From f370dbc5736923728068db94bdd4266888f76e13 Mon Sep 17 00:00:00 2001
From: Tender Wang <tndrwang@gmail.com>
Date: Mon, 14 Apr 2025 13:53:15 +0800
Subject: [PATCH] Adjust the place of list_copy() in
 estimate_multivariate_bucketsize.

If we have a single hashclause, list_copy(hashclauses) is unnecessary.
This adjustment can save the overhead of function calls and memory
copies.
---
 src/backend/utils/adt/selfuncs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index a96b1b9c0bc6..cabc25c4a46c 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -3799,18 +3799,18 @@ estimate_multivariate_bucketsize(PlannerInfo *root, RelOptInfo *inner,
 								 List *hashclauses,
 								 Selectivity *innerbucketsize)
 {
-	List	   *clauses = list_copy(hashclauses);
+	List	   *clauses = NIL;
 	List	   *otherclauses = NIL;
 	double		ndistinct = 1.0;
 
+	/*
+	 * Nothing to do for a single clause.  Could we employ univariate
+	 * extended stat here?
+	 */
 	if (list_length(hashclauses) <= 1)
-
-		/*
-		 * Nothing to do for a single clause.  Could we employ univariate
-		 * extended stat here?
-		 */
 		return hashclauses;
 
+	clauses = list_copy(hashclauses);
 	while (clauses != NIL)
 	{
 		ListCell   *lc;