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

2 files changed, 57 insertions, 5 deletions

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},