Fix incorrect trigger-property updating in ALTER CONSTRAINT.

The code to change the deferrability properties of a foreign-key constraint
updated all the associated triggers to match; but a moment's examination of
the code that creates those triggers in the first place shows that only
some of them should track the constraint's deferrability properties.  This
leads to odd failures in subsequent exercise of the foreign key, as the
triggers are fired at the wrong times.  Fix that, and add a regression test
comparing the trigger properties produced by ALTER CONSTRAINT with those
you get by creating the constraint as-intended to begin with.

Per report from James Parks.  Back-patch to 9.4 where this ALTER
functionality was introduced.

Report: <CAJ3Xv+jzJ8iNNUcp4RKW8b6Qp1xVAxHwSXVpjBNygjKxcVuE9w@mail.gmail.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index f822ed9597e..2137372c234 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6740,16 +6740,34 @@ ATExecAlterConstraint(Relation rel, AlterTableCmd *cmd,
 
 		while (HeapTupleIsValid(tgtuple = systable_getnext(tgscan)))
 		{
+			Form_pg_trigger tgform = (Form_pg_trigger) GETSTRUCT(tgtuple);
 			Form_pg_trigger copy_tg;
 
+			/*
+			 * Remember OIDs of other relation(s) involved in FK constraint.
+			 * (Note: it's likely that we could skip forcing a relcache inval
+			 * for other rels that don't have a trigger whose properties
+			 * change, but let's be conservative.)
+			 */
+			if (tgform->tgrelid != RelationGetRelid(rel))
+				otherrelids = list_append_unique_oid(otherrelids,
+													 tgform->tgrelid);
+
+			/*
+			 * Update deferrability of RI_FKey_noaction_del,
+			 * RI_FKey_noaction_upd, RI_FKey_check_ins and RI_FKey_check_upd
+			 * triggers, but not others; see createForeignKeyTriggers and
+			 * CreateFKCheckTrigger.
+			 */
+			if (tgform->tgfoid != F_RI_FKEY_NOACTION_DEL &&
+				tgform->tgfoid != F_RI_FKEY_NOACTION_UPD &&
+				tgform->tgfoid != F_RI_FKEY_CHECK_INS &&
+				tgform->tgfoid != F_RI_FKEY_CHECK_UPD)
+				continue;
+
 			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);
@@ -7512,6 +7530,9 @@ CreateFKCheckTrigger(Oid myRelOid, Oid refRelOid, Constraint *fkconstraint,
 
 /*
  * Create the triggers that implement an FK constraint.
+ *
+ * NB: if you change any trigger properties here, see also
+ * ATExecAlterConstraint.
  */
 static void
 createForeignKeyTriggers(Relation rel, Oid refRelOid, Constraint *fkconstraint,