Fix server crash under rebuilding of RTEs and RelOptInfos

The GROUPING SETS statement with multiple canonical rollups working on
randomly distributed partitioned table causes rebuilding of
root->simple_rte_array and root->simple_rel_array on planning stage by
PostgreSQL optimizer. The rebuilding process initializes both RTEs and
RelOptInfos item by item and doesn't take into account that the
build_simple_rel() routine is recursive for inherited relations and
requires a full list of already initialized child RTEs inside
root->simple_rte_array. As a result, the call of build_simple_rel() fails
on the access to child RTEs.

The current fix segregates loops of building root->simple_rte_array and
root->simple_rel_array trying to leave a whole semantics unchanged.

src/backend/optimizer/plan/plangroupext.c

@@ -2241,7 +2241,6 @@ rebuild_append_simple_rel_and_rte(PlannerInfo *root,
 	int			i;
 	int			array_size;
 	ListCell	*l1, *l2, *l3;
-	RelOptInfo	*rel;
 
 	if (root->simple_rel_array)
 		pfree(root->simple_rel_array);
@@ -2259,23 +2258,56 @@ rebuild_append_simple_rel_and_rte(PlannerInfo *root,
 	Assert(list_length(rtable) == list_length(subplans));
 	Assert(list_length(subplans) == list_length(subroots));
 
+	/*
+	 * Build RTE array before initialization of RelOptInfos because
+	 * build_simple_rel() routine called from inside the next loop is recursive
+	 * for inherited relations that require a full list of already initialized
+	 * child RTEs.
+	 */
 	i = 0;
-	forthree(l1, rtable, l2, subroots, l3, subplans)
+	foreach(l1, rtable)
+	{
+		RangeTblEntry	*rte = (RangeTblEntry *)lfirst(l1);
+
+		/* the first array entry is not indexed */
+		i++;
+
+		/* skip empty RTE and join */
+		if (rte == NULL || rte->rtekind == RTE_JOIN)
+			continue;
+
+		root->simple_rte_array[i] = rte;
+	}
+
+	i = 0;
+	forboth(l2, subroots, l3, subplans)
 	{
 		SubqueryScan	*splan;
 		PlannerInfo		*sroot;
 		RangeTblEntry	*rte;
+		RelOptInfo		*rel;
 
-		/* skip the first one */
+		/* the first array entry is not indexed */
 		i++;
 
-		rte = (RangeTblEntry *)lfirst(l1);
-		if (rte == NULL || rte->rtekind == RTE_JOIN)
+		rte = root->simple_rte_array[i];
+		rel = root->simple_rel_array[i];
+
+		/* skip empty RTE and already initialized RelOptInfo */
+		if (rte == NULL || rel != NULL)
 			continue;
 
-		root->simple_rte_array[i] = rte; 
 		if (rte->rtekind == RTE_VOID)
+		{
 			rel = makeNode(RelOptInfo);
+
+			/*
+			 * XXX: save empty RelOptInfo that corresponds to deleted RTE
+			 * (former pulled up subquery) in common array. This can be
+			 * incorrect decision.
+			 */
+			root->simple_rel_array[i] = rel;
+		}
 		else
 			rel = build_simple_rel(root, i, RELOPT_BASEREL);
 

src/test/regress/expected/aggregate_with_groupingsets.out

@@ -36,3 +36,55 @@ FROM
       | Bed   |     300
 (6 rows)
 
+--
+-- Case for partitioned table
+--
+--
+-- Create new table bar
+--
+CREATE TABLE pfoo(type INTEGER, prod VARCHAR, quantity NUMERIC)
+DISTRIBUTED RANDOMLY
+PARTITION BY RANGE (quantity) (
+	partition "1" start (0) end (100),
+	partition "2" start (100) end (200),
+	partition "3" start (200) end (300),
+	partition "4" start (300) end (400)
+);
+NOTICE:  CREATE TABLE will create partition "pfoo_1_prt_1" for table "pfoo"
+NOTICE:  CREATE TABLE will create partition "pfoo_1_prt_2" for table "pfoo"
+NOTICE:  CREATE TABLE will create partition "pfoo_1_prt_3" for table "pfoo"
+NOTICE:  CREATE TABLE will create partition "pfoo_1_prt_4" for table "pfoo"
+--
+-- Insert some values
+--
+INSERT INTO pfoo VALUES
+  (1, 'Table', 100),
+  (2, 'Chair', 250),
+  (3, 'Bed', 300);
+--
+-- Turn off GPORCA
+--
+set optimizer to off;
+--
+-- Select query with grouping sets
+--
+SELECT type, prod, sum(quantity) s_quant
+FROM (
+	SELECT * FROM pfoo
+) AS t
+GROUP BY GROUPING SETS((type), (prod))
+ORDER BY type, s_quant;
+ type | prod  | s_quant 
+------+-------+---------
+    1 |       |     100
+    2 |       |     250
+    3 |       |     300
+      | Table |     100
+      | Chair |     250
+      | Bed   |     300
+(6 rows)
+
+--
+-- Reset settings
+--
+reset optimizer;

src/test/regress/greenplum_schedule

@@ -155,8 +155,8 @@ test: catalog
 test: bfv_catalog bfv_index bfv_olap bfv_aggregate bfv_partition bfv_partition_plans DML_over_joins gporca bfv_statistic
 # NOTE: gporca_faults uses gp_fault_injector - so do not add to a parallel group
 test: gporca_faults
- 
-test: aggregate_with_groupingsets 
+
+test: aggregate_with_groupingsets
 
 test: nested_case_null sort bb_mpph
 test: bb_memory_quota memconsumption

src/test/regress/sql/aggregate_with_groupingsets.sql

@@ -26,3 +26,48 @@ FROM
   FROM foo F1
   LIMIT 3
 ) F2 GROUP BY GROUPING SETS((type, prod), (prod)) ORDER BY type, s_quant;
+
+
+--
+-- Case for partitioned table
+--
+
+--
+-- Create new table bar
+--
+CREATE TABLE pfoo(type INTEGER, prod VARCHAR, quantity NUMERIC)
+DISTRIBUTED RANDOMLY
+PARTITION BY RANGE (quantity) (
+	partition "1" start (0) end (100),
+	partition "2" start (100) end (200),
+	partition "3" start (200) end (300),
+	partition "4" start (300) end (400)
+);
+
+--
+-- Insert some values
+--
+INSERT INTO pfoo VALUES
+  (1, 'Table', 100),
+  (2, 'Chair', 250),
+  (3, 'Bed', 300);
+
+--
+-- Turn off GPORCA
+--
+set optimizer to off;
+
+--
+-- Select query with grouping sets
+--
+SELECT type, prod, sum(quantity) s_quant
+FROM (
+	SELECT * FROM pfoo
+) AS t
+GROUP BY GROUPING SETS((type), (prod))
+ORDER BY type, s_quant;
+
+--
+-- Reset settings
+--
+reset optimizer;