Add ALTER TABLE ENABLE/DISABLE TRIGGER commands. Change pg_dump to

use these instead of its previous hack of changing pg_class.reltriggers.
Documentation is lacking, will add that later.
Patch by Satoshi Nagayasu, review and some extra work by Tom Lane.

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.168 2005/08/22 19:40:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.169 2005/08/23 22:40:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -246,6 +246,8 @@ static void ATExecDropCluster(Relation rel);
 static void ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel,
 					char *tablespacename);
 static void ATExecSetTableSpace(Oid tableOid, Oid newTableSpace);
+static void ATExecEnableDisableTrigger(Relation rel, char *trigname,
+									   bool enable, bool skip_system);
 static void copy_relation_data(Relation rel, SMgrRelation dst);
 static void update_ri_trigger_args(Oid relid,
 					   const char *oldname,
@@ -2005,6 +2007,17 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			ATPrepSetTableSpace(tab, rel, cmd->name);
 			pass = AT_PASS_MISC;	/* doesn't actually matter */
 			break;
+		case AT_EnableTrig:		/* ENABLE TRIGGER variants */
+		case AT_EnableTrigAll:
+		case AT_EnableTrigUser:
+		case AT_DisableTrig:	/* DISABLE TRIGGER variants */
+		case AT_DisableTrigAll:
+		case AT_DisableTrigUser:
+			ATSimplePermissions(rel, false);
+			/* These commands never recurse */
+			/* No command-specific prep needed */
+			pass = AT_PASS_MISC;
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -2163,6 +2176,24 @@ ATExecCmd(AlteredTableInfo *tab, Relation rel, AlterTableCmd *cmd)
 			 * Nothing to do here; Phase 3 does the work
 			 */
 			break;
+		case AT_EnableTrig:		/* ENABLE TRIGGER name */
+			ATExecEnableDisableTrigger(rel, cmd->name, true, false);
+			break;
+		case AT_DisableTrig:	/* DISABLE TRIGGER name */
+			ATExecEnableDisableTrigger(rel, cmd->name, false, false);
+			break;
+		case AT_EnableTrigAll:	/* ENABLE TRIGGER ALL */
+			ATExecEnableDisableTrigger(rel, NULL, true, false);
+			break;
+		case AT_DisableTrigAll:	/* DISABLE TRIGGER ALL */
+			ATExecEnableDisableTrigger(rel, NULL, false, false);
+			break;
+		case AT_EnableTrigUser:	/* ENABLE TRIGGER USER */
+			ATExecEnableDisableTrigger(rel, NULL, true, true);
+			break;
+		case AT_DisableTrigUser: /* DISABLE TRIGGER USER */
+			ATExecEnableDisableTrigger(rel, NULL, false, true);
+			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -5778,6 +5809,18 @@ copy_relation_data(Relation rel, SMgrRelation dst)
 		smgrimmedsync(dst);
 }
 
+/*
+ * ALTER TABLE ENABLE/DISABLE TRIGGER
+ *
+ * We just pass this off to trigger.c.
+ */
+static void
+ATExecEnableDisableTrigger(Relation rel, char *trigname,
+						   bool enable, bool skip_system)
+{
+	EnableDisableTrigger(rel, trigname, enable, skip_system);
+}
+
 /*
  * ALTER TABLE CREATE TOAST TABLE
  *

src/backend/commands/trigger.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.192 2005/08/20 00:39:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.193 2005/08/23 22:40:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -712,6 +712,114 @@ renametrig(Oid relid,
 	heap_close(targetrel, NoLock);
 }
 
+
+/*
+ * EnableDisableTrigger()
+ *
+ *	Called by ALTER TABLE ENABLE/DISABLE TRIGGER
+ *	to change 'tgenabled' flag for the specified trigger(s)
+ *
+ * rel: relation to process (caller must hold suitable lock on it)
+ * tgname: trigger to process, or NULL to scan all triggers
+ * enable: new value for tgenabled flag
+ * skip_system: if true, skip "system" triggers (constraint triggers)
+ *
+ * Caller should have checked permissions for the table; here we also
+ * enforce that superuser privilege is required to alter the state of
+ * system triggers
+ */
+void
+EnableDisableTrigger(Relation rel, const char *tgname,
+					 bool enable, bool skip_system)
+{
+	Relation tgrel;
+	int nkeys;
+	ScanKeyData keys[2];
+	SysScanDesc tgscan;
+	HeapTuple tuple;
+	bool found;
+	bool changed;
+
+	/* Scan the relevant entries in pg_triggers */
+	tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
+
+	ScanKeyInit(&keys[0],
+				Anum_pg_trigger_tgrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(RelationGetRelid(rel)));
+	if (tgname)
+	{
+		ScanKeyInit(&keys[1],
+					Anum_pg_trigger_tgname,
+					BTEqualStrategyNumber, F_NAMEEQ,
+					CStringGetDatum(tgname));
+		nkeys = 2;
+	}
+	else
+		nkeys = 1;
+
+	tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
+								SnapshotNow, nkeys, keys);
+
+	found = changed = false;
+
+	while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
+	{
+		Form_pg_trigger oldtrig = (Form_pg_trigger) GETSTRUCT(tuple);
+
+		if (oldtrig->tgisconstraint)
+		{
+			/* system trigger ... ok to process? */
+			if (skip_system)
+				continue;
+			if (!superuser())
+				ereport(ERROR,
+						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+						 errmsg("permission denied: \"%s\" is a system trigger",
+								NameStr(oldtrig->tgname))));
+		}
+
+		found = true;
+
+		if (oldtrig->tgenabled != enable)
+		{
+			/* need to change this one ... make a copy to scribble on */
+			HeapTuple newtup = heap_copytuple(tuple);
+			Form_pg_trigger newtrig = (Form_pg_trigger) GETSTRUCT(newtup);
+
+			newtrig->tgenabled = enable;
+
+			simple_heap_update(tgrel, &newtup->t_self, newtup);
+
+			/* Keep catalog indexes current */
+			CatalogUpdateIndexes(tgrel, newtup);
+
+			heap_freetuple(newtup);
+
+			changed = true;
+		}
+	}
+
+	systable_endscan(tgscan);
+
+	heap_close(tgrel, RowExclusiveLock);
+
+	if (tgname && !found)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("trigger \"%s\" for table \"%s\" does not exist",
+						tgname, RelationGetRelationName(rel))));
+
+	/*
+	 * If we changed anything, broadcast a SI inval message to force each
+	 * backend (including our own!) to rebuild relation's relcache entry.
+	 * Otherwise they will fail to apply the change promptly.
+	 */
+	if (changed)
+		CacheInvalidateRelcache(rel);
+}
+
+
 /*
  * Build trigger data to attach to the given relcache entry.
  *

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.507 2005/08/01 20:31:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.508 2005/08/23 22:40:20 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -350,9 +350,9 @@ static void doNegateFloat(Value *v);
 
 	DATABASE DAY_P DEALLOCATE DEC DECIMAL_P DECLARE DEFAULT DEFAULTS
 	DEFERRABLE DEFERRED DEFINER DELETE_P DELIMITER DELIMITERS
-	DESC DISTINCT DO DOMAIN_P DOUBLE_P DROP
+	DESC DISABLE_P DISTINCT DO DOMAIN_P DOUBLE_P DROP
 
-	EACH ELSE ENCODING ENCRYPTED END_P ESCAPE EXCEPT EXCLUDING
+	EACH ELSE ENABLE_P ENCODING ENCRYPTED END_P ESCAPE EXCEPT EXCLUDING
 	EXCLUSIVE EXECUTE EXISTS EXPLAIN EXTERNAL EXTRACT
 
 	FALSE_P FETCH FIRST_P FLOAT_P FOR FORCE FOREIGN FORWARD
@@ -1415,6 +1415,50 @@ alter_table_cmd:
 					n->name = NULL;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ENABLE TRIGGER <trig> */
+			| ENABLE_P TRIGGER name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableTrig;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ENABLE TRIGGER ALL */
+			| ENABLE_P TRIGGER ALL
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableTrigAll;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ENABLE TRIGGER USER */
+			| ENABLE_P TRIGGER USER
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableTrigUser;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> DISABLE TRIGGER <trig> */
+			| DISABLE_P TRIGGER name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DisableTrig;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> DISABLE TRIGGER ALL */
+			| DISABLE_P TRIGGER ALL
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DisableTrigAll;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> DISABLE TRIGGER USER */
+			| DISABLE_P TRIGGER USER
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DisableTrigUser;
+					$$ = (Node *)n;
+				}
 			| alter_rel_cmd
 				{
 					$$ = $1;
@@ -8067,10 +8111,12 @@ unreserved_keyword:
 			| DELETE_P
 			| DELIMITER
 			| DELIMITERS
+			| DISABLE_P
 			| DOMAIN_P
 			| DOUBLE_P
 			| DROP
 			| EACH
+			| ENABLE_P
 			| ENCODING
 			| ENCRYPTED
 			| ESCAPE

src/backend/parser/keywords.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.164 2005/07/31 17:19:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.165 2005/08/23 22:40:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -117,6 +117,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"delimiter", DELIMITER},
 	{"delimiters", DELIMITERS},
 	{"desc", DESC},
+	{"disable", DISABLE_P},
 	{"distinct", DISTINCT},
 	{"do", DO},
 	{"domain", DOMAIN_P},
@@ -124,6 +125,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"drop", DROP},
 	{"each", EACH},
 	{"else", ELSE},
+	{"enable", ENABLE_P},
 	{"encoding", ENCODING},
 	{"encrypted", ENCRYPTED},
 	{"end", END_P},