superuser.c
new file mode 100644
index 0000000..9ec5a40
--- /dev/null
+++ b/src/backend/utils/misc/superuser.c
@@ -0,0 +1,107 @@
+/*-------------------------------------------------------------------------
+ *
+ * superuser.c
+ *	  The superuser() function.  Determines if user has superuser privilege.
+ *
+ * All code should use either of these two functions to find out
+ * whether a given user is a superuser, rather than examining
+ * pg_authid.rolsuper directly, so that the escape hatch built in for
+ * the single-user case works.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/superuser.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_authid.h"
+#include "miscadmin.h"
+#include "utils/inval.h"
+#include "utils/syscache.h"
+
+/*
+ * In common cases the same roleid (ie, the session or current ID) will
+ * be queried repeatedly.  So we maintain a simple one-entry cache for
+ * the status of the last requested roleid.  The cache can be flushed
+ * at need by watching for cache update events on pg_authid.
+ */
+static Oid	last_roleid = InvalidOid;	/* InvalidOid == cache not valid */
+static bool last_roleid_is_super = false;
+static bool roleid_callback_registered = false;
+
+static void RoleidCallback(Datum arg, int cacheid, uint32 hashvalue);
+
+
+/*
+ * The Postgres user running this command has Postgres superuser privileges
+ */
+bool
+superuser(void)
+{
+	return superuser_arg(GetUserId());
+}
+
+
+/*
+ * The specified role has Postgres superuser privileges
+ */
+bool
+superuser_arg(Oid roleid)
+{
+	bool		result;
+	HeapTuple	rtup;
+
+	/* Quick out for cache hit */
+	if (OidIsValid(last_roleid) && last_roleid == roleid)
+		return last_roleid_is_super;
+
+	/* Special escape path in case you deleted all your users. */
+	if (!IsUnderPostmaster && roleid == BOOTSTRAP_SUPERUSERID)
+		return true;
+
+	/* OK, look up the information in pg_authid */
+	rtup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
+	if (HeapTupleIsValid(rtup))
+	{
+		result = ((Form_pg_authid) GETSTRUCT(rtup))->rolsuper;
+		ReleaseSysCache(rtup);
+	}
+	else
+	{
+		/* Report "not superuser" for invalid roleids */
+		result = false;
+	}
+
+	/* If first time through, set up callback for cache flushes */
+	if (!roleid_callback_registered)
+	{
+		CacheRegisterSyscacheCallback(AUTHOID,
+									  RoleidCallback,
+									  (Datum) 0);
+		roleid_callback_registered = true;
+	}
+
+	/* Cache the result for next time */
+	last_roleid = roleid;
+	last_roleid_is_super = result;
+
+	return result;
+}
+
+/*
+ * RoleidCallback
+ *		Syscache inval callback function
+ */
+static void
+RoleidCallback(Datum arg, int cacheid, uint32 hashvalue)
+{
+	/* Invalidate our local cache in case role's superuserness changed */
+	last_roleid = InvalidOid;
+}
diff --git a/src/backend/utils/misc/timeout.c b/src/backend/utils/misc/timeout.c
new file mode 100644
index 0000000..b79df17
--- /dev/null
+++ b/src/backend/utils/misc/timeout.c
@@ -0,0 +1,779 @@
+/*-------------------------------------------------------------------------
+ *
+ * timeout.c
+ *	  Routines to multiplex SIGALRM interrupts for multiple timeout reasons.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/timeout.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <sys/time.h>
+
+#include "miscadmin.h"
+#include "storage/proc.h"
+#include "utils/timeout.h"
+#include "utils/timestamp.h"
+
+
+/* Data about any one timeout reason */
+typedef struct timeout_params
+{
+	TimeoutId	index;			/* identifier of timeout reason */
+
+	/* volatile because these may be changed from the signal handler */
+	volatile bool active;		/* true if timeout is in active_timeouts[] */
+	volatile bool indicator;	/* true if timeout has occurred */
+
+	/* callback function for timeout, or NULL if timeout not registered */
+	timeout_handler_proc timeout_handler;
+
+	TimestampTz start_time;		/* time that timeout was last activated */
+	TimestampTz fin_time;		/* time it is, or was last, due to fire */
+} timeout_params;
+
+/*
+ * List of possible timeout reasons in the order of enum TimeoutId.
+ */
+static timeout_params all_timeouts[MAX_TIMEOUTS];
+static bool all_timeouts_initialized = false;
+
+/*
+ * List of active timeouts ordered by their fin_time and priority.
+ * This list is subject to change by the interrupt handler, so it's volatile.
+ */
+static volatile int num_active_timeouts = 0;
+static timeout_params *volatile active_timeouts[MAX_TIMEOUTS];
+
+/*
+ * Flag controlling whether the signal handler is allowed to do anything.
+ * This is useful to avoid race conditions with the handler.  Note in
+ * particular that this lets us make changes in the data structures without
+ * tediously disabling and re-enabling the timer signal.  Most of the time,
+ * no interrupt would happen anyway during such critical sections, but if
+ * one does, this rule ensures it's safe.  Leaving the signal enabled across
+ * multiple operations can greatly reduce the number of kernel calls we make,
+ * too.  See comments in schedule_alarm() about that.
+ *
+ * We leave this "false" when we're not expecting interrupts, just in case.
+ */
+static volatile sig_atomic_t alarm_enabled = false;
+
+#define disable_alarm() (alarm_enabled = false)
+#define enable_alarm()	(alarm_enabled = true)
+
+/*
+ * State recording if and when we next expect the interrupt to fire.
+ * (signal_due_at is valid only when signal_pending is true.)
+ * Note that the signal handler will unconditionally reset signal_pending to
+ * false, so that can change asynchronously even when alarm_enabled is false.
+ */
+static volatile sig_atomic_t signal_pending = false;
+static volatile TimestampTz signal_due_at = 0;
+
+
+/*****************************************************************************
+ * Internal helper functions
+ *
+ * For all of these, it is caller's responsibility to protect them from
+ * interruption by the signal handler.  Generally, call disable_alarm()
+ * first to prevent interruption, then update state, and last call
+ * schedule_alarm(), which will re-enable the signal handler if needed.
+ *****************************************************************************/
+
+/*
+ * Find the index of a given timeout reason in the active array.
+ * If it's not there, return -1.
+ */
+static int
+find_active_timeout(TimeoutId id)
+{
+	int			i;
+
+	for (i = 0; i < num_active_timeouts; i++)
+	{
+		if (active_timeouts[i]->index == id)
+			return i;
+	}
+
+	return -1;
+}
+
+/*
+ * Insert specified timeout reason into the list of active timeouts
+ * at the given index.
+ */
+static void
+insert_timeout(TimeoutId id, int index)
+{
+	int			i;
+
+	if (index < 0 || index > num_active_timeouts)
+		elog(FATAL, "timeout index %d out of range 0..%d", index,
+			 num_active_timeouts);
+
+	Assert(!all_timeouts[id].active);
+	all_timeouts[id].active = true;
+
+	for (i = num_active_timeouts - 1; i >= index; i--)
+		active_timeouts[i + 1] = active_timeouts[i];
+
+	active_timeouts[index] = &all_timeouts[id];
+
+	num_active_timeouts++;
+}
+
+/*
+ * Remove the index'th element from the timeout list.
+ */
+static void
+remove_timeout_index(int index)
+{
+	int			i;
+
+	if (index < 0 || index >= num_active_timeouts)
+		elog(FATAL, "timeout index %d out of range 0..%d", index,
+			 num_active_timeouts - 1);
+
+	Assert(active_timeouts[index]->active);
+	active_timeouts[index]->active = false;
+
+	for (i = index + 1; i < num_active_timeouts; i++)
+		active_timeouts[i - 1] = active_timeouts[i];
+
+	num_active_timeouts--;
+}
+
+/*
+ * Enable the specified timeout reason
+ */
+static void
+enable_timeout(TimeoutId id, TimestampTz now, TimestampTz fin_time)
+{
+	int			i;
+
+	/* Assert request is sane */
+	Assert(all_timeouts_initialized);
+	Assert(all_timeouts[id].timeout_handler != NULL);
+
+	/*
+	 * If this timeout was already active, momentarily disable it.  We
+	 * interpret the call as a directive to reschedule the timeout.
+	 */
+	if (all_timeouts[id].active)
+		remove_timeout_index(find_active_timeout(id));
+
+	/*
+	 * Find out the index where to insert the new timeout.  We sort by
+	 * fin_time, and for equal fin_time by priority.
+	 */
+	for (i = 0; i < num_active_timeouts; i++)
+	{
+		timeout_params *old_timeout = active_timeouts[i];
+
+		if (fin_time < old_timeout->fin_time)
+			break;
+		if (fin_time == old_timeout->fin_time && id < old_timeout->index)
+			break;
+	}
+
+	/*
+	 * Mark the timeout active, and insert it into the active list.
+	 */
+	all_timeouts[id].indicator = false;
+	all_timeouts[id].start_time = now;
+	all_timeouts[id].fin_time = fin_time;
+
+	insert_timeout(id, i);
+}
+
+/*
+ * Schedule alarm for the next active timeout, if any
+ *
+ * We assume the caller has obtained the current time, or a close-enough
+ * approximation.  (It's okay if a tick or two has passed since "now", or
+ * if a little more time elapses before we reach the kernel call; that will
+ * cause us to ask for an interrupt a tick or two later than the nearest
+ * timeout, which is no big deal.  Passing a "now" value that's in the future
+ * would be bad though.)
+ */
+static void
+schedule_alarm(TimestampTz now)
+{
+	if (num_active_timeouts > 0)
+	{
+		struct itimerval timeval;
+		TimestampTz nearest_timeout;
+		long		secs;
+		int			usecs;
+
+		MemSet(&timeval, 0, sizeof(struct itimerval));
+
+		/*
+		 * If we think there's a signal pending, but current time is more than
+		 * 10ms past when the signal was due, then assume that the timeout
+		 * request got lost somehow; clear signal_pending so that we'll reset
+		 * the interrupt request below.  (10ms corresponds to the worst-case
+		 * timeout granularity on modern systems.)  It won't hurt us if the
+		 * interrupt does manage to fire between now and when we reach the
+		 * setitimer() call.
+		 */
+		if (signal_pending && now > signal_due_at + 10 * 1000)
+			signal_pending = false;
+
+		/*
+		 * Get the time remaining till the nearest pending timeout.  If it is
+		 * negative, assume that we somehow missed an interrupt, and clear
+		 * signal_pending.  This gives us another chance to recover if the
+		 * kernel drops a timeout request for some reason.
+		 */
+		nearest_timeout = active_timeouts[0]->fin_time;
+		if (now > nearest_timeout)
+		{
+			signal_pending = false;
+			/* force an interrupt as soon as possible */
+			secs = 0;
+			usecs = 1;
+		}
+		else
+		{
+			TimestampDifference(now, nearest_timeout,
+								&secs, &usecs);
+
+			/*
+			 * It's possible that the difference is less than a microsecond;
+			 * ensure we don't cancel, rather than set, the interrupt.
+			 */
+			if (secs == 0 && usecs == 0)
+				usecs = 1;
+		}
+
+		timeval.it_value.tv_sec = secs;
+		timeval.it_value.tv_usec = usecs;
+
+		/*
+		 * We must enable the signal handler before calling setitimer(); if we
+		 * did it in the other order, we'd have a race condition wherein the
+		 * interrupt could occur before we can set alarm_enabled, so that the
+		 * signal handler would fail to do anything.
+		 *
+		 * Because we didn't bother to disable the timer in disable_alarm(),
+		 * it's possible that a previously-set interrupt will fire between
+		 * enable_alarm() and setitimer().  This is safe, however.  There are
+		 * two possible outcomes:
+		 *
+		 * 1. The signal handler finds nothing to do (because the nearest
+		 * timeout event is still in the future).  It will re-set the timer
+		 * and return.  Then we'll overwrite the timer value with a new one.
+		 * This will mean that the timer fires a little later than we
+		 * intended, but only by the amount of time it takes for the signal
+		 * handler to do nothing useful, which shouldn't be much.
+		 *
+		 * 2. The signal handler executes and removes one or more timeout
+		 * events.  When it returns, either the queue is now empty or the
+		 * frontmost event is later than the one we looked at above.  So we'll
+		 * overwrite the timer value with one that is too soon (plus or minus
+		 * the signal handler's execution time), causing a useless interrupt
+		 * to occur.  But the handler will then re-set the timer and
+		 * everything will still work as expected.
+		 *
+		 * Since these cases are of very low probability (the window here
+		 * being quite narrow), it's not worth adding cycles to the mainline
+		 * code to prevent occasional wasted interrupts.
+		 */
+		enable_alarm();
+
+		/*
+		 * If there is already an interrupt pending that's at or before the
+		 * needed time, we need not do anything more.  The signal handler will
+		 * do the right thing in the first case, and re-schedule the interrupt
+		 * for later in the second case.  It might seem that the extra
+		 * interrupt is wasted work, but it's not terribly much work, and this
+		 * method has very significant advantages in the common use-case where
+		 * we repeatedly set a timeout that we don't expect to reach and then
+		 * cancel it.  Instead of invoking setitimer() every time the timeout
+		 * is set or canceled, we perform one interrupt and a re-scheduling
+		 * setitimer() call at intervals roughly equal to the timeout delay.
+		 * For example, with statement_timeout = 1s and a throughput of
+		 * thousands of queries per second, this method requires an interrupt
+		 * and setitimer() call roughly once a second, rather than thousands
+		 * of setitimer() calls per second.
+		 *
+		 * Because of the possible passage of time between when we obtained
+		 * "now" and when we reach setitimer(), the kernel's opinion of when
+		 * to trigger the interrupt is likely to be a bit later than
+		 * signal_due_at.  That's fine, for the same reasons described above.
+		 */
+		if (signal_pending && nearest_timeout >= signal_due_at)
+			return;
+
+		/*
+		 * As with calling enable_alarm(), we must set signal_pending *before*
+		 * calling setitimer(); if we did it after, the signal handler could
+		 * trigger before we set it, leaving us with a false opinion that a
+		 * signal is still coming.
+		 *
+		 * Other race conditions involved with setting/checking signal_pending
+		 * are okay, for the reasons described above.  One additional point is
+		 * that the signal handler could fire after we set signal_due_at, but
+		 * still before the setitimer() call.  Then the handler could
+		 * overwrite signal_due_at with a value it computes, which will be the
+		 * same as or perhaps later than what we just computed.  After we
+		 * perform setitimer(), the net effect would be that signal_due_at
+		 * gives a time later than when the interrupt will really happen;
+		 * which is a safe situation.
+		 */
+		signal_due_at = nearest_timeout;
+		signal_pending = true;
+
+		/* Set the alarm timer */
+		if (setitimer(ITIMER_REAL, &timeval, NULL) != 0)
+		{
+			/*
+			 * Clearing signal_pending here is a bit pro forma, but not
+			 * entirely so, since something in the FATAL exit path could try
+			 * to use timeout facilities.
+			 */
+			signal_pending = false;
+			elog(FATAL, "could not enable SIGALRM timer: %m");
+		}
+	}
+}
+
+
+/*****************************************************************************
+ * Signal handler
+ *****************************************************************************/
+
+/*
+ * Signal handler for SIGALRM
+ *
+ * Process any active timeout reasons and then reschedule the interrupt
+ * as needed.
+ */
+static void
+handle_sig_alarm(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	/*
+	 * Bump the holdoff counter, to make sure nothing we call will process
+	 * interrupts directly. No timeout handler should do that, but these
+	 * failures are hard to debug, so better be sure.
+	 */
+	HOLD_INTERRUPTS();
+
+	/*
+	 * SIGALRM is always cause for waking anything waiting on the process
+	 * latch.
+	 */
+	SetLatch(MyLatch);
+
+	/*
+	 * Always reset signal_pending, even if !alarm_enabled, since indeed no
+	 * signal is now pending.
+	 */
+	signal_pending = false;
+
+	/*
+	 * Fire any pending timeouts, but only if we're enabled to do so.
+	 */
+	if (alarm_enabled)
+	{
+		/*
+		 * Disable alarms, just in case this platform allows signal handlers
+		 * to interrupt themselves.  schedule_alarm() will re-enable if
+		 * appropriate.
+		 */
+		disable_alarm();
+
+		if (num_active_timeouts > 0)
+		{
+			TimestampTz now = GetCurrentTimestamp();
+
+			/* While the first pending timeout has been reached ... */
+			while (num_active_timeouts > 0 &&
+				   now >= active_timeouts[0]->fin_time)
+			{
+				timeout_params *this_timeout = active_timeouts[0];
+
+				/* Remove it from the active list */
+				remove_timeout_index(0);
+
+				/* Mark it as fired */
+				this_timeout->indicator = true;
+
+				/* And call its handler function */
+				this_timeout->timeout_handler();
+
+				/*
+				 * The handler might not take negligible time (CheckDeadLock
+				 * for instance isn't too cheap), so let's update our idea of
+				 * "now" after each one.
+				 */
+				now = GetCurrentTimestamp();
+			}
+
+			/* Done firing timeouts, so reschedule next interrupt if any */
+			schedule_alarm(now);
+		}
+	}
+
+	RESUME_INTERRUPTS();
+
+	errno = save_errno;
+}
+
+
+/*****************************************************************************
+ * Public API
+ *****************************************************************************/
+
+/*
+ * Initialize timeout module.
+ *
+ * This must be called in every process that wants to use timeouts.
+ *
+ * If the process was forked from another one that was also using this
+ * module, be sure to call this before re-enabling signals; else handlers
+ * meant to run in the parent process might get invoked in this one.
+ */
+void
+InitializeTimeouts(void)
+{
+	int			i;
+
+	/* Initialize, or re-initialize, all local state */
+	disable_alarm();
+
+	num_active_timeouts = 0;
+
+	for (i = 0; i < MAX_TIMEOUTS; i++)
+	{
+		all_timeouts[i].index = i;
+		all_timeouts[i].active = false;
+		all_timeouts[i].indicator = false;
+		all_timeouts[i].timeout_handler = NULL;
+		all_timeouts[i].start_time = 0;
+		all_timeouts[i].fin_time = 0;
+	}
+
+	all_timeouts_initialized = true;
+
+	/* Now establish the signal handler */
+	pqsignal(SIGALRM, handle_sig_alarm);
+}
+
+/*
+ * Register a timeout reason
+ *
+ * For predefined timeouts, this just registers the callback function.
+ *
+ * For user-defined timeouts, pass id == USER_TIMEOUT; we then allocate and
+ * return a timeout ID.
+ */
+TimeoutId
+RegisterTimeout(TimeoutId id, timeout_handler_proc handler)
+{
+	Assert(all_timeouts_initialized);
+
+	/* There's no need to disable the signal handler here. */
+
+	if (id >= USER_TIMEOUT)
+	{
+		/* Allocate a user-defined timeout reason */
+		for (id = USER_TIMEOUT; id < MAX_TIMEOUTS; id++)
+			if (all_timeouts[id].timeout_handler == NULL)
+				break;
+		if (id >= MAX_TIMEOUTS)
+			ereport(FATAL,
+					(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
+					 errmsg("cannot add more timeout reasons")));
+	}
+
+	Assert(all_timeouts[id].timeout_handler == NULL);
+
+	all_timeouts[id].timeout_handler = handler;
+
+	return id;
+}
+
+/*
+ * Reschedule any pending SIGALRM interrupt.
+ *
+ * This can be used during error recovery in case query cancel resulted in loss
+ * of a SIGALRM event (due to longjmp'ing out of handle_sig_alarm before it
+ * could do anything).  But note it's not necessary if any of the public
+ * enable_ or disable_timeout functions are called in the same area, since
+ * those all do schedule_alarm() internally if needed.
+ */
+void
+reschedule_timeouts(void)
+{
+	/* For flexibility, allow this to be called before we're initialized. */
+	if (!all_timeouts_initialized)
+		return;
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Reschedule the interrupt, if any timeouts remain active. */
+	if (num_active_timeouts > 0)
+		schedule_alarm(GetCurrentTimestamp());
+}
+
+/*
+ * Enable the specified timeout to fire after the specified delay.
+ *
+ * Delay is given in milliseconds.
+ */
+void
+enable_timeout_after(TimeoutId id, int delay_ms)
+{
+	TimestampTz now;
+	TimestampTz fin_time;
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Queue the timeout at the appropriate time. */
+	now = GetCurrentTimestamp();
+	fin_time = TimestampTzPlusMilliseconds(now, delay_ms);
+	enable_timeout(id, now, fin_time);
+
+	/* Set the timer interrupt. */
+	schedule_alarm(now);
+}
+
+/*
+ * Enable the specified timeout to fire at the specified time.
+ *
+ * This is provided to support cases where there's a reason to calculate
+ * the timeout by reference to some point other than "now".  If there isn't,
+ * use enable_timeout_after(), to avoid calling GetCurrentTimestamp() twice.
+ */
+void
+enable_timeout_at(TimeoutId id, TimestampTz fin_time)
+{
+	TimestampTz now;
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Queue the timeout at the appropriate time. */
+	now = GetCurrentTimestamp();
+	enable_timeout(id, now, fin_time);
+
+	/* Set the timer interrupt. */
+	schedule_alarm(now);
+}
+
+/*
+ * Enable multiple timeouts at once.
+ *
+ * This works like calling enable_timeout_after() and/or enable_timeout_at()
+ * multiple times.  Use this to reduce the number of GetCurrentTimestamp()
+ * and setitimer() calls needed to establish multiple timeouts.
+ */
+void
+enable_timeouts(const EnableTimeoutParams *timeouts, int count)
+{
+	TimestampTz now;
+	int			i;
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Queue the timeout(s) at the appropriate times. */
+	now = GetCurrentTimestamp();
+
+	for (i = 0; i < count; i++)
+	{
+		TimeoutId	id = timeouts[i].id;
+		TimestampTz fin_time;
+
+		switch (timeouts[i].type)
+		{
+			case TMPARAM_AFTER:
+				fin_time = TimestampTzPlusMilliseconds(now,
+													   timeouts[i].delay_ms);
+				enable_timeout(id, now, fin_time);
+				break;
+
+			case TMPARAM_AT:
+				enable_timeout(id, now, timeouts[i].fin_time);
+				break;
+
+			default:
+				elog(ERROR, "unrecognized timeout type %d",
+					 (int) timeouts[i].type);
+				break;
+		}
+	}
+
+	/* Set the timer interrupt. */
+	schedule_alarm(now);
+}
+
+/*
+ * Cancel the specified timeout.
+ *
+ * The timeout's I've-been-fired indicator is reset,
+ * unless keep_indicator is true.
+ *
+ * When a timeout is canceled, any other active timeout remains in force.
+ * It's not an error to disable a timeout that is not enabled.
+ */
+void
+disable_timeout(TimeoutId id, bool keep_indicator)
+{
+	/* Assert request is sane */
+	Assert(all_timeouts_initialized);
+	Assert(all_timeouts[id].timeout_handler != NULL);
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Find the timeout and remove it from the active list. */
+	if (all_timeouts[id].active)
+		remove_timeout_index(find_active_timeout(id));
+
+	/* Mark it inactive, whether it was active or not. */
+	if (!keep_indicator)
+		all_timeouts[id].indicator = false;
+
+	/* Reschedule the interrupt, if any timeouts remain active. */
+	if (num_active_timeouts > 0)
+		schedule_alarm(GetCurrentTimestamp());
+}
+
+/*
+ * Cancel multiple timeouts at once.
+ *
+ * The timeouts' I've-been-fired indicators are reset,
+ * unless timeouts[i].keep_indicator is true.
+ *
+ * This works like calling disable_timeout() multiple times.
+ * Use this to reduce the number of GetCurrentTimestamp()
+ * and setitimer() calls needed to cancel multiple timeouts.
+ */
+void
+disable_timeouts(const DisableTimeoutParams *timeouts, int count)
+{
+	int			i;
+
+	Assert(all_timeouts_initialized);
+
+	/* Disable timeout interrupts for safety. */
+	disable_alarm();
+
+	/* Cancel the timeout(s). */
+	for (i = 0; i < count; i++)
+	{
+		TimeoutId	id = timeouts[i].id;
+
+		Assert(all_timeouts[id].timeout_handler != NULL);
+
+		if (all_timeouts[id].active)
+			remove_timeout_index(find_active_timeout(id));
+
+		if (!timeouts[i].keep_indicator)
+			all_timeouts[id].indicator = false;
+	}
+
+	/* Reschedule the interrupt, if any timeouts remain active. */
+	if (num_active_timeouts > 0)
+		schedule_alarm(GetCurrentTimestamp());
+}
+
+/*
+ * Disable the signal handler, remove all timeouts from the active list,
+ * and optionally reset their timeout indicators.
+ */
+void
+disable_all_timeouts(bool keep_indicators)
+{
+	int			i;
+
+	disable_alarm();
+
+	/*
+	 * We used to disable the timer interrupt here, but in common usage
+	 * patterns it's cheaper to leave it enabled; that may save us from having
+	 * to enable it again shortly.  See comments in schedule_alarm().
+	 */
+
+	num_active_timeouts = 0;
+
+	for (i = 0; i < MAX_TIMEOUTS; i++)
+	{
+		all_timeouts[i].active = false;
+		if (!keep_indicators)
+			all_timeouts[i].indicator = false;
+	}
+}
+
+/*
+ * Return true if the timeout is active (enabled and not yet fired)
+ *
+ * This is, of course, subject to race conditions, as the timeout could fire
+ * immediately after we look.
+ */
+bool
+get_timeout_active(TimeoutId id)
+{
+	return all_timeouts[id].active;
+}
+
+/*
+ * Return the timeout's I've-been-fired indicator
+ *
+ * If reset_indicator is true, reset the indicator when returning true.
+ * To avoid missing timeouts due to race conditions, we are careful not to
+ * reset the indicator when returning false.
+ */
+bool
+get_timeout_indicator(TimeoutId id, bool reset_indicator)
+{
+	if (all_timeouts[id].indicator)
+	{
+		if (reset_indicator)
+			all_timeouts[id].indicator = false;
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Return the time when the timeout was most recently activated
+ *
+ * Note: will return 0 if timeout has never been activated in this process.
+ * However, we do *not* reset the start_time when a timeout occurs, so as
+ * not to create a race condition if SIGALRM fires just as some code is
+ * about to fetch the value.
+ */
+TimestampTz
+get_timeout_start_time(TimeoutId id)
+{
+	return all_timeouts[id].start_time;
+}
+
+/*
+ * Return the time when the timeout is, or most recently was, due to fire
+ *
+ * Note: will return 0 if timeout has never been activated in this process.
+ * However, we do *not* reset the fin_time when a timeout occurs, so as
+ * not to create a race condition if SIGALRM fires just as some code is
+ * about to fetch the value.
+ */
+TimestampTz
+get_timeout_finish_time(TimeoutId id)
+{
+	return all_timeouts[id].fin_time;
+}
diff --git a/src/backend/utils/misc/tzparser.c b/src/backend/utils/misc/tzparser.c
new file mode 100644
index 0000000..65e6673
--- /dev/null
+++ b/src/backend/utils/misc/tzparser.c
@@ -0,0 +1,484 @@
+/*-------------------------------------------------------------------------
+ *
+ * tzparser.c
+ *	  Functions for parsing timezone offset files
+ *
+ * Note: this code is invoked from the check_hook for the GUC variable
+ * timezone_abbreviations.  Therefore, it should report problems using
+ * GUC_check_errmsg() and related functions, and try to avoid throwing
+ * elog(ERROR).  This is not completely bulletproof at present --- in
+ * particular out-of-memory will throw an error.  Could probably fix with
+ * PG_TRY if necessary.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/tzparser.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include <ctype.h>
+
+#include "miscadmin.h"
+#include "storage/fd.h"
+#include "utils/guc.h"
+#include "utils/memutils.h"
+#include "utils/tzparser.h"
+
+
+#define WHITESPACE " \t\n\r"
+
+static bool validateTzEntry(tzEntry *tzentry);
+static bool splitTzLine(const char *filename, int lineno,
+						char *line, tzEntry *tzentry);
+static int	addToArray(tzEntry **base, int *arraysize, int n,
+					   tzEntry *entry, bool override);
+static int	ParseTzFile(const char *filename, int depth,
+						tzEntry **base, int *arraysize, int n);
+
+
+/*
+ * Apply additional validation checks to a tzEntry
+ *
+ * Returns true if OK, else false
+ */
+static bool
+validateTzEntry(tzEntry *tzentry)
+{
+	unsigned char *p;
+
+	/*
+	 * Check restrictions imposed by datetktbl storage format (see datetime.c)
+	 */
+	if (strlen(tzentry->abbrev) > TOKMAXLEN)
+	{
+		GUC_check_errmsg("time zone abbreviation \"%s\" is too long (maximum %d characters) in time zone file \"%s\", line %d",
+						 tzentry->abbrev, TOKMAXLEN,
+						 tzentry->filename, tzentry->lineno);
+		return false;
+	}
+
+	/*
+	 * Sanity-check the offset: shouldn't exceed 14 hours
+	 */
+	if (tzentry->offset > 14 * 60 * 60 ||
+		tzentry->offset < -14 * 60 * 60)
+	{
+		GUC_check_errmsg("time zone offset %d is out of range in time zone file \"%s\", line %d",
+						 tzentry->offset,
+						 tzentry->filename, tzentry->lineno);
+		return false;
+	}
+
+	/*
+	 * Convert abbrev to lowercase (must match datetime.c's conversion)
+	 */
+	for (p = (unsigned char *) tzentry->abbrev; *p; p++)
+		*p = pg_tolower(*p);
+
+	return true;
+}
+
+/*
+ * Attempt to parse the line as a timezone abbrev spec
+ *
+ * Valid formats are:
+ *	name  zone
+ *	name  offset  dst
+ *
+ * Returns true if OK, else false; data is stored in *tzentry
+ */
+static bool
+splitTzLine(const char *filename, int lineno, char *line, tzEntry *tzentry)
+{
+	char	   *abbrev;
+	char	   *offset;
+	char	   *offset_endptr;
+	char	   *remain;
+	char	   *is_dst;
+
+	tzentry->lineno = lineno;
+	tzentry->filename = filename;
+
+	abbrev = strtok(line, WHITESPACE);
+	if (!abbrev)
+	{
+		GUC_check_errmsg("missing time zone abbreviation in time zone file \"%s\", line %d",
+						 filename, lineno);
+		return false;
+	}
+	tzentry->abbrev = pstrdup(abbrev);
+
+	offset = strtok(NULL, WHITESPACE);
+	if (!offset)
+	{
+		GUC_check_errmsg("missing time zone offset in time zone file \"%s\", line %d",
+						 filename, lineno);
+		return false;
+	}
+
+	/* We assume zone names don't begin with a digit or sign */
+	if (isdigit((unsigned char) *offset) || *offset == '+' || *offset == '-')
+	{
+		tzentry->zone = NULL;
+		tzentry->offset = strtol(offset, &offset_endptr, 10);
+		if (offset_endptr == offset || *offset_endptr != '\0')
+		{
+			GUC_check_errmsg("invalid number for time zone offset in time zone file \"%s\", line %d",
+							 filename, lineno);
+			return false;
+		}
+
+		is_dst = strtok(NULL, WHITESPACE);
+		if (is_dst && pg_strcasecmp(is_dst, "D") == 0)
+		{
+			tzentry->is_dst = true;
+			remain = strtok(NULL, WHITESPACE);
+		}
+		else
+		{
+			/* there was no 'D' dst specifier */
+			tzentry->is_dst = false;
+			remain = is_dst;
+		}
+	}
+	else
+	{
+		/*
+		 * Assume entry is a zone name.  We do not try to validate it by
+		 * looking up the zone, because that would force loading of a lot of
+		 * zones that probably will never be used in the current session.
+		 */
+		tzentry->zone = pstrdup(offset);
+		tzentry->offset = 0;
+		tzentry->is_dst = false;
+		remain = strtok(NULL, WHITESPACE);
+	}
+
+	if (!remain)				/* no more non-whitespace chars */
+		return true;
+
+	if (remain[0] != '#')		/* must be a comment */
+	{
+		GUC_check_errmsg("invalid syntax in time zone file \"%s\", line %d",
+						 filename, lineno);
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Insert entry into sorted array
+ *
+ * *base: base address of array (changeable if must enlarge array)
+ * *arraysize: allocated length of array (changeable if must enlarge array)
+ * n: current number of valid elements in array
+ * entry: new data to insert
+ * override: true if OK to override
+ *
+ * Returns the new array length (new value for n), or -1 if error
+ */
+static int
+addToArray(tzEntry **base, int *arraysize, int n,
+		   tzEntry *entry, bool override)
+{
+	tzEntry    *arrayptr;
+	int			low;
+	int			high;
+
+	/*
+	 * Search the array for a duplicate; as a useful side effect, the array is
+	 * maintained in sorted order.  We use strcmp() to ensure we match the
+	 * sort order datetime.c expects.
+	 */
+	arrayptr = *base;
+	low = 0;
+	high = n - 1;
+	while (low <= high)
+	{
+		int			mid = (low + high) >> 1;
+		tzEntry    *midptr = arrayptr + mid;
+		int			cmp;
+
+		cmp = strcmp(entry->abbrev, midptr->abbrev);
+		if (cmp < 0)
+			high = mid - 1;
+		else if (cmp > 0)
+			low = mid + 1;
+		else
+		{
+			/*
+			 * Found a duplicate entry; complain unless it's the same.
+			 */
+			if ((midptr->zone == NULL && entry->zone == NULL &&
+				 midptr->offset == entry->offset &&
+				 midptr->is_dst == entry->is_dst) ||
+				(midptr->zone != NULL && entry->zone != NULL &&
+				 strcmp(midptr->zone, entry->zone) == 0))
+			{
+				/* return unchanged array */
+				return n;
+			}
+			if (override)
+			{
+				/* same abbrev but something is different, override */
+				midptr->zone = entry->zone;
+				midptr->offset = entry->offset;
+				midptr->is_dst = entry->is_dst;
+				return n;
+			}
+			/* same abbrev but something is different, complain */
+			GUC_check_errmsg("time zone abbreviation \"%s\" is multiply defined",
+							 entry->abbrev);
+			GUC_check_errdetail("Entry in time zone file \"%s\", line %d, conflicts with entry in file \"%s\", line %d.",
+								midptr->filename, midptr->lineno,
+								entry->filename, entry->lineno);
+			return -1;
+		}
+	}
+
+	/*
+	 * No match, insert at position "low".
+	 */
+	if (n >= *arraysize)
+	{
+		*arraysize *= 2;
+		*base = (tzEntry *) repalloc(*base, *arraysize * sizeof(tzEntry));
+	}
+
+	arrayptr = *base + low;
+
+	memmove(arrayptr + 1, arrayptr, (n - low) * sizeof(tzEntry));
+
+	memcpy(arrayptr, entry, sizeof(tzEntry));
+
+	return n + 1;
+}
+
+/*
+ * Parse a single timezone abbrev file --- can recurse to handle @INCLUDE
+ *
+ * filename: user-specified file name (does not include path)
+ * depth: current recursion depth
+ * *base: array for results (changeable if must enlarge array)
+ * *arraysize: allocated length of array (changeable if must enlarge array)
+ * n: current number of valid elements in array
+ *
+ * Returns the new array length (new value for n), or -1 if error
+ */
+static int
+ParseTzFile(const char *filename, int depth,
+			tzEntry **base, int *arraysize, int n)
+{
+	char		share_path[MAXPGPATH];
+	char		file_path[MAXPGPATH];
+	FILE	   *tzFile;
+	char		tzbuf[1024];
+	char	   *line;
+	tzEntry		tzentry;
+	int			lineno = 0;
+	bool		override = false;
+	const char *p;
+
+	/*
+	 * We enforce that the filename is all alpha characters.  This may be
+	 * overly restrictive, but we don't want to allow access to anything
+	 * outside the timezonesets directory, so for instance '/' *must* be
+	 * rejected.
+	 */
+	for (p = filename; *p; p++)
+	{
+		if (!isalpha((unsigned char) *p))
+		{
+			/* at level 0, just use guc.c's regular "invalid value" message */
+			if (depth > 0)
+				GUC_check_errmsg("invalid time zone file name \"%s\"",
+								 filename);
+			return -1;
+		}
+	}
+
+	/*
+	 * The maximal recursion depth is a pretty arbitrary setting. It is hard
+	 * to imagine that someone needs more than 3 levels so stick with this
+	 * conservative setting until someone complains.
+	 */
+	if (depth > 3)
+	{
+		GUC_check_errmsg("time zone file recursion limit exceeded in file \"%s\"",
+						 filename);
+		return -1;
+	}
+
+	get_share_path(my_exec_path, share_path);
+	snprintf(file_path, sizeof(file_path), "%s/timezonesets/%s",
+			 share_path, filename);
+	tzFile = AllocateFile(file_path, "r");
+	if (!tzFile)
+	{
+		/*
+		 * Check to see if the problem is not the filename but the directory.
+		 * This is worth troubling over because if the installation share/
+		 * directory is missing or unreadable, this is likely to be the first
+		 * place we notice a problem during postmaster startup.
+		 */
+		int			save_errno = errno;
+		DIR		   *tzdir;
+
+		snprintf(file_path, sizeof(file_path), "%s/timezonesets",
+				 share_path);
+		tzdir = AllocateDir(file_path);
+		if (tzdir == NULL)
+		{
+			GUC_check_errmsg("could not open directory \"%s\": %m",
+							 file_path);
+			GUC_check_errhint("This may indicate an incomplete PostgreSQL installation, or that the file \"%s\" has been moved away from its proper location.",
+							  my_exec_path);
+			return -1;
+		}
+		FreeDir(tzdir);
+		errno = save_errno;
+
+		/*
+		 * otherwise, if file doesn't exist and it's level 0, guc.c's
+		 * complaint is enough
+		 */
+		if (errno != ENOENT || depth > 0)
+			GUC_check_errmsg("could not read time zone file \"%s\": %m",
+							 filename);
+
+		return -1;
+	}
+
+	while (!feof(tzFile))
+	{
+		lineno++;
+		if (fgets(tzbuf, sizeof(tzbuf), tzFile) == NULL)
+		{
+			if (ferror(tzFile))
+			{
+				GUC_check_errmsg("could not read time zone file \"%s\": %m",
+								 filename);
+				n = -1;
+				break;
+			}
+			/* else we're at EOF after all */
+			break;
+		}
+		if (strlen(tzbuf) == sizeof(tzbuf) - 1)
+		{
+			/* the line is too long for tzbuf */
+			GUC_check_errmsg("line is too long in time zone file \"%s\", line %d",
+							 filename, lineno);
+			n = -1;
+			break;
+		}
+
+		/* skip over whitespace */
+		line = tzbuf;
+		while (*line && isspace((unsigned char) *line))
+			line++;
+
+		if (*line == '\0')		/* empty line */
+			continue;
+		if (*line == '#')		/* comment line */
+			continue;
+
+		if (pg_strncasecmp(line, "@INCLUDE", strlen("@INCLUDE")) == 0)
+		{
+			/* pstrdup so we can use filename in result data structure */
+			char	   *includeFile = pstrdup(line + strlen("@INCLUDE"));
+
+			includeFile = strtok(includeFile, WHITESPACE);
+			if (!includeFile || !*includeFile)
+			{
+				GUC_check_errmsg("@INCLUDE without file name in time zone file \"%s\", line %d",
+								 filename, lineno);
+				n = -1;
+				break;
+			}
+			n = ParseTzFile(includeFile, depth + 1,
+							base, arraysize, n);
+			if (n < 0)
+				break;
+			continue;
+		}
+
+		if (pg_strncasecmp(line, "@OVERRIDE", strlen("@OVERRIDE")) == 0)
+		{
+			override = true;
+			continue;
+		}
+
+		if (!splitTzLine(filename, lineno, line, &tzentry))
+		{
+			n = -1;
+			break;
+		}
+		if (!validateTzEntry(&tzentry))
+		{
+			n = -1;
+			break;
+		}
+		n = addToArray(base, arraysize, n, &tzentry, override);
+		if (n < 0)
+			break;
+	}
+
+	FreeFile(tzFile);
+
+	return n;
+}
+
+/*
+ * load_tzoffsets --- read and parse the specified timezone offset file
+ *
+ * On success, return a filled-in TimeZoneAbbrevTable, which must have been
+ * malloc'd not palloc'd.  On failure, return NULL, using GUC_check_errmsg
+ * and friends to give details of the problem.
+ */
+TimeZoneAbbrevTable *
+load_tzoffsets(const char *filename)
+{
+	TimeZoneAbbrevTable *result = NULL;
+	MemoryContext tmpContext;
+	MemoryContext oldContext;
+	tzEntry    *array;
+	int			arraysize;
+	int			n;
+
+	/*
+	 * Create a temp memory context to work in.  This makes it easy to clean
+	 * up afterwards.
+	 */
+	tmpContext = AllocSetContextCreate(CurrentMemoryContext,
+									   "TZParserMemory",
+									   ALLOCSET_SMALL_SIZES);
+	oldContext = MemoryContextSwitchTo(tmpContext);
+
+	/* Initialize array at a reasonable size */
+	arraysize = 128;
+	array = (tzEntry *) palloc(arraysize * sizeof(tzEntry));
+
+	/* Parse the file(s) */
+	n = ParseTzFile(filename, 0, &array, &arraysize, 0);
+
+	/* If no errors so far, let datetime.c allocate memory & convert format */
+	if (n >= 0)
+	{
+		result = ConvertTimeZoneAbbrevs(array, n);
+		if (!result)
+			GUC_check_errmsg("out of memory");
+	}
+
+	/* Clean up */
+	MemoryContextSwitchTo(oldContext);
+	MemoryContextDelete(tmpContext);
+
+	return result;
+}