Add system catalog columns pg_constraint.conindid and pg_trigger.tgconstrindid.

conindid is the index supporting a constraint.  We can use this not only for
unique/primary-key constraints, but also foreign-key constraints, which
depend on the unique index that constrains the referenced columns.
tgconstrindid is just copied from the constraint's conindid field, or is
zero for triggers not associated with constraints.

This is mainly intended as infrastructure for upcoming patches, but it has
some virtue in itself, since it exposes a relationship that you formerly
had to grovel in pg_depend to determine.  I simplified one information_schema
view accordingly.  (There is a pg_dump query that could also use conindid,
but I left it alone because it wasn't clear it'd get any faster.)

1 files changed, 14 insertions, 3 deletions

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index bb628ed80a3..0cc33aae6b6 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 1.248 2009/06/18 01:27:02 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.249 2009/07/28 02:56:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -74,6 +74,9 @@ static void AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event,
  * be made to link the trigger to that constraint.	constraintOid is zero when
  * executing a user-entered CREATE TRIGGER command.
  *
+ * indexOid, if nonzero, is the OID of an index associated with the constraint.
+ * We do nothing with this except store it into pg_trigger.tgconstrindid.
+ *
  * If checkPermissions is true we require ACL_TRIGGER permissions on the
  * relation.  If not, the caller already checked permissions.  (This is
  * currently redundant with constraintOid being zero, but it's clearer to
@@ -83,7 +86,9 @@ static void AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event,
  * but a foreign-key constraint.  This is a kluge for backwards compatibility.
  */
 Oid
-CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid, bool checkPermissions)
+CreateTrigger(CreateTrigStmt *stmt,
+			  Oid constraintOid, Oid indexOid,
+			  bool checkPermissions)
 {
 	int16		tgtype;
 	int2vector *tgattr;
@@ -276,6 +281,7 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid, bool checkPermissions)
 	values[Anum_pg_trigger_tgconstrname - 1] = DirectFunctionCall1(namein,
 												CStringGetDatum(constrname));
 	values[Anum_pg_trigger_tgconstrrelid - 1] = ObjectIdGetDatum(constrrelid);
+	values[Anum_pg_trigger_tgconstrindid - 1] = ObjectIdGetDatum(indexOid);
 	values[Anum_pg_trigger_tgconstraint - 1] = ObjectIdGetDatum(constraintOid);
 	values[Anum_pg_trigger_tgdeferrable - 1] = BoolGetDatum(stmt->deferrable);
 	values[Anum_pg_trigger_tginitdeferred - 1] = BoolGetDatum(stmt->initdeferred);
@@ -410,13 +416,15 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid, bool checkPermissions)
 		referenced.objectId = RelationGetRelid(rel);
 		referenced.objectSubId = 0;
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
-		if (constrrelid != InvalidOid)
+		if (OidIsValid(constrrelid))
 		{
 			referenced.classId = RelationRelationId;
 			referenced.objectId = constrrelid;
 			referenced.objectSubId = 0;
 			recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
 		}
+		/* Not possible to have an index dependency in this case */
+		Assert(!OidIsValid(indexOid));
 	}
 
 	/* Keep lock on target rel until end of xact */
@@ -1122,6 +1130,7 @@ RelationBuildTriggers(Relation relation)
 		build->tgenabled = pg_trigger->tgenabled;
 		build->tgisconstraint = pg_trigger->tgisconstraint;
 		build->tgconstrrelid = pg_trigger->tgconstrrelid;
+		build->tgconstrindid = pg_trigger->tgconstrindid;
 		build->tgconstraint = pg_trigger->tgconstraint;
 		build->tgdeferrable = pg_trigger->tgdeferrable;
 		build->tginitdeferred = pg_trigger->tginitdeferred;
@@ -1467,6 +1476,8 @@ equalTriggerDescs(TriggerDesc *trigdesc1, TriggerDesc *trigdesc2)
 				return false;
 			if (trig1->tgconstrrelid != trig2->tgconstrrelid)
 				return false;
+			if (trig1->tgconstrindid != trig2->tgconstrindid)
+				return false;
 			if (trig1->tgconstraint != trig2->tgconstraint)
 				return false;
 			if (trig1->tgdeferrable != trig2->tgdeferrable)