Disallow collecting transition tuples from child foreign tables.

Commit 9e6104c66 disallowed transition tables on foreign tables, but
failed to account for cases where a foreign table is a child table of a
partitioned/inherited table on which transition tables exist, leading to
incorrect transition tuples collected from such foreign tables for
queries on the parent table triggering transition capture.  This
occurred not only for inherited UPDATE/DELETE but for partitioned INSERT
later supported by commit 3d956d956, which should have handled it at
least for the INSERT case, but didn't.

To fix, modify ExecAR*Triggers to throw an error if the given relation
is a foreign table requesting transition capture.  Also, this commit
fixes make_modifytable so that in case of an inherited UPDATE/DELETE
triggering transition capture, FDWs choose normal operations to modify
child foreign tables, not DirectModify; which is needed because they
would otherwise skip the calls to ExecAR*Triggers at execution, causing
unexpected behavior.

Author: Etsuro Fujita <etsuro.fujita@gmail.com>
Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CAPmGK14QJYikKzBDCe3jMbpGENnQ7popFmbEgm-XTNuk55oyHg%40mail.gmail.com
Backpatch-through: 13

1 files changed, 20 insertions, 4 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index bfefc7dbea1..9fd5c31edf2 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -7233,6 +7233,8 @@ make_modifytable(PlannerInfo *root, Plan *subplan,
 	ModifyTable *node = makeNode(ModifyTable);
 	bool		returning_old_or_new = false;
 	bool		returning_old_or_new_valid = false;
+	bool		transition_tables = false;
+	bool		transition_tables_valid = false;
 	List	   *fdw_private_list;
 	Bitmapset  *direct_modify_plans;
 	ListCell   *lc;
@@ -7379,8 +7381,8 @@ make_modifytable(PlannerInfo *root, Plan *subplan,
 		 * callback functions needed for that and (2) there are no local
 		 * structures that need to be run for each modified row: row-level
 		 * triggers on the foreign table, stored generated columns, WITH CHECK
-		 * OPTIONs from parent views, or Vars returning OLD/NEW in the
-		 * RETURNING list.
+		 * OPTIONs from parent views, Vars returning OLD/NEW in the RETURNING
+		 * list, or transition tables on the named relation.
 		 */
 		direct_modify = false;
 		if (fdwroutine != NULL &&
@@ -7392,7 +7394,10 @@ make_modifytable(PlannerInfo *root, Plan *subplan,
 			!has_row_triggers(root, rti, operation) &&
 			!has_stored_generated_columns(root, rti))
 		{
-			/* returning_old_or_new is the same for all result relations */
+			/*
+			 * returning_old_or_new and transition_tables are the same for all
+			 * result relations, respectively
+			 */
 			if (!returning_old_or_new_valid)
 			{
 				returning_old_or_new =
@@ -7401,7 +7406,18 @@ make_modifytable(PlannerInfo *root, Plan *subplan,
 				returning_old_or_new_valid = true;
 			}
 			if (!returning_old_or_new)
-				direct_modify = fdwroutine->PlanDirectModify(root, node, rti, i);
+			{
+				if (!transition_tables_valid)
+				{
+					transition_tables = has_transition_tables(root,
+															  nominalRelation,
+															  operation);
+					transition_tables_valid = true;
+				}
+				if (!transition_tables)
+					direct_modify = fdwroutine->PlanDirectModify(root, node,
+																 rti, i);
+			}
 		}
 		if (direct_modify)
 			direct_modify_plans = bms_add_member(direct_modify_plans, i);