Make pull_var_clause() handle GroupingFuncs exactly like Aggrefs.

This follows in the footsteps of commit 2591ee8ec by removing one more
ill-advised shortcut from planning of GroupingFuncs.  It's true that
we don't intend to execute the argument expression(s) at runtime, but
we still have to process any Vars appearing within them, or we risk
failure at setrefs.c time (or more fundamentally, in EXPLAIN trying
to print such an expression).  Vars in upper plan nodes have to have
referents in the next plan level, whether we ever execute 'em or not.

Per bug #17479 from Michael J. Sullivan.  Back-patch to all supported
branches.

Richard Guo

Discussion: https://postgr.es/m/17479-6260deceaf0ad304@postgresql.org

diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index b8d7d3ffadcf545ef395d860b268f5a17bcd3579..da16bf9fa462a4b5515ff1fbf86055c1833288d6 100644 (file)
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -517,7 +517,7 @@ locate_var_of_level_walker(Node *node,
  *   Vars within a PHV's expression are included in the result only
  *   when PVC_RECURSE_PLACEHOLDERS is specified.
  *
- *   GroupingFuncs are treated mostly like Aggrefs, and so do not need
+ *   GroupingFuncs are treated exactly like Aggrefs, and so do not need
  *   their own flag bits.
  *
  *   CurrentOfExpr nodes are ignored in all cases.
@@ -592,13 +592,7 @@ pull_var_clause_walker(Node *node, pull_var_clause_context *context)
        }
        else if (context->flags & PVC_RECURSE_AGGREGATES)
        {
-           /*
-            * We do NOT descend into the contained expression, even if the
-            * caller asked for it, because we never actually evaluate it -
-            * the result is driven entirely off the associated GROUP BY
-            * clause, so we never need to extract the actual Vars here.
-            */
-           return false;
+           /* fall through to recurse into the GroupingFunc's arguments */
        }
        else
            elog(ERROR, "GROUPING found where not expected");

diff --git a/src/test/regress/expected/groupingsets.out b/src/test/regress/expected/groupingsets.out
index 077506f58f51296fedcc149c8dbd475a4915dad2..d052f365c70260281042c7b7395997fc409e261c 100644 (file)
--- a/src/test/regress/expected/groupingsets.out
+++ b/src/test/regress/expected/groupingsets.out
@@ -466,6 +466,70 @@ where x = 1 and q1 = 123;
 ---+----+-----
 (0 rows)
 
+-- check handling of pulled-up SubPlan in GROUPING() argument (bug #17479)
+explain (verbose, costs off)
+select grouping(ss.x)
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+                   QUERY PLAN                   
+------------------------------------------------
+ GroupAggregate
+   Output: GROUPING((SubPlan 1)), ((SubPlan 2))
+   Group Key: ((SubPlan 2))
+   ->  Sort
+         Output: ((SubPlan 2)), i1.q1
+         Sort Key: ((SubPlan 2))
+         ->  Seq Scan on public.int8_tbl i1
+               Output: (SubPlan 2), i1.q1
+               SubPlan 2
+                 ->  Result
+                       Output: i1.q1
+(11 rows)
+
+select grouping(ss.x)
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+ grouping 
+----------
+        0
+        0
+(2 rows)
+
+explain (verbose, costs off)
+select (select grouping(ss.x))
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+                 QUERY PLAN                 
+--------------------------------------------
+ GroupAggregate
+   Output: (SubPlan 2), ((SubPlan 3))
+   Group Key: ((SubPlan 3))
+   ->  Sort
+         Output: ((SubPlan 3)), i1.q1
+         Sort Key: ((SubPlan 3))
+         ->  Seq Scan on public.int8_tbl i1
+               Output: (SubPlan 3), i1.q1
+               SubPlan 3
+                 ->  Result
+                       Output: i1.q1
+   SubPlan 2
+     ->  Result
+           Output: GROUPING((SubPlan 1))
+(14 rows)
+
+select (select grouping(ss.x))
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+ grouping 
+----------
+        0
+        0
+(2 rows)
+
 -- simple rescan tests
 select a, b, sum(v.x)
   from (values (1),(2)) v(x), gstest_data(v.x)

diff --git a/src/test/regress/sql/groupingsets.sql b/src/test/regress/sql/groupingsets.sql
index e56ac55acc5053693448c40dc12a05849fa7a63a..dd41687faa61c6a916d20c230978a24038067e12 100644 (file)
--- a/src/test/regress/sql/groupingsets.sql
+++ b/src/test/regress/sql/groupingsets.sql
@@ -188,6 +188,29 @@ select * from (
 ) ss
 where x = 1 and q1 = 123;
 
+-- check handling of pulled-up SubPlan in GROUPING() argument (bug #17479)
+explain (verbose, costs off)
+select grouping(ss.x)
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+
+select grouping(ss.x)
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+
+explain (verbose, costs off)
+select (select grouping(ss.x))
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+
+select (select grouping(ss.x))
+from int8_tbl i1
+cross join lateral (select (select i1.q1) as x) ss
+group by ss.x;
+
 -- simple rescan tests
 
 select a, b, sum(v.x)