postgres.git / summary / log / commit / refs

commit    ded7db4c1dddcead3184b17619ddc5c203db42fe
Author:   Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:     Fri Nov 20 12:41:14 2020 +0000
First released in: 14.0, 9.5.25, 9.6.21, 10.16, 11.11, 12.6, 13.2

    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 a9e1fbb842e..41bfbb75d6f 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -2254,7 +2254,10 @@ 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);


[parent: 2bb8c0f1d94d]