Remove obsolete executor cleanup code

This commit removes unnecessary ExecExprFreeContext() calls in
ExecEnd* routines because the actual cleanup is managed by
FreeExecutorState(). With no callers remaining for
ExecExprFreeContext(), this commit also removes the function.

This commit also drops redundant ExecClearTuple() calls, because
ExecResetTupleTable() in ExecEndPlan() already takes care of
resetting and dropping all TupleTableSlots initialized with
ExecInitScanTupleSlot() and ExecInitExtraTupleSlot().

After these modifications, the ExecEnd*() routines for ValuesScan,
NamedTuplestoreScan, and WorkTableScan became redundant. So, this
commit removes them.

Reviewed-by: Robert Haas
Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com

Author: amitlan

src/backend/executor/execProcnode.c

@@ -667,22 +667,10 @@ ExecEndNode(PlanState *node)
 			ExecEndTableFuncScan((TableFuncScanState *) node);
 			break;
 
-		case T_ValuesScanState:
-			ExecEndValuesScan((ValuesScanState *) node);
-			break;
-
 		case T_CteScanState:
 			ExecEndCteScan((CteScanState *) node);
 			break;
 
-		case T_NamedTuplestoreScanState:
-			ExecEndNamedTuplestoreScan((NamedTuplestoreScanState *) node);
-			break;
-
-		case T_WorkTableScanState:
-			ExecEndWorkTableScan((WorkTableScanState *) node);
-			break;
-
 		case T_ForeignScanState:
 			ExecEndForeignScan((ForeignScanState *) node);
 			break;
@@ -757,6 +745,12 @@ ExecEndNode(PlanState *node)
 			ExecEndLimit((LimitState *) node);
 			break;
 
+			/* No clean up actions for these nodes. */
+		case T_ValuesScanState:
+		case T_NamedTuplestoreScanState:
+		case T_WorkTableScanState:
+			break;
+
 		default:
 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
 			break;

src/backend/executor/execUtils.c

@@ -638,32 +638,6 @@ tlist_matches_tupdesc(PlanState *ps, List *tlist, int varno, TupleDesc tupdesc)
 	return true;
 }
 
-/* ----------------
- *		ExecFreeExprContext
- *
- * A plan node's ExprContext should be freed explicitly during executor
- * shutdown because there may be shutdown callbacks to call.  (Other resources
- * made by the above routines, such as projection info, don't need to be freed
- * explicitly because they're just memory in the per-query memory context.)
- *
- * However ... there is no particular need to do it during ExecEndNode,
- * because FreeExecutorState will free any remaining ExprContexts within
- * the EState.  Letting FreeExecutorState do it allows the ExprContexts to
- * be freed in reverse order of creation, rather than order of creation as
- * will happen if we delete them here, which saves O(N^2) work in the list
- * cleanup inside FreeExprContext.
- * ----------------
- */
-void
-ExecFreeExprContext(PlanState *planstate)
-{
-	/*
-	 * Per above discussion, don't actually delete the ExprContext. We do
-	 * unlink it from the plan node, though.
-	 */
-	planstate->ps_ExprContext = NULL;
-}
-
 
 /* ----------------------------------------------------------------
  *				  Scan node support

src/backend/executor/nodeAgg.c

@@ -4357,16 +4357,6 @@ ExecEndAgg(AggState *node)
 	if (node->hashcontext)
 		ReScanExprContext(node->hashcontext);
 
-	/*
-	 * We don't actually free any ExprContexts here (see comment in
-	 * ExecFreeExprContext), just unlinking the output one from the plan node
-	 * suffices.
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* clean up tuple table */
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	outerPlan = outerPlanState(node);
 	ExecEndNode(outerPlan);
 }

src/backend/executor/nodeBitmapHeapscan.c

@@ -655,18 +655,6 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node)
 	 */
 	scanDesc = node->ss.ss_currentScanDesc;
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clear out tuple table slots
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * close down subplans
 	 */

src/backend/executor/nodeBitmapIndexscan.c

@@ -184,14 +184,6 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
 	indexRelationDesc = node->biss_RelationDesc;
 	indexScanDesc = node->biss_ScanDesc;
 
-	/*
-	 * Free the exprcontext ... now dead code, see ExecFreeExprContext
-	 */
-#ifdef NOT_USED
-	if (node->biss_RuntimeContext)
-		FreeExprContext(node->biss_RuntimeContext, true);
-#endif
-
 	/*
 	 * close the index relation (no-op if we didn't open it)
 	 */

src/backend/executor/nodeCtescan.c

@@ -287,18 +287,6 @@ ExecInitCteScan(CteScan *node, EState *estate, int eflags)
 void
 ExecEndCteScan(CteScanState *node)
 {
-	/*
-	 * Free exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * If I am the leader, free the tuplestore.
 	 */

src/backend/executor/nodeCustom.c

@@ -129,13 +129,6 @@ ExecEndCustomScan(CustomScanState *node)
 {
 	Assert(node->methods->EndCustomScan != NULL);
 	node->methods->EndCustomScan(node);
-
-	/* Free the exprcontext */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* Clean out the tuple table */
-	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 void

src/backend/executor/nodeForeignscan.c

@@ -312,14 +312,6 @@ ExecEndForeignScan(ForeignScanState *node)
 	/* Shut down any outer plan. */
 	if (outerPlanState(node))
 		ExecEndNode(outerPlanState(node));
-
-	/* Free the exprcontext */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/* clean out the tuple table */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
 }
 
 /* ----------------------------------------------------------------

src/backend/executor/nodeFunctionscan.c

@@ -523,28 +523,13 @@ ExecEndFunctionScan(FunctionScanState *node)
 {
 	int			i;
 
-	/*
-	 * Free the exprcontext
-	 */
-	ExecFreeExprContext(&node->ss.ps);
-
-	/*
-	 * clean out the tuple table
-	 */
-	if (node->ss.ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
-	ExecClearTuple(node->ss.ss_ScanTupleSlot);
-
 	/*
 	 * Release slots and tuplestore resources
 	 */
 	for (i = 0; i < node->nfuncs; i++)
 	{
 		FunctionScanPerFuncState *fs = &node->funcstates[i];
 
-		if (fs->func_slot)
-			ExecClearTuple(fs->func_slot);
-
 		if (fs->tstore != NULL)
 		{
 			tuplestore_end(node->funcstates[i].tstore);

src/backend/executor/nodeGather.c

@@ -250,9 +250,6 @@ ExecEndGather(GatherState *node)
 {
 	ExecEndNode(outerPlanState(node));	/* let children clean up first */
 	ExecShutdownGather(node);
-	ExecFreeExprContext(&node->ps);
-	if (node->ps.ps_ResultTupleSlot)
-		ExecClearTuple(node->ps.ps_ResultTupleSlot);
 }
 
 /*