Changes pg_trigger and extend pg_rewrite in order to allow triggers and

rules to be defined with different, per session controllable, behaviors
for replication purposes.

This will allow replication systems like Slony-I and, as has been stated
on pgsql-hackers, other products to control the firing mechanism of
triggers and rewrite rules without modifying the system catalog directly.

The firing mechanisms are controlled by a new superuser-only GUC
variable, session_replication_role, together with a change to
pg_trigger.tgenabled and a new column pg_rewrite.ev_enabled. Both
columns are a single char data type now (tgenabled was a bool before).
The possible values in these attributes are:

     'O' - Trigger/Rule fires when session_replication_role is "origin"
           (default) or "local". This is the default behavior.

     'D' - Trigger/Rule is disabled and fires never

     'A' - Trigger/Rule fires always regardless of the setting of
           session_replication_role

     'R' - Trigger/Rule fires when session_replication_role is "replica"

The GUC variable can only be changed as long as the system does not have
any cached query plans. This will prevent changing the session role and
accidentally executing stored procedures or functions that have plans
cached that expand to the wrong query set due to differences in the rule
firing semantics.

The SQL syntax for changing a triggers/rules firing semantics is

     ALTER TABLE <tabname> <when> TRIGGER|RULE <name>;

     <when> ::= ENABLE | ENABLE ALWAYS | ENABLE REPLICA | DISABLE

psql's \d command as well as pg_dump are extended in a backward
compatible fashion.

Jan

10 files changed, 374 insertions, 43 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ddc62086f51..25e53a3dc43 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.217 2007/03/13 00:33:39 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.218 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,7 @@
 #include "parser/parse_relation.h"
 #include "parser/parse_type.h"
 #include "parser/parser.h"
+#include "rewrite/rewriteDefine.h"
 #include "rewrite/rewriteHandler.h"
 #include "storage/smgr.h"
 #include "utils/acl.h"
@@ -253,7 +254,9 @@ static void ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel,
 static void ATExecSetTableSpace(Oid tableOid, Oid newTableSpace);
 static void ATExecSetRelOptions(Relation rel, List *defList, bool isReset);
 static void ATExecEnableDisableTrigger(Relation rel, char *trigname,
-						   bool enable, bool skip_system);
+						   char fires_when, bool skip_system);
+static void ATExecEnableDisableRule(Relation rel, char *rulename,
+						   char fires_when);
 static void ATExecAddInherit(Relation rel, RangeVar *parent);
 static void ATExecDropInherit(Relation rel, RangeVar *parent);
 static void copy_relation_data(Relation rel, SMgrRelation dst);
@@ -1955,11 +1958,17 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_MISC;
 			break;
 		case AT_EnableTrig:		/* ENABLE TRIGGER variants */
+		case AT_EnableAlwaysTrig:
+		case AT_EnableReplicaTrig:
 		case AT_EnableTrigAll:
 		case AT_EnableTrigUser:
 		case AT_DisableTrig:	/* DISABLE TRIGGER variants */
 		case AT_DisableTrigAll:
 		case AT_DisableTrigUser:
+		case AT_EnableRule:		/* ENABLE/DISABLE RULE variants */
+		case AT_EnableAlwaysRule:
+		case AT_EnableReplicaRule:
+		case AT_DisableRule:
 		case AT_AddInherit:		/* INHERIT / NO INHERIT */
 		case AT_DropInherit:
 			ATSimplePermissions(rel, false);
@@ -2127,24 +2136,57 @@ ATExecCmd(AlteredTableInfo *tab, Relation rel, AlterTableCmd *cmd)
 		case AT_ResetRelOptions:		/* RESET (...) */
 			ATExecSetRelOptions(rel, (List *) cmd->def, true);
 			break;
-		case AT_EnableTrig:		/* ENABLE TRIGGER name */
-			ATExecEnableDisableTrigger(rel, cmd->name, true, false);
+
+		case AT_EnableTrig:			/* ENABLE TRIGGER name */
+			ATExecEnableDisableTrigger(rel, cmd->name, 
+					TRIGGER_FIRES_ON_ORIGIN, false);
+			break;
+		case AT_EnableAlwaysTrig:	/* ENABLE ALWAYS TRIGGER name */
+			ATExecEnableDisableTrigger(rel, cmd->name, 
+					TRIGGER_FIRES_ALWAYS, false);
+			break;
+		case AT_EnableReplicaTrig:	/* ENABLE REPLICA TRIGGER name */
+			ATExecEnableDisableTrigger(rel, cmd->name, 
+					TRIGGER_FIRES_ON_REPLICA, false);
 			break;
 		case AT_DisableTrig:	/* DISABLE TRIGGER name */
-			ATExecEnableDisableTrigger(rel, cmd->name, false, false);
+			ATExecEnableDisableTrigger(rel, cmd->name, 
+					TRIGGER_DISABLED, false);
 			break;
 		case AT_EnableTrigAll:	/* ENABLE TRIGGER ALL */
-			ATExecEnableDisableTrigger(rel, NULL, true, false);
+			ATExecEnableDisableTrigger(rel, NULL, 
+					TRIGGER_FIRES_ON_ORIGIN, false);
 			break;
 		case AT_DisableTrigAll:	/* DISABLE TRIGGER ALL */
-			ATExecEnableDisableTrigger(rel, NULL, false, false);
+			ATExecEnableDisableTrigger(rel, NULL, 
+					TRIGGER_DISABLED, false);
 			break;
 		case AT_EnableTrigUser:	/* ENABLE TRIGGER USER */
-			ATExecEnableDisableTrigger(rel, NULL, true, true);
+			ATExecEnableDisableTrigger(rel, NULL, 
+					TRIGGER_FIRES_ON_ORIGIN, true);
 			break;
 		case AT_DisableTrigUser:		/* DISABLE TRIGGER USER */
-			ATExecEnableDisableTrigger(rel, NULL, false, true);
+			ATExecEnableDisableTrigger(rel, NULL, 
+					TRIGGER_DISABLED, true);
+			break;
+
+		case AT_EnableRule:			/* ENABLE RULE name */
+			ATExecEnableDisableRule(rel, cmd->name, 
+					RULE_FIRES_ON_ORIGIN);
+			break;
+		case AT_EnableAlwaysRule:	/* ENABLE ALWAYS RULE name */
+			ATExecEnableDisableRule(rel, cmd->name, 
+					RULE_FIRES_ALWAYS);
+			break;
+		case AT_EnableReplicaRule:	/* ENABLE REPLICA RULE name */
+			ATExecEnableDisableRule(rel, cmd->name, 
+					RULE_FIRES_ON_REPLICA);
+			break;
+		case AT_DisableRule:	/* DISABLE RULE name */
+			ATExecEnableDisableRule(rel, cmd->name, 
+					RULE_DISABLED);
 			break;
+
 		case AT_AddInherit:
 			ATExecAddInherit(rel, (RangeVar *) cmd->def);
 			break;
@@ -4380,7 +4422,7 @@ validateForeignKeyConstraint(FkConstraint *fkconstraint,
 	MemSet(&trig, 0, sizeof(trig));
 	trig.tgoid = InvalidOid;
 	trig.tgname = fkconstraint->constr_name;
-	trig.tgenabled = TRUE;
+	trig.tgenabled = TRIGGER_FIRES_ON_ORIGIN;
 	trig.tgisconstraint = TRUE;
 	trig.tgconstrrelid = RelationGetRelid(pkrel);
 	trig.tgconstraint = constraintOid;
@@ -5877,9 +5919,21 @@ copy_relation_data(Relation rel, SMgrRelation dst)
  */
 static void
 ATExecEnableDisableTrigger(Relation rel, char *trigname,
-						   bool enable, bool skip_system)
+						   char fires_when, bool skip_system)
+{
+	EnableDisableTrigger(rel, trigname, fires_when, skip_system);
+}
+
+/*
+ * ALTER TABLE ENABLE/DISABLE RULE
+ *
+ * We just pass this off to rewriteDefine.c.
+ */
+static void
+ATExecEnableDisableRule(Relation rel, char *trigname,
+						   char fires_when)
 {
-	EnableDisableTrigger(rel, trigname, enable, skip_system);
+	EnableDisableRule(rel, trigname, fires_when);
 }
 
 /*
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index c08525c2e04..e2dadb7a7e2 100644
--- a/src/backend/commands/trigger.c
+++ b/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 1.213 2007/02/14 01:58:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.214 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,6 +54,13 @@ static HeapTuple ExecCallTriggerFunc(TriggerData *trigdata,
 static void AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event,
 					  bool row_trigger, HeapTuple oldtup, HeapTuple newtup);
 
+/*
+ * SessionReplicationRole -
+ *
+ *	Global variable that controls the trigger firing behaviour based
+ *	on pg_trigger.tgenabled. This is maintained from misc/guc.c.
+ */
+int	SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;
 
 /*
  * Create a trigger.  Returns the OID of the created trigger.
@@ -270,7 +277,7 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
 												  CStringGetDatum(trigname));
 	values[Anum_pg_trigger_tgfoid - 1] = ObjectIdGetDatum(funcoid);
 	values[Anum_pg_trigger_tgtype - 1] = Int16GetDatum(tgtype);
-	values[Anum_pg_trigger_tgenabled - 1] = BoolGetDatum(true);
+	values[Anum_pg_trigger_tgenabled - 1] = CharGetDatum(TRIGGER_FIRES_ON_ORIGIN);
 	values[Anum_pg_trigger_tgisconstraint - 1] = BoolGetDatum(stmt->isconstraint);
 	values[Anum_pg_trigger_tgconstrname - 1] = DirectFunctionCall1(namein,
 												CStringGetDatum(constrname));
@@ -701,11 +708,11 @@ renametrig(Oid relid,
  * EnableDisableTrigger()
  *
  *	Called by ALTER TABLE ENABLE/DISABLE TRIGGER
- *	to change 'tgenabled' flag for the specified trigger(s)
+ *	to change 'tgenabled' field 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
+ * enable: new value for tgenabled field
  * skip_system: if true, skip "system" triggers (constraint triggers)
  *
  * Caller should have checked permissions for the table; here we also
@@ -714,7 +721,7 @@ renametrig(Oid relid,
  */
 void
 EnableDisableTrigger(Relation rel, const char *tgname,
-					 bool enable, bool skip_system)
+					 char fires_when, bool skip_system)
 {
 	Relation	tgrel;
 	int			nkeys;
@@ -765,13 +772,13 @@ EnableDisableTrigger(Relation rel, const char *tgname,
 
 		found = true;
 
-		if (oldtrig->tgenabled != enable)
+		if (oldtrig->tgenabled != fires_when)
 		{
 			/* 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;
+			newtrig->tgenabled = fires_when;
 
 			simple_heap_update(tgrel, &newtup->t_self, newtup);
 
@@ -1333,8 +1340,18 @@ ExecBSInsertTriggers(EState *estate, ResultRelInfo *relinfo)
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 		HeapTuple	newtuple;
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigger = trigger;
 		newtuple = ExecCallTriggerFunc(&LocTriggerData,
 									   tgindx[i],
@@ -1382,8 +1399,18 @@ ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
 	{
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigtuple = oldtuple = newtuple;
 		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
 		LocTriggerData.tg_trigger = trigger;
@@ -1444,8 +1471,18 @@ ExecBSDeleteTriggers(EState *estate, ResultRelInfo *relinfo)
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 		HeapTuple	newtuple;
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigger = trigger;
 		newtuple = ExecCallTriggerFunc(&LocTriggerData,
 									   tgindx[i],
@@ -1500,8 +1537,18 @@ ExecBRDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
 	{
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigtuple = trigtuple;
 		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
 		LocTriggerData.tg_trigger = trigger;
@@ -1575,8 +1622,18 @@ ExecBSUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 		HeapTuple	newtuple;
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigger = trigger;
 		newtuple = ExecCallTriggerFunc(&LocTriggerData,
 									   tgindx[i],
@@ -1636,8 +1693,18 @@ ExecBRUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
 	{
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 		LocTriggerData.tg_trigtuple = trigtuple;
 		LocTriggerData.tg_newtuple = oldtuple = newtuple;
 		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
@@ -3267,8 +3334,18 @@ AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event, bool row_trigger,
 		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
 
 		/* Ignore disabled triggers */
-		if (!trigger->tgenabled)
-			continue;
+		if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_ORIGIN ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
+		else /* ORIGIN or LOCAL role */
+		{
+			if (trigger->tgenabled == TRIGGER_FIRES_ON_REPLICA ||
+				trigger->tgenabled == TRIGGER_DISABLED)
+				continue;
+		}
 
 		/*
 		 * If this is an UPDATE of a PK table or FK table that does not change
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 22d03f0b234..75404716d5a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.582 2007/03/17 19:27:12 meskes Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.583 2007/03/19 23:38:29 wieck Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -365,7 +365,7 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
 
 /* ordinary key words in alphabetical order */
 %token <keyword> ABORT_P ABSOLUTE_P ACCESS ACTION ADD_P ADMIN AFTER
-	AGGREGATE ALL ALSO ALTER ANALYSE ANALYZE AND ANY ARRAY AS ASC
+	AGGREGATE ALL ALSO ALTER ALWAYS ANALYSE ANALYZE AND ANY ARRAY AS ASC
 	ASSERTION ASSIGNMENT ASYMMETRIC AT AUTHORIZATION
 
 	BACKWARD BEFORE BEGIN_P BETWEEN BIGINT BINARY BIT
@@ -422,8 +422,8 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
 	QUOTE
 
 	READ REAL REASSIGN RECHECK REFERENCES REINDEX RELATIVE_P RELEASE RENAME
-	REPEATABLE REPLACE RESET RESTART RESTRICT RETURNING RETURNS REVOKE RIGHT
-	ROLE ROLLBACK ROW ROWS RULE
+	REPEATABLE REPLACE REPLICA RESET RESTART RESTRICT RETURNING RETURNS REVOKE
+	RIGHT ROLE ROLLBACK ROW ROWS RULE
 
 	SAVEPOINT SCHEMA SCROLL SECOND_P SECURITY SELECT SEQUENCE
 	SERIALIZABLE SESSION SESSION_USER SET SETOF SHARE
@@ -1480,6 +1480,22 @@ alter_table_cmd:
 					n->name = $3;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ENABLE ALWAYS TRIGGER <trig> */
+			| ENABLE_P ALWAYS TRIGGER name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableAlwaysTrig;
+					n->name = $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ENABLE REPLICA TRIGGER <trig> */
+			| ENABLE_P REPLICA TRIGGER name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableReplicaTrig;
+					n->name = $4;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> ENABLE TRIGGER ALL */
 			| ENABLE_P TRIGGER ALL
 				{
@@ -1516,6 +1532,38 @@ alter_table_cmd:
 					n->subtype = AT_DisableTrigUser;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ENABLE RULE <rule> */
+			| ENABLE_P RULE name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableRule;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ENABLE ALWAYS RULE <rule> */
+			| ENABLE_P ALWAYS RULE name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableAlwaysRule;
+					n->name = $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ENABLE REPLICA RULE <rule> */
+			| ENABLE_P REPLICA RULE name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_EnableReplicaRule;
+					n->name = $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> DISABLE RULE <rule> */
+			| DISABLE_P RULE name
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DisableRule;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> INHERIT <parent> */
 			| INHERIT qualified_name
 				{
@@ -8651,6 +8699,7 @@ unreserved_keyword:
 			| AGGREGATE
 			| ALSO
 			| ALTER
+			| ALWAYS
 			| ASSERTION
 			| ASSIGNMENT
 			| AT
@@ -8796,6 +8845,7 @@ unreserved_keyword:
 			| RENAME
 			| REPEATABLE
 			| REPLACE
+			| REPLICA
 			| RESET
 			| RESTART
 			| RESTRICT
diff --git a/src/backend/parser/keywords.c b/src/backend/parser/keywords.c
index 368f3e06947..9be91e7e6e6 100644
--- a/src/backend/parser/keywords.c
+++ b/src/backend/parser/keywords.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.184 2007/01/25 11:53:51 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.185 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -42,6 +42,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"all", ALL},
 	{"also", ALSO},
 	{"alter", ALTER},
+	{"always", ALWAYS},
 	{"analyse", ANALYSE},		/* British spelling */
 	{"analyze", ANALYZE},
 	{"and", AND},
@@ -289,6 +290,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"rename", RENAME},
 	{"repeatable", REPEATABLE},
 	{"replace", REPLACE},
+	{"replica", REPLICA},
 	{"reset", RESET},
 	{"restart", RESTART},
 	{"restrict", RESTRICT},
diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
index 64a2a96f0e9..864b00f1e73 100644
--- a/src/backend/rewrite/rewriteDefine.c
+++ b/src/backend/rewrite/rewriteDefine.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteDefine.c,v 1.118 2007/03/13 00:33:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteDefine.c,v 1.119 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -30,6 +30,7 @@
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
+#include "utils/inval.h"
 
 
 static void checkRuleResultList(List *targetList, TupleDesc resultDesc,
@@ -79,6 +80,7 @@ InsertRule(char *rulname,
 	values[i++] = ObjectIdGetDatum(eventrel_oid);		/* ev_class */
 	values[i++] = Int16GetDatum(evslot_index);	/* ev_attr */
 	values[i++] = CharGetDatum(evtype + '0');	/* ev_type */
+	values[i++] = CharGetDatum(RULE_FIRES_ON_ORIGIN);	/* ev_enabled */
 	values[i++] = BoolGetDatum(evinstead);		/* is_instead */
 	values[i++] = DirectFunctionCall1(textin, CStringGetDatum(evqual)); /* ev_qual */
 	values[i++] = DirectFunctionCall1(textin, CStringGetDatum(actiontree));		/* ev_action */
@@ -629,6 +631,72 @@ setRuleCheckAsUser_Query(Query *qry, Oid userid)
 
 
 /*
+ * Change the firing semantics of an existing rule.
+ *
+ */
+void
+EnableDisableRule(Relation rel, const char *rulename,
+				  char fires_when)
+{
+	Relation	pg_rewrite_desc;
+	Oid			owningRel = RelationGetRelid(rel);
+	Oid			eventRelationOid;
+	HeapTuple	ruletup;
+	bool		changed = false;
+
+	/*
+	 * Find the rule tuple to change.
+	 */
+	pg_rewrite_desc = heap_open(RewriteRelationId, RowExclusiveLock);
+	ruletup = SearchSysCacheCopy(RULERELNAME,
+								 ObjectIdGetDatum(owningRel),
+								 PointerGetDatum(rulename),
+								 0, 0);
+	if (!HeapTupleIsValid(ruletup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("rule \"%s\" for relation \"%s\" does not exist",
+						rulename, get_rel_name(owningRel))));
+
+	/*
+	 * Verify that the user has appropriate permissions.
+	 */
+	eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_class;
+	Assert(eventRelationOid == owningRel);
+	if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
+						get_rel_name(eventRelationOid));
+	
+	/*
+	 * Change ev_enabled if it is different from the desired new state.
+	 */
+	if (DatumGetChar(((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_enabled) !=
+			fires_when)
+		{
+		((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_enabled =
+					CharGetDatum(fires_when);
+		simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup);
+
+		/* keep system catalog indexes current */
+		CatalogUpdateIndexes(pg_rewrite_desc, ruletup);
+
+		changed = true;
+	}
+
+	heap_freetuple(ruletup);
+	heap_close(pg_rewrite_desc, RowExclusiveLock);
+
+	/*
+	 * 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);
+}
+
+
+/*
  * Rename an existing rewrite rule.
  *
  * This is unused code at the moment.
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index e5a1d4c7472..cd1cb54e9af 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.172 2007/03/17 00:11:04 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.173 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,10 +21,12 @@
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
 #include "parser/parsetree.h"
+#include "rewrite/rewriteDefine.h"
 #include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteManip.h"
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
+#include "commands/trigger.h"
 
 
 /* We use a list of these to detect recursion in RewriteQuery */
@@ -1035,6 +1037,29 @@ matchLocks(CmdType event,
 	{
 		RewriteRule *oneLock = rulelocks->rules[i];
 
+		/*
+		 * Suppress ON INSERT/UPDATE/DELETE rules that are disabled
+		 * or configured to not fire during the current sessions
+		 * replication role. ON SELECT rules will always be applied
+		 * in order to keep views working even in LOCAL or REPLICA
+		 * role.
+		 */
+		if (oneLock->event != CMD_SELECT)
+		{
+			if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
+			{
+				if (oneLock->enabled == RULE_FIRES_ON_ORIGIN ||
+					oneLock->enabled == RULE_DISABLED)
+					continue;
+			}
+			else /* ORIGIN or LOCAL ROLE */
+			{
+				if (oneLock->enabled == RULE_FIRES_ON_REPLICA ||
+					oneLock->enabled == RULE_DISABLED)
+					continue;
+			}
+		}
+
 		if (oneLock->event == event)
 		{
 			if (parsetree->commandType != CMD_SELECT ||
diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c
index 61a576d35d9..4648b05803e 100644
--- a/src/backend/utils/cache/plancache.c
+++ b/src/backend/utils/cache/plancache.c
@@ -33,7 +33,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.2 2007/03/15 23:12:06 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.3 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -860,3 +860,14 @@ InvalRelid(Oid relid, LOCKMODE lockmode, InvalRelidContext *context)
 	if (relid == context->inval_relid)
 		context->plan->dead = true;
 }
+
+/*
+ * HaveCachedPlans 
+ *		Check if the plancache has stored any plans at all.
+ */
+bool
+HaveCachedPlans(void)
+{
+	return (cached_plans_list != NIL);
+}
+
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 4ce955917a5..91b7f146b43 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.257 2007/03/03 20:08:41 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.258 2007/03/19 23:38:29 wieck Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -651,6 +651,7 @@ RelationBuildRuleLock(Relation relation)
 
 		rule->event = rewrite_form->ev_type - '0';
 		rule->attrno = rewrite_form->ev_attr;
+		rule->enabled = rewrite_form->ev_enabled;
 		rule->isInstead = rewrite_form->is_instead;
 
 		/*
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 8088432bac8..f921c75a60b 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.382 2007/03/13 14:32:25 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.383 2007/03/19 23:38:30 wieck Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -34,6 +34,7 @@
 #include "commands/async.h"
 #include "commands/vacuum.h"
 #include "commands/variable.h"
+#include "commands/trigger.h"
 #include "funcapi.h"
 #include "libpq/auth.h"
 #include "libpq/pqformat.h"
@@ -59,6 +60,7 @@
 #include "utils/guc_tables.h"
 #include "utils/memutils.h"
 #include "utils/pg_locale.h"
+#include "utils/plancache.h"
 #include "utils/ps_status.h"
 #include "utils/tzparser.h"
 #include "utils/xml.h"
@@ -124,6 +126,8 @@ static const char *assign_syslog_ident(const char *ident,
 
 static const char *assign_defaultxactisolevel(const char *newval, bool doit,
 						   GucSource source);
+static const char *assign_session_replication_role(const char *newval, bool doit,
+						   GucSource source);
 static const char *assign_log_min_messages(const char *newval, bool doit,
 						GucSource source);
 static const char *assign_client_min_messages(const char *newval,
@@ -226,6 +230,7 @@ static char *backslash_quote_string;
 static char *client_encoding_string;
 static char *datestyle_string;
 static char *default_iso_level_string;
+static char *session_replication_role_string;
 static char *locale_collate;
 static char *locale_ctype;
 static char *regex_flavor_string;
@@ -1929,6 +1934,16 @@ static struct config_string ConfigureNamesString[] =
 	},
 
 	{
+		{"session_replication_role", PGC_SUSET, CLIENT_CONN_STATEMENT,
+			gettext_noop("Sets the sessions behaviour for triggers and rewrite rules."),
+			gettext_noop("Each session can be either"
+						 " \"origin\", \"replica\" or \"local\".")
+		},
+		&session_replication_role_string,
+		"origin", assign_session_replication_role, NULL
+	},
+
+	{
 		{"dynamic_library_path", PGC_SUSET, CLIENT_CONN_OTHER,
 			gettext_noop("Sets the path for dynamically loadable modules."),
 			gettext_noop("If a dynamically loadable module needs to be opened and "
@@ -6116,6 +6131,33 @@ assign_defaultxactisolevel(const char *newval, bool doit, GucSource source)
 }
 
 static const char *
+assign_session_replication_role(const char *newval, bool doit, GucSource source)
+{
+	if (HaveCachedPlans())
+		elog(ERROR, "session_replication_role cannot be changed "
+					"after prepared plans have been cached");
+
+	if (pg_strcasecmp(newval, "origin") == 0)
+	{
+		if (doit)
+			SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;
+	}
+	else if (pg_strcasecmp(newval, "replica") == 0)
+	{
+		if (doit)
+			SessionReplicationRole = SESSION_REPLICATION_ROLE_REPLICA;
+	}
+	else if (pg_strcasecmp(newval, "local") == 0)
+	{
+		if (doit)
+			SessionReplicationRole = SESSION_REPLICATION_ROLE_LOCAL;
+	}
+	else
+		return NULL;
+	return newval;
+}
+
+static const char *
 assign_log_min_messages(const char *newval,
 						bool doit, GucSource source)
 {
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index cf2dfdc099e..22f9685bbdc 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -408,6 +408,7 @@
 #default_transaction_isolation = 'read committed'
 #default_transaction_read_only = off
 #statement_timeout = 0			# 0 is disabled
+#session_replication_role = "origin"
 #vacuum_freeze_min_age = 100000000
 #xmlbinary = 'base64'
 #xmloption = 'content'