From 02a2dbe91d37e521fb0dbeebc79ee9edd051f950 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Fri, 20 Nov 2020 14:41:14 +0200 Subject: [PATCH] Skip allocating hash table in EXPLAIN-only mode. This is a backpatch of commit 2cccb627f1, backpatched due to popular demand. Backpatch to all supported versions. Author: Alexey Bashtanov Discussion: https://www.postgresql.org/message-id/36823f65-050d-ae24-aa4d-a37726998240%40imap.cc --- src/backend/executor/nodeAgg.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c index cced591d02c..9c88ce661dc 100644 --- a/src/backend/executor/nodeAgg.c +++ b/src/backend/executor/nodeAgg.c @@ -2664,7 +2664,10 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) if (node->aggstrategy == AGG_HASHED) { - build_hash_table(aggstate); + /* Skip massive memory allocation if we are just doing EXPLAIN */ + if (!(eflags & EXEC_FLAG_EXPLAIN_ONLY)) + build_hash_table(aggstate); + aggstate->table_filled = false; /* Compute the columns we actually need to hash on */ aggstate->hash_needed = find_hash_columns(aggstate);