Feedback-ID: i0fe9450f:Fastmail
Date: Tue, 13 Jan 2026 16:09:46 +0900
From: Michael Paquier <michael@paquier.xyz>
To: jian he <jian.universality@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Richard Guo <guofenglinux@gmail.com>
Subject: Re: JumbleQuery ma treat different GROUP BY expr as the same
Message-ID: <aWXvug98FbHvp22H@paquier.xyz>
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On Mon, Jan 12, 2026 at 04:20:44PM +0800, jian he wrote:
> While working on it, I guess I found another bug,  below JumbleQuery will=
 return
> the same result:
>=20
> SELECT FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;
> SELECT a FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;
> SELECT a, b FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;
>=20
> so I think TargetEntry.resjunk should not be marked as query_jumble_ignor=
e.

Not sure how to feel about this one, as a primary node.  3db72ebcbe20
has put a query_jumble_ignore to TargetEntry.resjunk which was simply
a consistent move with the pre-v15 branches because these columns have
always been ignored.  I have never heard complaints about that in the
field with PGSS, TBH.  The original choice comes from this thread,
back in 2012 when this was still integrated into PGSS:
https://www.postgresql.org/message-id/CAEYLb_WGeFCT7MfJ8FXf-CR6BSE6Lbn%2BO1=
VX3%2BOGrc4Bscn4%3DA%40mail.gmail.com

Anyway, let's not mix apples and oranges for now.  The GROUP BY issue
is a bug worth fixing on its own.  What you are pointing out with
resjunk is the original behavior we have been relying on.  If we
finish by changing it, this should not and cannot be backpatched.

I have expanded a bit the tests, with a couple of extra patterns,
giving the attached.  The behavior is the same as the pre-v17
branches.
--
Michael

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=46rom 0da22db67538f3ead39c4a4fcbe2afc3a513454f Mon Sep 17 00:00:00 2001
=46rom: jian he <jian.universality@gmail.com>
Date: Mon, 12 Jan 2026 16:17:37 +0800
Subject: [PATCH v2] Fix query jumbling computations with GROUP BY clauses

Discussion: https://postgr.es/m/CACJufxEy2W+tCqC7XuJ94r3ivWsM=3DonKJp94kRFx=
3hoARjBeFQ@mail.gmail.com
---
 src/include/nodes/parsenodes.h                |  2 +-
 .../pg_stat_statements/expected/select.out    | 98 ++++++++++++++++++-
 contrib/pg_stat_statements/sql/select.sql     | 16 +++
 3 files changed, 114 insertions(+), 2 deletions(-)

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index aac4bfc70d99..646d6ced763c 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1294,7 +1294,7 @@ typedef struct RangeTblEntry
 	 * Fields valid for a GROUP RTE (else NIL):
 	 */
 	/* list of grouping expressions */
-	List	   *groupexprs pg_node_attr(query_jumble_ignore);
+	List	   *groupexprs;
=20
 	/*
 	 * Fields valid in all RTEs:
diff --git a/contrib/pg_stat_statements/expected/select.out b/contrib/pg_st=
at_statements/expected/select.out
index 75c896f38851..a069119c7900 100644
--- a/contrib/pg_stat_statements/expected/select.out
+++ b/contrib/pg_stat_statements/expected/select.out
@@ -459,6 +459,102 @@ SELECT COUNT(*) FROM pg_stat_statements WHERE query L=
IKE '%FETCH FIRST%';
      2
 (1 row)
=20
+-- GROUP BY, HAVING, GROUPING
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+ count=20
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+ count=20
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+ count=20
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+ count=20
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPIN=
G SETS(a, ());
+ count=20
+-------
+     1
+     1
+(2 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPIN=
G SETS(b, ());
+ count=20
+-------
+     1
+     1
+(2 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVIN=
G a =3D 1;
+ count=20
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVIN=
G a =3D 2;
+ count=20
+-------
+(0 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b HAVIN=
G b =3D 1;
+ count=20
+-------
+(0 rows)
+
+SELECT GROUPING(a) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+ grouping=20
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+ grouping=20
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+ grouping=20
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+ grouping=20
+----------
+        0
+(1 row)
+
+SELECT calls, query FROM pg_stat_statements WHERE query LIKE '%GROUP BY%' =
ORDER BY query COLLATE "C";
+ calls |                                           query                  =
                        =20
+-------+------------------------------------------------------------------=
-------------------------
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY GROUPING SETS(a, ())
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY GROUPING SETS(b, ())
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY a
+     2 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY a HAVING a =3D $3
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY a, b
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY b
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY b HAVING b =3D $3
+     1 | SELECT COUNT(*) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP=
 BY b, a
+     1 | SELECT GROUPING(a) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GR=
OUP BY a
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GR=
OUP BY a, b
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GR=
OUP BY b
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GR=
OUP BY b, a
+(12 rows)
+
 -- GROUP BY [DISTINCT]
 SELECT a, b, c
 FROM (VALUES (1, 2, 3), (4, NULL, 6), (7, 8, 9)) AS t (a, b, c)
@@ -548,7 +644,7 @@ SELECT (
 SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%SELECT GROUPING=
%';
  count=20
 -------
-     2
+     6
 (1 row)
=20
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;
diff --git a/contrib/pg_stat_statements/sql/select.sql b/contrib/pg_stat_st=
atements/sql/select.sql
index 11662cde08c9..a10d618c034e 100644
--- a/contrib/pg_stat_statements/sql/select.sql
+++ b/contrib/pg_stat_statements/sql/select.sql
@@ -158,6 +158,22 @@ FETCH FIRST 2 ROW ONLY;
=20
 SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%FETCH FIRST%';
=20
+-- GROUP BY, HAVING, GROUPING
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPIN=
G SETS(a, ());
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPIN=
G SETS(b, ());
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVIN=
G a =3D 1;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVIN=
G a =3D 2;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b HAVIN=
G b =3D 1;
+SELECT GROUPING(a) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+SELECT calls, query FROM pg_stat_statements WHERE query LIKE '%GROUP BY%' =
ORDER BY query COLLATE "C";
+
 -- GROUP BY [DISTINCT]
 SELECT a, b, c
 FROM (VALUES (1, 2, 3), (4, NULL, 6), (7, 8, 9)) AS t (a, b, c)
--=20
2.51.0


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