From 3df0846dfe41955353287b4b33caf43e1dd2e399 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 8 Sep 2025 16:41:03 -0400 Subject: [PATCH v04 2/2] Eliminate duplicative hashtempcxt in nodeSubplan.c. Instead of building a separate memory context that's used just for running hash functions, make the hash functions run in the per-tuple context of the node's innerecontext. This saves a little space at runtime, and it avoids needing to reset two contexts instead of one inside buildSubPlanHash's main loop. Per discussion of bug #19040, although this is not directly a fix for that. Author: Tom Lane Discussion: https://postgr.es/m/19040-c9b6073ef814f48c@postgresql.org --- src/backend/executor/nodeSubplan.c | 19 +++++-------------- src/include/nodes/execnodes.h | 1 - 2 files changed, 5 insertions(+), 15 deletions(-) diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c index 8e55dcc159b..53fb56f7388 100644 --- a/src/backend/executor/nodeSubplan.c +++ b/src/backend/executor/nodeSubplan.c @@ -191,8 +191,8 @@ ExecHashSubPlan(SubPlanState *node, */ ExecClearTuple(slot); - /* Also must reset the hashtempcxt after each hashtable lookup. */ - MemoryContextReset(node->hashtempcxt); + /* Also must reset the innerecontext after each hashtable lookup. */ + ResetExprContext(node->innerecontext); return BoolGetDatum(result); } @@ -529,7 +529,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext) 0, node->planstate->state->es_query_cxt, node->hashtablecxt, - node->hashtempcxt, + innerecontext->ecxt_per_tuple_memory, false); if (!subplan->unknownEqFalse) @@ -558,7 +558,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext) 0, node->planstate->state->es_query_cxt, node->hashtablecxt, - node->hashtempcxt, + innerecontext->ecxt_per_tuple_memory, false); } else @@ -620,12 +620,9 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext) /* * Reset innerecontext after each inner tuple to free any memory used - * during ExecProject. + * during ExecProject and hashtable lookup. */ ResetExprContext(innerecontext); - - /* Also must reset the hashtempcxt after each hashtable lookup. */ - MemoryContextReset(node->hashtempcxt); } /* @@ -842,7 +839,6 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent) sstate->hashtable = NULL; sstate->hashnulls = NULL; sstate->hashtablecxt = NULL; - sstate->hashtempcxt = NULL; sstate->innerecontext = NULL; sstate->keyColIdx = NULL; sstate->tab_eq_funcoids = NULL; @@ -898,11 +894,6 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent) AllocSetContextCreate(CurrentMemoryContext, "Subplan HashTable Context", ALLOCSET_DEFAULT_SIZES); - /* and a small one for the hash tables to use as temp storage */ - sstate->hashtempcxt = - AllocSetContextCreate(CurrentMemoryContext, - "Subplan HashTable Temp Context", - ALLOCSET_SMALL_SIZES); /* and a short-lived exprcontext for function evaluation */ sstate->innerecontext = CreateExprContext(estate); diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index de782014b2d..71857feae48 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1020,7 +1020,6 @@ typedef struct SubPlanState bool havehashrows; /* true if hashtable is not empty */ bool havenullrows; /* true if hashnulls is not empty */ MemoryContext hashtablecxt; /* memory context containing hash tables */ - MemoryContext hashtempcxt; /* temp memory context for hash tables */ ExprContext *innerecontext; /* econtext for computing inner tuples */ int numCols; /* number of columns being hashed */ /* each of the remaining fields is an array of length numCols: */ -- 2.43.7