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suppress_redundant_updates_trigger function.

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This commit is contained in:
Andrew Dunstan
2008-11-03 20:17:21 +00:00
parent 4ff0468371
commit f0dae70431
7 changed files with 194 additions and 5 deletions
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4
src/backend/utils/adt/Makefile
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@ -1,7 +1,7 @@
#
# Makefile for utils/adt
#
# $PostgreSQL: pgsql/src/backend/utils/adt/Makefile,v 1.69 2008/02/19 10:30:08 petere Exp $
# $PostgreSQL: pgsql/src/backend/utils/adt/Makefile,v 1.70 2008/11/03 20:17:20 adunstan Exp $
#
subdir = src/backend/utils/adt
@ -25,7 +25,7 @@ OBJS = acl.o arrayfuncs.o array_userfuncs.o arrayutils.o bool.o \
tid.o timestamp.o varbit.o varchar.o varlena.o version.o xid.o \
network.o mac.o inet_net_ntop.o inet_net_pton.o \
ri_triggers.o pg_lzcompress.o pg_locale.o formatting.o \
ascii.o quote.o pgstatfuncs.o encode.o dbsize.o genfile.o \
ascii.o quote.o pgstatfuncs.o encode.o dbsize.o genfile.o trigfuncs.o \
tsginidx.o tsgistidx.o tsquery.o tsquery_cleanup.o tsquery_gist.o \
tsquery_op.o tsquery_rewrite.o tsquery_util.o tsrank.o \
tsvector.o tsvector_op.o tsvector_parser.o \

77
src/backend/utils/adt/trigfuncs.c Normal file
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@ -0,0 +1,77 @@
/*-------------------------------------------------------------------------
*
* trigfuncs.c
* Builtin functions for useful trigger support.
*
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/utils/adt/trigfuncs.c,v 1.1 2008/11/03 20:17:20 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "commands/trigger.h"
#include "access/htup.h"
/*
* suppress_redundant_updates_trigger
*
* This trigger function will inhibit an update from being done
* if the OLD and NEW records are identical.
*
*/
Datum
suppress_redundant_updates_trigger(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
HeapTuple newtuple, oldtuple, rettuple;
HeapTupleHeader newheader, oldheader;
/* make sure it's called as a trigger */
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("suppress_redundant_updates_trigger: must be called as trigger")));
/* and that it's called on update */
if (! TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
ereport(ERROR, (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg( "suppress_redundant_updates_trigger: may only be called on update")));
/* and that it's called before update */
if (! TRIGGER_FIRED_BEFORE(trigdata->tg_event))
ereport(ERROR, (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg( "suppress_redundant_updates_trigger: may only be called before update")));
/* and that it's called for each row */
if (! TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
ereport(ERROR, (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg( "suppress_redundant_updates_trigger: may only be called for each row")));
/* get tuple data, set default return */
rettuple = newtuple = trigdata->tg_newtuple;
oldtuple = trigdata->tg_trigtuple;
newheader = newtuple->t_data;
oldheader = oldtuple->t_data;
if (newtuple->t_len == oldtuple->t_len &&
newheader->t_hoff == oldheader->t_hoff &&
(HeapTupleHeaderGetNatts(newheader) ==
HeapTupleHeaderGetNatts(oldheader) ) &&
((newheader->t_infomask & ~HEAP_XACT_MASK) ==
(oldheader->t_infomask & ~HEAP_XACT_MASK) )&&
memcmp(((char *)newheader) + offsetof(HeapTupleHeaderData, t_bits),
((char *)oldheader) + offsetof(HeapTupleHeaderData, t_bits),
newtuple->t_len - offsetof(HeapTupleHeaderData, t_bits)) == 0)
{
rettuple = NULL;
}
return PointerGetDatum(rettuple);
}

6
src/include/catalog/pg_proc.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.521 2008/11/03 17:51:13 tgl Exp $
* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.522 2008/11/03 20:17:20 adunstan Exp $
*
* NOTES
* The script catalog/genbki.sh reads this file and generates .bki
@ -1580,6 +1580,9 @@ DESCR("convert int8 to oid");
DATA(insert OID = 1288 ( int8 PGNSP PGUID 12 1 0 0 f f t f i 1 20 "26" _null_ _null_ _null_ oidtoi8 _null_ _null_ _null_ ));
DESCR("convert oid to int8");
DATA(insert OID = 1291 ( suppress_redundant_updates_trigger PGNSP PGUID 12 1 0 0 f f t f v 0 2279 "" _null_ _null_ _null_ suppress_redundant_updates_trigger _null_ _null_ _null_ ));
DESCR("trigger to suppress updates when new and old records match");
DATA(insert OID = 1292 ( tideq PGNSP PGUID 12 1 0 0 f f t f i 2 16 "27 27" _null_ _null_ _null_ tideq _null_ _null_ _null_ ));
DESCR("equal");
DATA(insert OID = 1293 ( currtid PGNSP PGUID 12 1 0 0 f f t f v 2 27 "26 27" _null_ _null_ _null_ currtid_byreloid _null_ _null_ _null_ ));
@ -2289,6 +2292,7 @@ DESCR("result type of a function");
DATA(insert OID = 1686 ( pg_get_keywords PGNSP PGUID 12 10 400 0 f f t t s 0 2249 "" "{25,18,25}" "{o,o,o}" "{word,catcode,catdesc}" pg_get_keywords _null_ _null_ _null_ ));
DESCR("list of SQL keywords");
DATA(insert OID = 1619 ( pg_typeof PGNSP PGUID 12 1 0 0 f f f f i 1 2206 "2276" _null_ _null_ _null_ pg_typeof _null_ _null_ _null_ ));
DESCR("returns the type of the argument");

5
src/include/utils/builtins.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.325 2008/11/03 17:51:13 tgl Exp $
* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.326 2008/11/03 20:17:20 adunstan Exp $
*
*-------------------------------------------------------------------------
*/
@ -900,6 +900,9 @@ extern Datum RI_FKey_setnull_upd(PG_FUNCTION_ARGS);
extern Datum RI_FKey_setdefault_del(PG_FUNCTION_ARGS);
extern Datum RI_FKey_setdefault_upd(PG_FUNCTION_ARGS);
/* trigfuncs.c */
extern Datum suppress_redundant_updates_trigger(PG_FUNCTION_ARGS);
/* encoding support functions */
extern Datum getdatabaseencoding(PG_FUNCTION_ARGS);
extern Datum database_character_set(PG_FUNCTION_ARGS);

25
src/test/regress/expected/triggers.out
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@ -537,3 +537,28 @@ NOTICE: row 1 not changed
NOTICE: row 2 not changed
DROP TABLE trigger_test;
DROP FUNCTION mytrigger();
-- minimal update trigger
CREATE TABLE min_updates_test (
f1 text,
f2 int,
f3 int);
INSERT INTO min_updates_test VALUES ('a',1,2),('b','2',null);
CREATE TRIGGER z_min_update
BEFORE UPDATE ON min_updates_test
FOR EACH ROW EXECUTE PROCEDURE suppress_redundant_updates_trigger();
\set QUIET false
UPDATE min_updates_test SET f1 = f1;
UPDATE 0
UPDATE min_updates_test SET f2 = f2 + 1;
UPDATE 2
UPDATE min_updates_test SET f3 = 2 WHERE f3 is null;
UPDATE 1
\set QUIET true
SELECT * FROM min_updates_test;
f1 | f2 | f3
----+----+----
a | 2 | 2
b | 3 | 2
(2 rows)
DROP TABLE min_updates_test;

29
src/test/regress/sql/triggers.sql
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@ -415,3 +415,32 @@ UPDATE trigger_test SET f3 = NULL;
DROP TABLE trigger_test;
DROP FUNCTION mytrigger();
-- minimal update trigger
CREATE TABLE min_updates_test (
f1 text,
f2 int,
f3 int);
INSERT INTO min_updates_test VALUES ('a',1,2),('b','2',null);
CREATE TRIGGER z_min_update
BEFORE UPDATE ON min_updates_test
FOR EACH ROW EXECUTE PROCEDURE suppress_redundant_updates_trigger();
\set QUIET false
UPDATE min_updates_test SET f1 = f1;
UPDATE min_updates_test SET f2 = f2 + 1;
UPDATE min_updates_test SET f3 = 2 WHERE f3 is null;
\set QUIET true
SELECT * FROM min_updates_test;
DROP TABLE min_updates_test;