77 * Portions Copyright (c) 1994, Regents of the University of California
88 *
99 * IDENTIFICATION
10- * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.239 2008/11/02 01:45:28 tgl Exp $
10+ * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.240 2008/11/09 21:24:32 tgl Exp $
1111 *
1212 *-------------------------------------------------------------------------
1313 */
@@ -95,7 +95,6 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
9595 Oid funcoid ;
9696 Oid funcrettype ;
9797 Oid trigoid ;
98- int found = 0 ;
9998 int i ;
10099 char constrtrigname [NAMEDATALEN ];
101100 char * trigname ;
@@ -280,10 +279,9 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
280279 }
281280
282281 /*
283- * Scan pg_trigger for existing triggers on relation. We do this mainly
284- * because we must count them; a secondary benefit is to give a nice error
285- * message if there's already a trigger of the same name. (The unique
286- * index on tgrelid/tgname would complain anyway.)
282+ * Scan pg_trigger for existing triggers on relation. We do this only
283+ * to give a nice error message if there's already a trigger of the same
284+ * name. (The unique index on tgrelid/tgname would complain anyway.)
287285 *
288286 * NOTE that this is cool only because we have AccessExclusiveLock on the
289287 * relation, so the trigger set won't be changing underneath us.
@@ -303,7 +301,6 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
303301 (errcode (ERRCODE_DUPLICATE_OBJECT ),
304302 errmsg ("trigger \"%s\" for relation \"%s\" already exists" ,
305303 trigname , stmt -> relation -> relname )));
306- found ++ ;
307304 }
308305 systable_endscan (tgscan );
309306
@@ -405,7 +402,7 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
405402 elog (ERROR , "cache lookup failed for relation %u" ,
406403 RelationGetRelid (rel ));
407404
408- ((Form_pg_class ) GETSTRUCT (tuple ))-> reltriggers = found + 1 ;
405+ ((Form_pg_class ) GETSTRUCT (tuple ))-> relhastriggers = true ;
409406
410407 simple_heap_update (pgrel , & tuple -> t_self , tuple );
411408
@@ -818,9 +815,6 @@ RemoveTriggerById(Oid trigOid)
818815 HeapTuple tup ;
819816 Oid relid ;
820817 Relation rel ;
821- Relation pgrel ;
822- HeapTuple tuple ;
823- Form_pg_class classForm ;
824818
825819 tgrel = heap_open (TriggerRelationId , RowExclusiveLock );
826820
@@ -867,33 +861,15 @@ RemoveTriggerById(Oid trigOid)
867861 heap_close (tgrel , RowExclusiveLock );
868862
869863 /*
870- * Update relation's pg_class entry. Crucial side-effect: other backends
871- * (and this one too!) are sent SI message to make them rebuild relcache
872- * entries.
873- *
874- * Note this is OK only because we have AccessExclusiveLock on the rel, so
875- * no one else is creating/deleting triggers on this rel at the same time.
864+ * We do not bother to try to determine whether any other triggers remain,
865+ * which would be needed in order to decide whether it's safe to clear
866+ * the relation's relhastriggers. (In any case, there might be a
867+ * concurrent process adding new triggers.) Instead, just force a
868+ * relcache inval to make other backends (and this one too!) rebuild
869+ * their relcache entries. There's no great harm in leaving relhastriggers
870+ * true even if there are no triggers left.
876871 */
877- pgrel = heap_open (RelationRelationId , RowExclusiveLock );
878- tuple = SearchSysCacheCopy (RELOID ,
879- ObjectIdGetDatum (relid ),
880- 0 , 0 , 0 );
881- if (!HeapTupleIsValid (tuple ))
882- elog (ERROR , "cache lookup failed for relation %u" , relid );
883- classForm = (Form_pg_class ) GETSTRUCT (tuple );
884-
885- if (classForm -> reltriggers == 0 ) /* should not happen */
886- elog (ERROR , "relation \"%s\" has reltriggers = 0" ,
887- RelationGetRelationName (rel ));
888- classForm -> reltriggers -- ;
889-
890- simple_heap_update (pgrel , & tuple -> t_self , tuple );
891-
892- CatalogUpdateIndexes (pgrel , tuple );
893-
894- heap_freetuple (tuple );
895-
896- heap_close (pgrel , RowExclusiveLock );
872+ CacheInvalidateRelcache (rel );
897873
898874 /* Keep lock on trigger's rel until end of xact */
899875 heap_close (rel , NoLock );
@@ -1134,18 +1110,23 @@ void
11341110RelationBuildTriggers (Relation relation )
11351111{
11361112 TriggerDesc * trigdesc ;
1137- int ntrigs = relation -> rd_rel -> reltriggers ;
1113+ int numtrigs ;
1114+ int maxtrigs ;
11381115 Trigger * triggers ;
1139- int found = 0 ;
11401116 Relation tgrel ;
11411117 ScanKeyData skey ;
11421118 SysScanDesc tgscan ;
11431119 HeapTuple htup ;
11441120 MemoryContext oldContext ;
1121+ int i ;
11451122
1146- Assert (ntrigs > 0 ); /* else I should not have been called */
1147-
1148- triggers = (Trigger * ) palloc (ntrigs * sizeof (Trigger ));
1123+ /*
1124+ * Allocate a working array to hold the triggers (the array is extended
1125+ * if necessary)
1126+ */
1127+ maxtrigs = 16 ;
1128+ triggers = (Trigger * ) palloc (maxtrigs * sizeof (Trigger ));
1129+ numtrigs = 0 ;
11491130
11501131 /*
11511132 * Note: since we scan the triggers using TriggerRelidNameIndexId, we will
@@ -1167,10 +1148,12 @@ RelationBuildTriggers(Relation relation)
11671148 Form_pg_trigger pg_trigger = (Form_pg_trigger ) GETSTRUCT (htup );
11681149 Trigger * build ;
11691150
1170- if (found >= ntrigs )
1171- elog (ERROR , "too many trigger records found for relation \"%s\"" ,
1172- RelationGetRelationName (relation ));
1173- build = & (triggers [found ]);
1151+ if (numtrigs >= maxtrigs )
1152+ {
1153+ maxtrigs *= 2 ;
1154+ triggers = (Trigger * ) repalloc (triggers , maxtrigs * sizeof (Trigger ));
1155+ }
1156+ build = & (triggers [numtrigs ]);
11741157
11751158 build -> tgoid = HeapTupleGetOid (htup );
11761159 build -> tgname = DatumGetCString (DirectFunctionCall1 (nameout ,
@@ -1199,7 +1182,6 @@ RelationBuildTriggers(Relation relation)
11991182 bytea * val ;
12001183 bool isnull ;
12011184 char * p ;
1202- int i ;
12031185
12041186 val = DatumGetByteaP (fastgetattr (htup ,
12051187 Anum_pg_trigger_tgargs ,
@@ -1218,23 +1200,25 @@ RelationBuildTriggers(Relation relation)
12181200 else
12191201 build -> tgargs = NULL ;
12201202
1221- found ++ ;
1203+ numtrigs ++ ;
12221204 }
12231205
12241206 systable_endscan (tgscan );
12251207 heap_close (tgrel , AccessShareLock );
12261208
1227- if (found != ntrigs )
1228- elog (ERROR , "%d trigger record(s) not found for relation \"%s\"" ,
1229- ntrigs - found ,
1230- RelationGetRelationName (relation ));
1209+ /* There might not be any triggers */
1210+ if (numtrigs == 0 )
1211+ {
1212+ pfree (triggers );
1213+ return ;
1214+ }
12311215
12321216 /* Build trigdesc */
12331217 trigdesc = (TriggerDesc * ) palloc0 (sizeof (TriggerDesc ));
12341218 trigdesc -> triggers = triggers ;
1235- trigdesc -> numtriggers = ntrigs ;
1236- for (found = 0 ; found < ntrigs ; found ++ )
1237- InsertTrigger (trigdesc , & (triggers [found ]), found );
1219+ trigdesc -> numtriggers = numtrigs ;
1220+ for (i = 0 ; i < numtrigs ; i ++ )
1221+ InsertTrigger (trigdesc , & (triggers [i ]), i );
12381222
12391223 /* Copy completed trigdesc into cache storage */
12401224 oldContext = MemoryContextSwitchTo (CacheMemoryContext );
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