Fix overlooked relcache invalidation in ALTER TABLE ... ALTER CONSTRAINT.

When altering the deferredness state of a foreign key constraint, we
correctly updated the catalogs and then invalidated the relcache state for
the target relation ... but that's not the only relation with relevant
triggers.  Must invalidate the other table as well, or the state change
fails to take effect promptly for operations triggered on the other table.
Per bug #13224 from Christian Ullrich.

In passing, reorganize regression test case for this feature so that it
isn't randomly injected into the middle of an unrelated test sequence.

Oversight in commit f177cbfe676dc2c7ca2b206c54d6bf819feeea8b.  Back-patch
to 9.4 where the faulty code was added.

1 files changed, 19 insertions, 3 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 5d842857523..299d8ccd81f 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6603,12 +6603,12 @@ static ObjectAddress
 ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
 					  bool recurse, bool recursing, LOCKMODE lockmode)
 {
+	Constraint *cmdcon;
 	Relation	conrel;
 	SysScanDesc scan;
 	ScanKeyData key;
 	HeapTuple	contuple;
 	Form_pg_constraint currcon = NULL;
-	Constraint *cmdcon = NULL;
 	bool		found = false;
 	ObjectAddress address;
 
@@ -6655,10 +6655,11 @@ ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
 		HeapTuple	copyTuple;
 		HeapTuple	tgtuple;
 		Form_pg_constraint copy_con;
-		Form_pg_trigger copy_tg;
+		List	   *otherrelids = NIL;
 		ScanKeyData tgkey;
 		SysScanDesc tgscan;
 		Relation	tgrel;
+		ListCell   *lc;
 
 		/*
 		 * Now update the catalog, while we have the door open.
@@ -6691,8 +6692,16 @@ ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
 
 		while (HeapTupleIsValid(tgtuple = systable_getnext(tgscan)))
 		{
+			Form_pg_trigger copy_tg;
+
 			copyTuple = heap_copytuple(tgtuple);
 			copy_tg = (Form_pg_trigger) GETSTRUCT(copyTuple);
+
+			/* Remember OIDs of other relation(s) involved in FK constraint */
+			if (copy_tg->tgrelid != RelationGetRelid(rel))
+				otherrelids = list_append_unique_oid(otherrelids,
+													 copy_tg->tgrelid);
+
 			copy_tg->tgdeferrable = cmdcon->deferrable;
 			copy_tg->tginitdeferred = cmdcon->initdeferred;
 			simple_heap_update(tgrel, &copyTuple->t_self, copyTuple);
@@ -6709,9 +6718,16 @@ ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
 		heap_close(tgrel, RowExclusiveLock);
 
 		/*
-		 * Invalidate relcache so that others see the new attributes.
+		 * Invalidate relcache so that others see the new attributes.  We must
+		 * inval both the named rel and any others having relevant triggers.
+		 * (At present there should always be exactly one other rel, but
+		 * there's no need to hard-wire such an assumption here.)
 		 */
 		CacheInvalidateRelcache(rel);
+		foreach(lc, otherrelids)
+		{
+			CacheInvalidateRelcacheByRelid(lfirst_oid(lc));
+		}
 
 		ObjectAddressSet(address, ConstraintRelationId,
 						 HeapTupleGetOid(contuple));