I wrote:
> I think we can just delete this assignment (and fix these comments).
As attached. I'm tempted to back-patch this: the plan tree damage
seems harmless at present, but maybe it'd become less harmless with
future fixes.
regards, tom lane
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 46d533b7288..71bc174cfc9 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -4830,12 +4830,11 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
ExprContext *econtext;
/*
- * Initialize result tuple slot and assign its rowtype using the first
- * RETURNING list. We assume the rest will look the same.
+ * Initialize result tuple slot and assign its rowtype using the plan
+ * node's declared targetlist, which the planner set up to be the same
+ * as the first RETURNING list. We assume the rest will produce
+ * compatible output.
*/
- mtstate->ps.plan->targetlist = (List *) linitial(returningLists);
-
- /* Set up a slot for the output of the RETURNING projection(s) */
ExecInitResultTupleSlotTL(&mtstate->ps, &TTSOpsVirtual);
slot = mtstate->ps.ps_ResultTupleSlot;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 150e9f060ee..8e1eb77dd49 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -1097,9 +1097,10 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
/*
* Set up the visible plan targetlist as being the same as
- * the first RETURNING list. This is for the use of
- * EXPLAIN; the executor won't pay any attention to the
- * targetlist. We postpone this step until here so that
+ * the first RETURNING list. This is mostly for the use
+ * of EXPLAIN; the executor won't execute that targetlist,
+ * although it does use it to prepare the node's result
+ * tuple slot. We postpone this step until here so that
* we don't have to do set_returning_clause_references()
* twice on identical targetlists.
*/
