diff options
Diffstat (limited to 'src/backend/utils/adt')
| -rw-r--r-- | src/backend/utils/adt/Makefile | 4 | ||||
| -rw-r--r-- | src/backend/utils/adt/trigfuncs.c | 77 |
2 files changed, 79 insertions, 2 deletions
diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile index 991684a3331..d7d28c9f159 100644 --- a/src/backend/utils/adt/Makefile +++ b/src/backend/utils/adt/Makefile @@ -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 \ diff --git a/src/backend/utils/adt/trigfuncs.c b/src/backend/utils/adt/trigfuncs.c new file mode 100644 index 00000000000..2f3692ec431 --- /dev/null +++ b/src/backend/utils/adt/trigfuncs.c @@ -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); +} |