Issue in ExecCleanupTupleRouting()

Hi,

(added Alvaro, Amit, and David)

While working on an update-tuple-routing bug in postgres_fdw [1], I
noticed this change to ExecCleanupTupleRouting() made by commit
3f2393edefa5ef2b6970a5a2fa2c7e9c55cc10cf:

+ /*
+ * Check if this result rel is one belonging to the node's subplans,
+ * if so, let ExecEndPlan() clean it up.
+ */
+ if (htab)
+ {
+ Oid partoid;
+ bool found;
+
+ partoid = RelationGetRelid(resultRelInfo->ri_RelationDesc);
+
+ (void) hash_search(htab, &partoid, HASH_FIND, &found);
+ if (found)
+ continue;
+ }

/* Allow any FDWs to shut down if they've been exercised */
- if (resultRelInfo->ri_PartitionReadyForRouting &&
- resultRelInfo->ri_FdwRoutine != NULL &&
+ if (resultRelInfo->ri_FdwRoutine != NULL &&
resultRelInfo->ri_FdwRoutine->EndForeignInsert != NULL)

resultRelInfo->ri_FdwRoutine->EndForeignInsert(mtstate->ps.state,
resultRelInfo);

This skips subplan resultrels before calling EndForeignInsert() if they
are foreign tables, which I think causes an issue: the FDWs would fail
to release resources for their foreign insert operations, because
ExecEndPlan() and ExecEndModifyTable() don't do anything to allow them
to do that. So I think we should skip subplan resultrels after
EndForeignInsert(). Attached is a small patch for that.

Best regards,
Etsuro Fujita

[1]
https://www.postgresql.org/message-id/21e7eaa4-0d4d-20c2-a1f7-c7e96f4ce440%40lab.ntt.co.jp