Fix query jumbling with GROUP BY clauses

RangeTblEntry.groupexprs was marked with the node attribute
query_jumble_ignore, causing a list of GROUP BY expressions to be
ignored during the query jumbling.  For example, these two queries could
be grouped together within the same query ID:
SELECT count(*) FROM t GROUP BY a;
SELECT count(*) FROM t GROUP BY b;

However, as such queries use different GROUP BY clauses, they should be
split across multiple entries.

This fixes an oversight in 247dea89f7, that has introduced an RTE for
GROUP BY clauses.  Query IDs are documented as being stable across minor
releases, but as this is a regression new to v18 and that we are still
early in its support cycle, a backpatch is exceptionally done as this
has broken a behavior that exists since query jumbling is supported in
core, since its introduction in pg_stat_statements.

The tests of pg_stat_statements are expanded to cover this area, with
patterns involving GROUP BY and GROUPING clauses.

Author: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEy2W+tCqC7XuJ94r3ivWsM=onKJp94kRFx3hoARjBeFQ@mail.gmail.com
Backpatch-through: 18

contrib/pg_stat_statements/expected/select.out

@@ -459,6 +459,102 @@ SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%FETCH FIRST%';
      2
 (1 row)
 
+-- GROUP BY, HAVING, GROUPING
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+ count 
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+ count 
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+ count 
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+ count 
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPING SETS(a, ());
+ count 
+-------
+     1
+     1
+(2 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPING SETS(b, ());
+ count 
+-------
+     1
+     1
+(2 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVING a = 1;
+ count 
+-------
+     1
+(1 row)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVING a = 2;
+ count 
+-------
+(0 rows)
+
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b HAVING b = 1;
+ count 
+-------
+(0 rows)
+
+SELECT GROUPING(a) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a;
+ grouping 
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b;
+ grouping 
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a, b;
+ grouping 
+----------
+        0
+(1 row)
+
+SELECT GROUPING(b) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b, a;
+ grouping 
+----------
+        0
+(1 row)
+
+SELECT calls, query FROM pg_stat_statements WHERE query LIKE '%GROUP BY%' ORDER BY query COLLATE "C";
+ calls |                                           query                                           
+-------+-------------------------------------------------------------------------------------------
+     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 = $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 = $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) GROUP BY a
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP BY a, b
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP BY b
+     1 | SELECT GROUPING(b) FROM (VALUES ($1::INT, $2::INT)) AS t(a, b) GROUP 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 
 -------
-     2
+     6
 (1 row)
 
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;

contrib/pg_stat_statements/sql/select.sql

@@ -158,6 +158,22 @@ FETCH FIRST 2 ROW ONLY;
 
 SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%FETCH FIRST%';
 
+-- 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 GROUPING SETS(a, ());
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY GROUPING SETS(b, ());
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVING a = 1;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY a HAVING a = 2;
+SELECT COUNT(*) FROM (VALUES (1::INT, 2::INT)) AS t(a, b) GROUP BY b HAVING b = 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)

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;
 
 	/*
 	 * Fields valid in all RTEs: