Adding upstream version 14.5.upstream/14.5upstream

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

1 files changed, 12546 insertions, 0 deletions

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"