Adding upstream version 16.2.upstream/16.2

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

18 files changed, 1348 insertions, 0 deletions

diff --git a/contrib/spi/Makefile b/contrib/spi/Makefile
new file mode 100644
index 0000000..c9c34ff
--- /dev/null
+++ b/contrib/spi/Makefile
@@ -0,0 +1,28 @@
+# contrib/spi/Makefile
+
+MODULES = autoinc insert_username moddatetime refint
+
+EXTENSION = autoinc insert_username moddatetime refint
+
+DATA = autoinc--1.0.sql \
+       insert_username--1.0.sql \
+       moddatetime--1.0.sql \
+       refint--1.0.sql
+PGFILEDESC = "spi - examples of using SPI and triggers"
+
+DOCS = $(addsuffix .example, $(MODULES))
+
+# this is needed for the regression tests;
+# comment out if you want a quieter refint package for other uses
+PG_CPPFLAGS = -DREFINT_VERBOSE
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/spi
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/contrib/spi/autoinc--1.0.sql b/contrib/spi/autoinc--1.0.sql
new file mode 100644
index 0000000..22721e0
--- /dev/null
+++ b/contrib/spi/autoinc--1.0.sql
@@ -0,0 +1,9 @@
+/* contrib/spi/autoinc--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION autoinc" to load this file. \quit
+
+CREATE FUNCTION autoinc()
+RETURNS trigger
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
diff --git a/contrib/spi/autoinc.c b/contrib/spi/autoinc.c
new file mode 100644
index 0000000..8bf7422
--- /dev/null
+++ b/contrib/spi/autoinc.c
@@ -0,0 +1,127 @@
+/*
+ * contrib/spi/autoinc.c
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_type.h"
+#include "commands/sequence.h"
+#include "commands/trigger.h"
+#include "executor/spi.h"
+#include "utils/builtins.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(autoinc);
+
+Datum
+autoinc(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	Trigger    *trigger;		/* to get trigger name */
+	int			nargs;			/* # of arguments */
+	int		   *chattrs;		/* attnums of attributes to change */
+	int			chnattrs = 0;	/* # of above */
+	Datum	   *newvals;		/* vals of above */
+	bool	   *newnulls;		/* null flags for above */
+	char	  **args;			/* arguments */
+	char	   *relname;		/* triggered relation name */
+	Relation	rel;			/* triggered relation */
+	HeapTuple	rettuple = NULL;
+	TupleDesc	tupdesc;		/* tuple description */
+	bool		isnull;
+	int			i;
+
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		/* internal error */
+		elog(ERROR, "not fired by trigger manager");
+	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "must be fired for row");
+	if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "must be fired before event");
+
+	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+		rettuple = trigdata->tg_trigtuple;
+	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
+		rettuple = trigdata->tg_newtuple;
+	else
+		/* internal error */
+		elog(ERROR, "cannot process DELETE events");
+
+	rel = trigdata->tg_relation;
+	relname = SPI_getrelname(rel);
+
+	trigger = trigdata->tg_trigger;
+
+	nargs = trigger->tgnargs;
+	if (nargs <= 0 || nargs % 2 != 0)
+		/* internal error */
+		elog(ERROR, "autoinc (%s): even number gt 0 of arguments was expected", relname);
+
+	args = trigger->tgargs;
+	tupdesc = rel->rd_att;
+
+	chattrs = (int *) palloc(nargs / 2 * sizeof(int));
+	newvals = (Datum *) palloc(nargs / 2 * sizeof(Datum));
+	newnulls = (bool *) palloc(nargs / 2 * sizeof(bool));
+
+	for (i = 0; i < nargs;)
+	{
+		int			attnum = SPI_fnumber(tupdesc, args[i]);
+		int32		val;
+		Datum		seqname;
+
+		if (attnum <= 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+					 errmsg("\"%s\" has no attribute \"%s\"",
+							relname, args[i])));
+
+		if (SPI_gettypeid(tupdesc, attnum) != INT4OID)
+			ereport(ERROR,
+					(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+					 errmsg("attribute \"%s\" of \"%s\" must be type INT4",
+							args[i], relname)));
+
+		val = DatumGetInt32(SPI_getbinval(rettuple, tupdesc, attnum, &isnull));
+
+		if (!isnull && val != 0)
+		{
+			i += 2;
+			continue;
+		}
+
+		i++;
+		chattrs[chnattrs] = attnum;
+		seqname = CStringGetTextDatum(args[i]);
+		newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
+		/* nextval now returns int64; coerce down to int32 */
+		newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
+		if (DatumGetInt32(newvals[chnattrs]) == 0)
+		{
+			newvals[chnattrs] = DirectFunctionCall1(nextval, seqname);
+			newvals[chnattrs] = Int32GetDatum((int32) DatumGetInt64(newvals[chnattrs]));
+		}
+		newnulls[chnattrs] = false;
+		pfree(DatumGetTextPP(seqname));
+		chnattrs++;
+		i++;
+	}
+
+	if (chnattrs > 0)
+	{
+		rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
+											 chnattrs, chattrs,
+											 newvals, newnulls);
+	}
+
+	pfree(relname);
+	pfree(chattrs);
+	pfree(newvals);
+	pfree(newnulls);
+
+	return PointerGetDatum(rettuple);
+}
diff --git a/contrib/spi/autoinc.control b/contrib/spi/autoinc.control
new file mode 100644
index 0000000..1d7a8e5
--- /dev/null
+++ b/contrib/spi/autoinc.control
@@ -0,0 +1,5 @@
+# autoinc extension
+comment = 'functions for autoincrementing fields'
+default_version = '1.0'
+module_pathname = '$libdir/autoinc'
+relocatable = true
diff --git a/contrib/spi/autoinc.example b/contrib/spi/autoinc.example
new file mode 100644
index 0000000..08880ce
--- /dev/null
+++ b/contrib/spi/autoinc.example
@@ -0,0 +1,35 @@
+DROP SEQUENCE next_id;
+DROP TABLE ids;
+
+CREATE SEQUENCE next_id START -2 MINVALUE -2;
+
+CREATE TABLE ids (
+	id		int4,
+	idesc		text
+);
+
+CREATE TRIGGER ids_nextid
+	BEFORE INSERT OR UPDATE ON ids
+	FOR EACH ROW
+	EXECUTE PROCEDURE autoinc (id, next_id);
+
+INSERT INTO ids VALUES (0, 'first (-2 ?)');
+INSERT INTO ids VALUES (null, 'second (-1 ?)');
+INSERT INTO ids(idesc) VALUES ('third (1 ?!)');
+
+SELECT * FROM ids;
+
+UPDATE ids SET id = null, idesc = 'first: -2 --> 2'
+	WHERE idesc = 'first (-2 ?)';
+UPDATE ids SET id = 0, idesc = 'second: -1 --> 3'
+	WHERE id = -1;
+UPDATE ids SET id = 4, idesc = 'third: 1 --> 4'
+	WHERE id = 1;
+
+SELECT * FROM ids;
+
+SELECT 'Wasn''t it 4 ?' as nextval, nextval ('next_id') as value;
+
+insert into ids (idesc) select textcat (idesc, '. Copy.') from ids;
+
+SELECT * FROM ids;
diff --git a/contrib/spi/insert_username--1.0.sql b/contrib/spi/insert_username--1.0.sql
new file mode 100644
index 0000000..0deb0bf
--- /dev/null
+++ b/contrib/spi/insert_username--1.0.sql
@@ -0,0 +1,9 @@
+/* contrib/spi/insert_username--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION insert_username" to load this file. \quit
+
+CREATE FUNCTION insert_username()
+RETURNS trigger
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
diff --git a/contrib/spi/insert_username.c b/contrib/spi/insert_username.c
new file mode 100644
index 0000000..a2e1747
--- /dev/null
+++ b/contrib/spi/insert_username.c
@@ -0,0 +1,92 @@
+/*
+ * contrib/spi/insert_username.c
+ *
+ * insert user name in response to a trigger
+ * usage:  insert_username (column_name)
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_type.h"
+#include "commands/trigger.h"
+#include "executor/spi.h"
+#include "miscadmin.h"
+#include "utils/builtins.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(insert_username);
+
+Datum
+insert_username(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	Trigger    *trigger;		/* to get trigger name */
+	int			nargs;			/* # of arguments */
+	Datum		newval;			/* new value of column */
+	bool		newnull;		/* null flag */
+	char	  **args;			/* arguments */
+	char	   *relname;		/* triggered relation name */
+	Relation	rel;			/* triggered relation */
+	HeapTuple	rettuple = NULL;
+	TupleDesc	tupdesc;		/* tuple description */
+	int			attnum;
+
+	/* sanity checks from autoinc.c */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		/* internal error */
+		elog(ERROR, "insert_username: not fired by trigger manager");
+	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "insert_username: must be fired for row");
+	if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "insert_username: must be fired before event");
+
+	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+		rettuple = trigdata->tg_trigtuple;
+	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
+		rettuple = trigdata->tg_newtuple;
+	else
+		/* internal error */
+		elog(ERROR, "insert_username: cannot process DELETE events");
+
+	rel = trigdata->tg_relation;
+	relname = SPI_getrelname(rel);
+
+	trigger = trigdata->tg_trigger;
+
+	nargs = trigger->tgnargs;
+	if (nargs != 1)
+		/* internal error */
+		elog(ERROR, "insert_username (%s): one argument was expected", relname);
+
+	args = trigger->tgargs;
+	tupdesc = rel->rd_att;
+
+	attnum = SPI_fnumber(tupdesc, args[0]);
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+				 errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));
+
+	if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
+		ereport(ERROR,
+				(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+				 errmsg("attribute \"%s\" of \"%s\" must be type TEXT",
+						args[0], relname)));
+
+	/* create fields containing name */
+	newval = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
+	newnull = false;
+
+	/* construct new tuple */
+	rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
+										 1, &attnum, &newval, &newnull);
+
+	pfree(relname);
+
+	return PointerGetDatum(rettuple);
+}
diff --git a/contrib/spi/insert_username.control b/contrib/spi/insert_username.control
new file mode 100644
index 0000000..9d11064
--- /dev/null
+++ b/contrib/spi/insert_username.control
@@ -0,0 +1,5 @@
+# insert_username extension
+comment = 'functions for tracking who changed a table'
+default_version = '1.0'
+module_pathname = '$libdir/insert_username'
+relocatable = true
diff --git a/contrib/spi/insert_username.example b/contrib/spi/insert_username.example
new file mode 100644
index 0000000..2c1eeb0
--- /dev/null
+++ b/contrib/spi/insert_username.example
@@ -0,0 +1,20 @@
+DROP TABLE username_test;
+
+CREATE TABLE username_test (
+	name		text,
+	username	text not null
+);
+
+CREATE TRIGGER insert_usernames
+	BEFORE INSERT OR UPDATE ON username_test
+	FOR EACH ROW
+	EXECUTE PROCEDURE insert_username (username);
+
+INSERT INTO username_test VALUES ('nothing');
+INSERT INTO username_test VALUES ('null', null);
+INSERT INTO username_test VALUES ('empty string', '');
+INSERT INTO username_test VALUES ('space', ' ');
+INSERT INTO username_test VALUES ('tab', '	');
+INSERT INTO username_test VALUES ('name', 'name');
+
+SELECT * FROM username_test;
diff --git a/contrib/spi/meson.build b/contrib/spi/meson.build
new file mode 100644
index 0000000..a80e2c8
--- /dev/null
+++ b/contrib/spi/meson.build
@@ -0,0 +1,92 @@
+# Copyright (c) 2022-2023, PostgreSQL Global Development Group
+
+autoinc_sources = files(
+  'autoinc.c',
+)
+
+if host_system == 'windows'
+  autoinc_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'autoinc',
+    '--FILEDESC', 'spi - examples of using SPI and triggers',])
+endif
+
+autoinc = shared_module('autoinc',
+  autoinc_sources,
+  kwargs: contrib_mod_args,
+)
+contrib_targets += autoinc
+
+install_data('autoinc.control', 'autoinc--1.0.sql',
+  kwargs: contrib_data_args,
+)
+
+
+insert_username_sources = files(
+  'insert_username.c',
+)
+
+if host_system == 'windows'
+  insert_username_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'insert_username',
+    '--FILEDESC', 'spi - examples of using SPI and triggers',])
+endif
+
+insert_username = shared_module('insert_username',
+  insert_username_sources,
+  kwargs: contrib_mod_args,
+)
+contrib_targets += insert_username
+
+install_data(
+  'insert_username.control',
+  'insert_username--1.0.sql',
+  kwargs: contrib_data_args,
+)
+
+
+moddatetime_sources = files(
+  'moddatetime.c',
+)
+
+if host_system == 'windows'
+  moddatetime_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'moddatetime',
+    '--FILEDESC', 'spi - examples of using SPI and triggers',])
+endif
+
+moddatetime = shared_module('moddatetime',
+  moddatetime_sources,
+  kwargs: contrib_mod_args,
+)
+contrib_targets += moddatetime
+
+install_data(
+  'moddatetime.control',
+  'moddatetime--1.0.sql',
+  kwargs: contrib_data_args,
+)
+
+# this is needed for the regression tests;
+# comment out if you want a quieter refint package for other uses
+refint_cflags = ['-DREFINT_VERBOSE']
+
+refint_sources = files(
+  'refint.c',
+)
+
+if host_system == 'windows'
+  refint_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'refint',
+    '--FILEDESC', 'spi - examples of using SPI and triggers',])
+endif
+
+refint = shared_module('refint',
+  refint_sources,
+  c_args: refint_cflags,
+  kwargs: contrib_mod_args,
+)
+contrib_targets += refint
+
+install_data('refint.control', 'refint--1.0.sql',
+  kwargs: contrib_data_args,
+)
diff --git a/contrib/spi/moddatetime--1.0.sql b/contrib/spi/moddatetime--1.0.sql
new file mode 100644
index 0000000..2ee61b8
--- /dev/null
+++ b/contrib/spi/moddatetime--1.0.sql
@@ -0,0 +1,9 @@
+/* contrib/spi/moddatetime--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION moddatetime" to load this file. \quit
+
+CREATE FUNCTION moddatetime()
+RETURNS trigger
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
diff --git a/contrib/spi/moddatetime.c b/contrib/spi/moddatetime.c
new file mode 100644
index 0000000..3eb7004
--- /dev/null
+++ b/contrib/spi/moddatetime.c
@@ -0,0 +1,130 @@
+/*
+moddatetime.c
+
+contrib/spi/moddatetime.c
+
+What is this?
+It is a function to be called from a trigger for the purpose of updating
+a modification datetime stamp in a record when that record is UPDATEd.
+
+Credits
+This is 95%+ based on autoinc.c, which I used as a starting point as I do
+not really know what I am doing.  I also had help from
+Jan Wieck <jwieck@debis.com> who told me about the timestamp_in("now") function.
+OH, me, I'm Terry Mackintosh <terry@terrym.com>
+*/
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "catalog/pg_type.h"
+#include "commands/trigger.h"
+#include "executor/spi.h"
+#include "utils/builtins.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(moddatetime);
+
+Datum
+moddatetime(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	Trigger    *trigger;		/* to get trigger name */
+	int			nargs;			/* # of arguments */
+	int			attnum;			/* positional number of field to change */
+	Oid			atttypid;		/* type OID of field to change */
+	Datum		newdt;			/* The current datetime. */
+	bool		newdtnull;		/* null flag for it */
+	char	  **args;			/* arguments */
+	char	   *relname;		/* triggered relation name */
+	Relation	rel;			/* triggered relation */
+	HeapTuple	rettuple = NULL;
+	TupleDesc	tupdesc;		/* tuple description */
+
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		/* internal error */
+		elog(ERROR, "moddatetime: not fired by trigger manager");
+
+	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "moddatetime: must be fired for row");
+
+	if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "moddatetime: must be fired before event");
+
+	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "moddatetime: cannot process INSERT events");
+	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
+		rettuple = trigdata->tg_newtuple;
+	else
+		/* internal error */
+		elog(ERROR, "moddatetime: cannot process DELETE events");
+
+	rel = trigdata->tg_relation;
+	relname = SPI_getrelname(rel);
+
+	trigger = trigdata->tg_trigger;
+
+	nargs = trigger->tgnargs;
+
+	if (nargs != 1)
+		/* internal error */
+		elog(ERROR, "moddatetime (%s): A single argument was expected", relname);
+
+	args = trigger->tgargs;
+	/* must be the field layout? */
+	tupdesc = rel->rd_att;
+
+	/*
+	 * This gets the position in the tuple of the field we want. args[0] being
+	 * the name of the field to update, as passed in from the trigger.
+	 */
+	attnum = SPI_fnumber(tupdesc, args[0]);
+
+	/*
+	 * This is where we check to see if the field we are supposed to update
+	 * even exists.
+	 */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+				 errmsg("\"%s\" has no attribute \"%s\"",
+						relname, args[0])));
+
+	/*
+	 * Check the target field has an allowed type, and get the current
+	 * datetime as a value of that type.
+	 */
+	atttypid = SPI_gettypeid(tupdesc, attnum);
+	if (atttypid == TIMESTAMPOID)
+		newdt = DirectFunctionCall3(timestamp_in,
+									CStringGetDatum("now"),
+									ObjectIdGetDatum(InvalidOid),
+									Int32GetDatum(-1));
+	else if (atttypid == TIMESTAMPTZOID)
+		newdt = DirectFunctionCall3(timestamptz_in,
+									CStringGetDatum("now"),
+									ObjectIdGetDatum(InvalidOid),
+									Int32GetDatum(-1));
+	else
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+				 errmsg("attribute \"%s\" of \"%s\" must be type TIMESTAMP or TIMESTAMPTZ",
+						args[0], relname)));
+		newdt = (Datum) 0;		/* keep compiler quiet */
+	}
+	newdtnull = false;
+
+	/* Replace the attnum'th column with newdt */
+	rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
+										 1, &attnum, &newdt, &newdtnull);
+
+	/* Clean up */
+	pfree(relname);
+
+	return PointerGetDatum(rettuple);
+}
diff --git a/contrib/spi/moddatetime.control b/contrib/spi/moddatetime.control
new file mode 100644
index 0000000..93dfac5
--- /dev/null
+++ b/contrib/spi/moddatetime.control
@@ -0,0 +1,5 @@
+# moddatetime extension
+comment = 'functions for tracking last modification time'
+default_version = '1.0'
+module_pathname = '$libdir/moddatetime'
+relocatable = true
diff --git a/contrib/spi/moddatetime.example b/contrib/spi/moddatetime.example
new file mode 100644
index 0000000..65af388
--- /dev/null
+++ b/contrib/spi/moddatetime.example
@@ -0,0 +1,27 @@
+DROP TABLE mdt;
+
+CREATE TABLE mdt (
+	id		int4,
+	idesc		text,
+	moddate timestamp DEFAULT CURRENT_TIMESTAMP NOT NULL
+);
+
+CREATE TRIGGER mdt_moddatetime
+	BEFORE UPDATE ON mdt
+	FOR EACH ROW
+	EXECUTE PROCEDURE moddatetime (moddate);
+
+INSERT INTO mdt VALUES (1, 'first');
+INSERT INTO mdt VALUES (2, 'second');
+INSERT INTO mdt VALUES (3, 'third');
+
+SELECT * FROM mdt;
+
+UPDATE mdt SET id = 4
+	WHERE id = 1;
+UPDATE mdt SET id = 5
+	WHERE id = 2;
+UPDATE mdt SET id = 6
+	WHERE id = 3;
+
+SELECT * FROM mdt;
diff --git a/contrib/spi/refint--1.0.sql b/contrib/spi/refint--1.0.sql
new file mode 100644
index 0000000..faf797c
--- /dev/null
+++ b/contrib/spi/refint--1.0.sql
@@ -0,0 +1,14 @@
+/* contrib/spi/refint--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION refint" to load this file. \quit
+
+CREATE FUNCTION check_primary_key()
+RETURNS trigger
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+CREATE FUNCTION check_foreign_key()
+RETURNS trigger
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
diff --git a/contrib/spi/refint.c b/contrib/spi/refint.c
new file mode 100644
index 0000000..18062eb
--- /dev/null
+++ b/contrib/spi/refint.c
@@ -0,0 +1,654 @@
+/*
+ * contrib/spi/refint.c
+ *
+ *
+ * refint.c --	set of functions to define referential integrity
+ *		constraints using general triggers.
+ */
+#include "postgres.h"
+
+#include <ctype.h>
+
+#include "commands/trigger.h"
+#include "executor/spi.h"
+#include "utils/builtins.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+typedef struct
+{
+	char	   *ident;
+	int			nplans;
+	SPIPlanPtr *splan;
+} EPlan;
+
+static EPlan *FPlans = NULL;
+static int	nFPlans = 0;
+static EPlan *PPlans = NULL;
+static int	nPPlans = 0;
+
+static EPlan *find_plan(char *ident, EPlan **eplan, int *nplans);
+
+/*
+ * check_primary_key () -- check that key in tuple being inserted/updated
+ *			 references existing tuple in "primary" table.
+ * Though it's called without args You have to specify referenced
+ * table/keys while creating trigger:  key field names in triggered table,
+ * referenced table name, referenced key field names:
+ * EXECUTE PROCEDURE
+ * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2').
+ */
+
+PG_FUNCTION_INFO_V1(check_primary_key);
+
+Datum
+check_primary_key(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	Trigger    *trigger;		/* to get trigger name */
+	int			nargs;			/* # of args specified in CREATE TRIGGER */
+	char	  **args;			/* arguments: column names and table name */
+	int			nkeys;			/* # of key columns (= nargs / 2) */
+	Datum	   *kvals;			/* key values */
+	char	   *relname;		/* referenced relation name */
+	Relation	rel;			/* triggered relation */
+	HeapTuple	tuple = NULL;	/* tuple to return */
+	TupleDesc	tupdesc;		/* tuple description */
+	EPlan	   *plan;			/* prepared plan */
+	Oid		   *argtypes = NULL;	/* key types to prepare execution plan */
+	bool		isnull;			/* to know is some column NULL or not */
+	char		ident[2 * NAMEDATALEN]; /* to identify myself */
+	int			ret;
+	int			i;
+
+#ifdef	DEBUG_QUERY
+	elog(DEBUG4, "check_primary_key: Enter Function");
+#endif
+
+	/*
+	 * Some checks first...
+	 */
+
+	/* Called by trigger manager ? */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		/* internal error */
+		elog(ERROR, "check_primary_key: not fired by trigger manager");
+
+	/* Should be called for ROW trigger */
+	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_primary_key: must be fired for row");
+
+	/* If INSERTion then must check Tuple to being inserted */
+	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+		tuple = trigdata->tg_trigtuple;
+
+	/* Not should be called for DELETE */
+	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_primary_key: cannot process DELETE events");
+
+	/* If UPDATE, then must check new Tuple, not old one */
+	else
+		tuple = trigdata->tg_newtuple;
+
+	trigger = trigdata->tg_trigger;
+	nargs = trigger->tgnargs;
+	args = trigger->tgargs;
+
+	if (nargs % 2 != 1)			/* odd number of arguments! */
+		/* internal error */
+		elog(ERROR, "check_primary_key: odd number of arguments should be specified");
+
+	nkeys = nargs / 2;
+	relname = args[nkeys];
+	rel = trigdata->tg_relation;
+	tupdesc = rel->rd_att;
+
+	/* Connect to SPI manager */
+	if ((ret = SPI_connect()) < 0)
+		/* internal error */
+		elog(ERROR, "check_primary_key: SPI_connect returned %d", ret);
+
+	/*
+	 * We use SPI plan preparation feature, so allocate space to place key
+	 * values.
+	 */
+	kvals = (Datum *) palloc(nkeys * sizeof(Datum));
+
+	/*
+	 * Construct ident string as TriggerName $ TriggeredRelationId and try to
+	 * find prepared execution plan.
+	 */
+	snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
+	plan = find_plan(ident, &PPlans, &nPPlans);
+
+	/* if there is no plan then allocate argtypes for preparation */
+	if (plan->nplans <= 0)
+		argtypes = (Oid *) palloc(nkeys * sizeof(Oid));
+
+	/* For each column in key ... */
+	for (i = 0; i < nkeys; i++)
+	{
+		/* get index of column in tuple */
+		int			fnumber = SPI_fnumber(tupdesc, args[i]);
+
+		/* Bad guys may give us un-existing column in CREATE TRIGGER */
+		if (fnumber <= 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("there is no attribute \"%s\" in relation \"%s\"",
+							args[i], SPI_getrelname(rel))));
+
+		/* Well, get binary (in internal format) value of column */
+		kvals[i] = SPI_getbinval(tuple, tupdesc, fnumber, &isnull);
+
+		/*
+		 * If it's NULL then nothing to do! DON'T FORGET call SPI_finish ()!
+		 * DON'T FORGET return tuple! Executor inserts tuple you're returning!
+		 * If you return NULL then nothing will be inserted!
+		 */
+		if (isnull)
+		{
+			SPI_finish();
+			return PointerGetDatum(tuple);
+		}
+
+		if (plan->nplans <= 0)	/* Get typeId of column */
+			argtypes[i] = SPI_gettypeid(tupdesc, fnumber);
+	}
+
+	/*
+	 * If we have to prepare plan ...
+	 */
+	if (plan->nplans <= 0)
+	{
+		SPIPlanPtr	pplan;
+		char		sql[8192];
+
+		/*
+		 * Construct query: SELECT 1 FROM _referenced_relation_ WHERE Pkey1 =
+		 * $1 [AND Pkey2 = $2 [...]]
+		 */
+		snprintf(sql, sizeof(sql), "select 1 from %s where ", relname);
+		for (i = 0; i < nkeys; i++)
+		{
+			snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), "%s = $%d %s",
+					 args[i + nkeys + 1], i + 1, (i < nkeys - 1) ? "and " : "");
+		}
+
+		/* Prepare plan for query */
+		pplan = SPI_prepare(sql, nkeys, argtypes);
+		if (pplan == NULL)
+			/* internal error */
+			elog(ERROR, "check_primary_key: SPI_prepare returned %s", SPI_result_code_string(SPI_result));
+
+		/*
+		 * Remember that SPI_prepare places plan in current memory context -
+		 * so, we have to save plan in TopMemoryContext for later use.
+		 */
+		if (SPI_keepplan(pplan))
+			/* internal error */
+			elog(ERROR, "check_primary_key: SPI_keepplan failed");
+		plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
+														sizeof(SPIPlanPtr));
+		*(plan->splan) = pplan;
+		plan->nplans = 1;
+	}
+
+	/*
+	 * Ok, execute prepared plan.
+	 */
+	ret = SPI_execp(*(plan->splan), kvals, NULL, 1);
+	/* we have no NULLs - so we pass   ^^^^   here */
+
+	if (ret < 0)
+		/* internal error */
+		elog(ERROR, "check_primary_key: SPI_execp returned %d", ret);
+
+	/*
+	 * If there are no tuples returned by SELECT then ...
+	 */
+	if (SPI_processed == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+				 errmsg("tuple references non-existent key"),
+				 errdetail("Trigger \"%s\" found tuple referencing non-existent key in \"%s\".", trigger->tgname, relname)));
+
+	SPI_finish();
+
+	return PointerGetDatum(tuple);
+}
+
+/*
+ * check_foreign_key () -- check that key in tuple being deleted/updated
+ *			 is not referenced by tuples in "foreign" table(s).
+ * Though it's called without args You have to specify (while creating trigger):
+ * number of references, action to do if key referenced
+ * ('restrict' | 'setnull' | 'cascade'), key field names in triggered
+ * ("primary") table and referencing table(s)/keys:
+ * EXECUTE PROCEDURE
+ * check_foreign_key (2, 'restrict', 'Pkey1', 'Pkey2',
+ * 'Ftable1', 'Fkey11', 'Fkey12', 'Ftable2', 'Fkey21', 'Fkey22').
+ */
+
+PG_FUNCTION_INFO_V1(check_foreign_key);
+
+Datum
+check_foreign_key(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	Trigger    *trigger;		/* to get trigger name */
+	int			nargs;			/* # of args specified in CREATE TRIGGER */
+	char	  **args;			/* arguments: as described above */
+	char	  **args_temp;
+	int			nrefs;			/* number of references (== # of plans) */
+	char		action;			/* 'R'estrict | 'S'etnull | 'C'ascade */
+	int			nkeys;			/* # of key columns */
+	Datum	   *kvals;			/* key values */
+	char	   *relname;		/* referencing relation name */
+	Relation	rel;			/* triggered relation */
+	HeapTuple	trigtuple = NULL;	/* tuple to being changed */
+	HeapTuple	newtuple = NULL;	/* tuple to return */
+	TupleDesc	tupdesc;		/* tuple description */
+	EPlan	   *plan;			/* prepared plan(s) */
+	Oid		   *argtypes = NULL;	/* key types to prepare execution plan */
+	bool		isnull;			/* to know is some column NULL or not */
+	bool		isequal = true; /* are keys in both tuples equal (in UPDATE) */
+	char		ident[2 * NAMEDATALEN]; /* to identify myself */
+	int			is_update = 0;
+	int			ret;
+	int			i,
+				r;
+
+#ifdef DEBUG_QUERY
+	elog(DEBUG4, "check_foreign_key: Enter Function");
+#endif
+
+	/*
+	 * Some checks first...
+	 */
+
+	/* Called by trigger manager ? */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		/* internal error */
+		elog(ERROR, "check_foreign_key: not fired by trigger manager");
+
+	/* Should be called for ROW trigger */
+	if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_foreign_key: must be fired for row");
+
+	/* Not should be called for INSERT */
+	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_foreign_key: cannot process INSERT events");
+
+	/* Have to check tg_trigtuple - tuple being deleted */
+	trigtuple = trigdata->tg_trigtuple;
+
+	/*
+	 * But if this is UPDATE then we have to return tg_newtuple. Also, if key
+	 * in tg_newtuple is the same as in tg_trigtuple then nothing to do.
+	 */
+	is_update = 0;
+	if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
+	{
+		newtuple = trigdata->tg_newtuple;
+		is_update = 1;
+	}
+	trigger = trigdata->tg_trigger;
+	nargs = trigger->tgnargs;
+	args = trigger->tgargs;
+
+	if (nargs < 5)				/* nrefs, action, key, Relation, key - at
+								 * least */
+		/* internal error */
+		elog(ERROR, "check_foreign_key: too short %d (< 5) list of arguments", nargs);
+
+	nrefs = pg_strtoint32(args[0]);
+	if (nrefs < 1)
+		/* internal error */
+		elog(ERROR, "check_foreign_key: %d (< 1) number of references specified", nrefs);
+	action = tolower((unsigned char) *(args[1]));
+	if (action != 'r' && action != 'c' && action != 's')
+		/* internal error */
+		elog(ERROR, "check_foreign_key: invalid action %s", args[1]);
+	nargs -= 2;
+	args += 2;
+	nkeys = (nargs - nrefs) / (nrefs + 1);
+	if (nkeys <= 0 || nargs != (nrefs + nkeys * (nrefs + 1)))
+		/* internal error */
+		elog(ERROR, "check_foreign_key: invalid number of arguments %d for %d references",
+			 nargs + 2, nrefs);
+
+	rel = trigdata->tg_relation;
+	tupdesc = rel->rd_att;
+
+	/* Connect to SPI manager */
+	if ((ret = SPI_connect()) < 0)
+		/* internal error */
+		elog(ERROR, "check_foreign_key: SPI_connect returned %d", ret);
+
+	/*
+	 * We use SPI plan preparation feature, so allocate space to place key
+	 * values.
+	 */
+	kvals = (Datum *) palloc(nkeys * sizeof(Datum));
+
+	/*
+	 * Construct ident string as TriggerName $ TriggeredRelationId and try to
+	 * find prepared execution plan(s).
+	 */
+	snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
+	plan = find_plan(ident, &FPlans, &nFPlans);
+
+	/* if there is no plan(s) then allocate argtypes for preparation */
+	if (plan->nplans <= 0)
+		argtypes = (Oid *) palloc(nkeys * sizeof(Oid));
+
+	/*
+	 * else - check that we have exactly nrefs plan(s) ready
+	 */
+	else if (plan->nplans != nrefs)
+		/* internal error */
+		elog(ERROR, "%s: check_foreign_key: # of plans changed in meantime",
+			 trigger->tgname);
+
+	/* For each column in key ... */
+	for (i = 0; i < nkeys; i++)
+	{
+		/* get index of column in tuple */
+		int			fnumber = SPI_fnumber(tupdesc, args[i]);
+
+		/* Bad guys may give us un-existing column in CREATE TRIGGER */
+		if (fnumber <= 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("there is no attribute \"%s\" in relation \"%s\"",
+							args[i], SPI_getrelname(rel))));
+
+		/* Well, get binary (in internal format) value of column */
+		kvals[i] = SPI_getbinval(trigtuple, tupdesc, fnumber, &isnull);
+
+		/*
+		 * If it's NULL then nothing to do! DON'T FORGET call SPI_finish ()!
+		 * DON'T FORGET return tuple! Executor inserts tuple you're returning!
+		 * If you return NULL then nothing will be inserted!
+		 */
+		if (isnull)
+		{
+			SPI_finish();
+			return PointerGetDatum((newtuple == NULL) ? trigtuple : newtuple);
+		}
+
+		/*
+		 * If UPDATE then get column value from new tuple being inserted and
+		 * compare is this the same as old one. For the moment we use string
+		 * presentation of values...
+		 */
+		if (newtuple != NULL)
+		{
+			char	   *oldval = SPI_getvalue(trigtuple, tupdesc, fnumber);
+			char	   *newval;
+
+			/* this shouldn't happen! SPI_ERROR_NOOUTFUNC ? */
+			if (oldval == NULL)
+				/* internal error */
+				elog(ERROR, "check_foreign_key: SPI_getvalue returned %s", SPI_result_code_string(SPI_result));
+			newval = SPI_getvalue(newtuple, tupdesc, fnumber);
+			if (newval == NULL || strcmp(oldval, newval) != 0)
+				isequal = false;
+		}
+
+		if (plan->nplans <= 0)	/* Get typeId of column */
+			argtypes[i] = SPI_gettypeid(tupdesc, fnumber);
+	}
+	args_temp = args;
+	nargs -= nkeys;
+	args += nkeys;
+
+	/*
+	 * If we have to prepare plans ...
+	 */
+	if (plan->nplans <= 0)
+	{
+		SPIPlanPtr	pplan;
+		char		sql[8192];
+		char	  **args2 = args;
+
+		plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
+														nrefs * sizeof(SPIPlanPtr));
+
+		for (r = 0; r < nrefs; r++)
+		{
+			relname = args2[0];
+
+			/*---------
+			 * For 'R'estrict action we construct SELECT query:
+			 *
+			 *	SELECT 1
+			 *	FROM _referencing_relation_
+			 *	WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]]
+			 *
+			 *	to check is tuple referenced or not.
+			 *---------
+			 */
+			if (action == 'r')
+
+				snprintf(sql, sizeof(sql), "select 1 from %s where ", relname);
+
+			/*---------
+			 * For 'C'ascade action we construct DELETE query
+			 *
+			 *	DELETE
+			 *	FROM _referencing_relation_
+			 *	WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]]
+			 *
+			 * to delete all referencing tuples.
+			 *---------
+			 */
+
+			/*
+			 * Max : Cascade with UPDATE query i create update query that
+			 * updates new key values in referenced tables
+			 */
+
+
+			else if (action == 'c')
+			{
+				if (is_update == 1)
+				{
+					int			fn;
+					char	   *nv;
+					int			k;
+
+					snprintf(sql, sizeof(sql), "update %s set ", relname);
+					for (k = 1; k <= nkeys; k++)
+					{
+						int			is_char_type = 0;
+						char	   *type;
+
+						fn = SPI_fnumber(tupdesc, args_temp[k - 1]);
+						Assert(fn > 0); /* already checked above */
+						nv = SPI_getvalue(newtuple, tupdesc, fn);
+						type = SPI_gettype(tupdesc, fn);
+
+						if (strcmp(type, "text") == 0 ||
+							strcmp(type, "varchar") == 0 ||
+							strcmp(type, "char") == 0 ||
+							strcmp(type, "bpchar") == 0 ||
+							strcmp(type, "date") == 0 ||
+							strcmp(type, "timestamp") == 0)
+							is_char_type = 1;
+#ifdef	DEBUG_QUERY
+						elog(DEBUG4, "check_foreign_key Debug value %s type %s %d",
+							 nv, type, is_char_type);
+#endif
+
+						/*
+						 * is_char_type =1 i set ' ' for define a new value
+						 */
+						snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql),
+								 " %s = %s%s%s %s ",
+								 args2[k], (is_char_type > 0) ? "'" : "",
+								 nv, (is_char_type > 0) ? "'" : "", (k < nkeys) ? ", " : "");
+					}
+					strcat(sql, " where ");
+				}
+				else
+					/* DELETE */
+					snprintf(sql, sizeof(sql), "delete from %s where ", relname);
+			}
+
+			/*
+			 * For 'S'etnull action we construct UPDATE query - UPDATE
+			 * _referencing_relation_ SET Fkey1 null [, Fkey2 null [...]]
+			 * WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]] - to set key columns in
+			 * all referencing tuples to NULL.
+			 */
+			else if (action == 's')
+			{
+				snprintf(sql, sizeof(sql), "update %s set ", relname);
+				for (i = 1; i <= nkeys; i++)
+				{
+					snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql),
+							 "%s = null%s",
+							 args2[i], (i < nkeys) ? ", " : "");
+				}
+				strcat(sql, " where ");
+			}
+
+			/* Construct WHERE qual */
+			for (i = 1; i <= nkeys; i++)
+			{
+				snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), "%s = $%d %s",
+						 args2[i], i, (i < nkeys) ? "and " : "");
+			}
+
+			/* Prepare plan for query */
+			pplan = SPI_prepare(sql, nkeys, argtypes);
+			if (pplan == NULL)
+				/* internal error */
+				elog(ERROR, "check_foreign_key: SPI_prepare returned %s", SPI_result_code_string(SPI_result));
+
+			/*
+			 * Remember that SPI_prepare places plan in current memory context
+			 * - so, we have to save plan in Top memory context for later use.
+			 */
+			if (SPI_keepplan(pplan))
+				/* internal error */
+				elog(ERROR, "check_foreign_key: SPI_keepplan failed");
+
+			plan->splan[r] = pplan;
+
+			args2 += nkeys + 1; /* to the next relation */
+		}
+		plan->nplans = nrefs;
+#ifdef	DEBUG_QUERY
+		elog(DEBUG4, "check_foreign_key Debug Query is :  %s ", sql);
+#endif
+	}
+
+	/*
+	 * If UPDATE and key is not changed ...
+	 */
+	if (newtuple != NULL && isequal)
+	{
+		SPI_finish();
+		return PointerGetDatum(newtuple);
+	}
+
+	/*
+	 * Ok, execute prepared plan(s).
+	 */
+	for (r = 0; r < nrefs; r++)
+	{
+		/*
+		 * For 'R'estrict we may to execute plan for one tuple only, for other
+		 * actions - for all tuples.
+		 */
+		int			tcount = (action == 'r') ? 1 : 0;
+
+		relname = args[0];
+
+		snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
+		plan = find_plan(ident, &FPlans, &nFPlans);
+		ret = SPI_execp(plan->splan[r], kvals, NULL, tcount);
+		/* we have no NULLs - so we pass   ^^^^  here */
+
+		if (ret < 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+					 errmsg("SPI_execp returned %d", ret)));
+
+		/* If action is 'R'estrict ... */
+		if (action == 'r')
+		{
+			/* If there is tuple returned by SELECT then ... */
+			if (SPI_processed > 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
+						 errmsg("\"%s\": tuple is referenced in \"%s\"",
+								trigger->tgname, relname)));
+		}
+		else
+		{
+#ifdef REFINT_VERBOSE
+			elog(NOTICE, "%s: " UINT64_FORMAT " tuple(s) of %s are %s",
+				 trigger->tgname, SPI_processed, relname,
+				 (action == 'c') ? "deleted" : "set to null");
+#endif
+		}
+		args += nkeys + 1;		/* to the next relation */
+	}
+
+	SPI_finish();
+
+	return PointerGetDatum((newtuple == NULL) ? trigtuple : newtuple);
+}
+
+static EPlan *
+find_plan(char *ident, EPlan **eplan, int *nplans)
+{
+	EPlan	   *newp;
+	int			i;
+	MemoryContext oldcontext;
+
+	/*
+	 * All allocations done for the plans need to happen in a session-safe
+	 * context.
+	 */
+	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+
+	if (*nplans > 0)
+	{
+		for (i = 0; i < *nplans; i++)
+		{
+			if (strcmp((*eplan)[i].ident, ident) == 0)
+				break;
+		}
+		if (i != *nplans)
+		{
+			MemoryContextSwitchTo(oldcontext);
+			return (*eplan + i);
+		}
+		*eplan = (EPlan *) repalloc(*eplan, (i + 1) * sizeof(EPlan));
+		newp = *eplan + i;
+	}
+	else
+	{
+		newp = *eplan = (EPlan *) palloc(sizeof(EPlan));
+		(*nplans) = i = 0;
+	}
+
+	newp->ident = pstrdup(ident);
+	newp->nplans = 0;
+	newp->splan = NULL;
+	(*nplans)++;
+
+	MemoryContextSwitchTo(oldcontext);
+	return newp;
+}
diff --git a/contrib/spi/refint.control b/contrib/spi/refint.control
new file mode 100644
index 0000000..cbede45
--- /dev/null
+++ b/contrib/spi/refint.control
@@ -0,0 +1,5 @@
+# refint extension
+comment = 'functions for implementing referential integrity (obsolete)'
+default_version = '1.0'
+module_pathname = '$libdir/refint'
+relocatable = true
diff --git a/contrib/spi/refint.example b/contrib/spi/refint.example
new file mode 100644
index 0000000..299166d
--- /dev/null
+++ b/contrib/spi/refint.example
@@ -0,0 +1,82 @@
+--Column ID of table A is primary key:
+
+CREATE TABLE A (
+	ID	int4 not null
+);
+CREATE UNIQUE INDEX AI ON A (ID);
+
+--Columns REFB of table B and REFC of C are foreign keys referencing ID of A:
+
+CREATE TABLE B (
+	REFB	int4
+);
+CREATE INDEX BI ON B (REFB);
+
+CREATE TABLE C (
+	REFC	int4
+);
+CREATE INDEX CI ON C (REFC);
+
+--Trigger for table A:
+
+CREATE TRIGGER AT BEFORE DELETE OR UPDATE ON A FOR EACH ROW
+EXECUTE PROCEDURE
+check_foreign_key (2, 'cascade', 'ID', 'B', 'REFB', 'C', 'REFC');
+/*
+2	- means that check must be performed for foreign keys of 2 tables.
+cascade	- defines that corresponding keys must be deleted.
+ID	- name of primary key column in triggered table (A). You may
+	  use as many columns as you need.
+B	- name of (first) table with foreign keys.
+REFB	- name of foreign key column in this table. You may use as many
+	  columns as you need, but number of key columns in referenced
+	  table (A) must be the same.
+C	- name of second table with foreign keys.
+REFC	- name of foreign key column in this table.
+*/
+
+--Trigger for table B:
+
+CREATE TRIGGER BT BEFORE INSERT OR UPDATE ON B FOR EACH ROW
+EXECUTE PROCEDURE
+check_primary_key ('REFB', 'A', 'ID');
+
+/*
+REFB	- name of foreign key column in triggered (B) table. You may use as
+	  many columns as you need, but number of key columns in referenced
+	  table must be the same.
+A	- referenced table name.
+ID	- name of primary key column in referenced table.
+*/
+
+--Trigger for table C:
+
+CREATE TRIGGER CT BEFORE INSERT OR UPDATE ON C FOR EACH ROW
+EXECUTE PROCEDURE
+check_primary_key ('REFC', 'A', 'ID');
+
+-- Now try
+
+INSERT INTO A VALUES (10);
+INSERT INTO A VALUES (20);
+INSERT INTO A VALUES (30);
+INSERT INTO A VALUES (40);
+INSERT INTO A VALUES (50);
+
+INSERT INTO B VALUES (1);	-- invalid reference
+INSERT INTO B VALUES (10);
+INSERT INTO B VALUES (30);
+INSERT INTO B VALUES (30);
+
+INSERT INTO C VALUES (11);	-- invalid reference
+INSERT INTO C VALUES (20);
+INSERT INTO C VALUES (20);
+INSERT INTO C VALUES (30);
+
+DELETE FROM A WHERE ID = 10;
+DELETE FROM A WHERE ID = 20;
+DELETE FROM A WHERE ID = 30;
+
+SELECT * FROM A;
+SELECT * FROM B;
+SELECT * FROM C;