Allow tupleslots to have a fixed tupledesc, use in executor nodes.

The reason for doing so is that it will allow expression evaluation to
optimize based on the underlying tupledesc. In particular it will
allow to JIT tuple deforming together with the expression itself.

For that expression initialization needs to be moved after the
relevant slots are initialized - mostly unproblematic, except in the
case of nodeWorktablescan.c.

After doing so there's no need for ExecAssignResultType() and
ExecAssignResultTypeFromTL() anymore, as all former callers have been
converted to create a slot with a fixed descriptor.

When creating a slot with a fixed descriptor, tts_values/isnull can be
allocated together with the main slot, reducing allocation overhead
and increasing cache density a bit.

Author: Andres Freund
Discussion: https://postgr.es/m/20171206093717.vqdxe5icqttpxs3p@alap3.anarazel.de

1 files changed, 12 insertions, 13 deletions

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 2a8ecbd830d..93c03cfb071 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -2367,8 +2367,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		mtstate->ps.plan->targetlist = (List *) linitial(node->returningLists);
 
 		/* Set up a slot for the output of the RETURNING projection(s) */
-		ExecInitResultTupleSlot(estate, &mtstate->ps);
-		ExecAssignResultTypeFromTL(&mtstate->ps);
+		ExecInitResultTupleSlotTL(estate, &mtstate->ps);
 		slot = mtstate->ps.ps_ResultTupleSlot;
 
 		/* Need an econtext too */
@@ -2435,8 +2434,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		 * expects one (maybe should change that?).
 		 */
 		mtstate->ps.plan->targetlist = NIL;
-		ExecInitResultTupleSlot(estate, &mtstate->ps);
-		ExecAssignResultTypeFromTL(&mtstate->ps);
+		ExecInitResultTupleSlotTL(estate, &mtstate->ps);
 
 		mtstate->ps.ps_ExprContext = NULL;
 	}
@@ -2449,6 +2447,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	if (node->onConflictAction == ONCONFLICT_UPDATE)
 	{
 		ExprContext *econtext;
+		TupleDesc	relationDesc;
 		TupleDesc	tupDesc;
 
 		/* insert may only have one plan, inheritance is not expanded */
@@ -2459,26 +2458,26 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 			ExecAssignExprContext(estate, &mtstate->ps);
 
 		econtext = mtstate->ps.ps_ExprContext;
+		relationDesc = resultRelInfo->ri_RelationDesc->rd_att;
 
 		/* initialize slot for the existing tuple */
-		mtstate->mt_existing = ExecInitExtraTupleSlot(mtstate->ps.state);
-		ExecSetSlotDescriptor(mtstate->mt_existing,
-							  resultRelInfo->ri_RelationDesc->rd_att);
+		mtstate->mt_existing =
+			ExecInitExtraTupleSlot(mtstate->ps.state, relationDesc);
 
 		/* carried forward solely for the benefit of explain */
 		mtstate->mt_excludedtlist = node->exclRelTlist;
 
 		/* create target slot for UPDATE SET projection */
 		tupDesc = ExecTypeFromTL((List *) node->onConflictSet,
-								 resultRelInfo->ri_RelationDesc->rd_rel->relhasoids);
-		mtstate->mt_conflproj = ExecInitExtraTupleSlot(mtstate->ps.state);
-		ExecSetSlotDescriptor(mtstate->mt_conflproj, tupDesc);
+								 relationDesc->tdhasoid);
+		mtstate->mt_conflproj =
+			ExecInitExtraTupleSlot(mtstate->ps.state, tupDesc);
 
 		/* build UPDATE SET projection state */
 		resultRelInfo->ri_onConflictSetProj =
 			ExecBuildProjectionInfo(node->onConflictSet, econtext,
 									mtstate->mt_conflproj, &mtstate->ps,
-									resultRelInfo->ri_RelationDesc->rd_att);
+									relationDesc);
 
 		/* build DO UPDATE WHERE clause expression */
 		if (node->onConflictWhere)
@@ -2583,7 +2582,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 
 				j = ExecInitJunkFilter(subplan->targetlist,
 									   resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
-									   ExecInitExtraTupleSlot(estate));
+									   ExecInitExtraTupleSlot(estate, NULL));
 
 				if (operation == CMD_UPDATE || operation == CMD_DELETE)
 				{
@@ -2633,7 +2632,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	 * we keep it in the estate.
 	 */
 	if (estate->es_trig_tuple_slot == NULL)
-		estate->es_trig_tuple_slot = ExecInitExtraTupleSlot(estate);
+		estate->es_trig_tuple_slot = ExecInitExtraTupleSlot(estate, NULL);
 
 	/*
 	 * Lastly, if this is not the primary (canSetTag) ModifyTable node, add it