0001-Add-partial-path-only-when-rel-s-consider_parallel-i.patch

From 708026f34f6a5d087660930f9cb05aa3e08c130b Mon Sep 17 00:00:00 2001
From: Jeevan Chalke <jeevan.chalke@enterprisedb.com>
Date: Wed, 11 Apr 2018 14:08:13 +0530
Subject: [PATCH] Add partial path only when rel's consider_parallel is true.

Otherwise, it will result in an assertion failure later in the
create_gather_path().
---
 src/backend/optimizer/path/allpaths.c         | 41 +++++++++++++++------------
 src/backend/optimizer/prep/prepunion.c        |  3 +-
 src/backend/optimizer/util/pathnode.c         |  6 ++++
 src/test/regress/expected/select_parallel.out | 19 +++++++++++++
 src/test/regress/sql/select_parallel.sql      |  6 ++++
 5 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 3ba3f87..c3d0634 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -2242,26 +2242,31 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
 										  pathkeys, required_outer));
 	}
 
-	/* If consider_parallel is false, there should be no partial paths. */
-	Assert(sub_final_rel->consider_parallel ||
-		   sub_final_rel->partial_pathlist == NIL);
-
-	/* Same for partial paths. */
-	foreach(lc, sub_final_rel->partial_pathlist)
+	/* If outer rel allows parallelism, do same for partial paths. */
+	if (rel->consider_parallel && bms_is_empty(required_outer))
 	{
-		Path	   *subpath = (Path *) lfirst(lc);
-		List	   *pathkeys;
-
-		/* Convert subpath's pathkeys to outer representation */
-		pathkeys = convert_subquery_pathkeys(root,
-											 rel,
-											 subpath->pathkeys,
-											 make_tlist_from_pathtarget(subpath->pathtarget));
+		/* If consider_parallel is false, there should be no partial paths. */
+		Assert(sub_final_rel->consider_parallel ||
+			   sub_final_rel->partial_pathlist == NIL);
 
-		/* Generate outer path using this subpath */
-		add_partial_path(rel, (Path *)
-						 create_subqueryscan_path(root, rel, subpath,
-												  pathkeys, required_outer));
+		/* Same for partial paths. */
+		foreach(lc, sub_final_rel->partial_pathlist)
+		{
+			Path	   *subpath = (Path *) lfirst(lc);
+			List	   *pathkeys;
+
+			/* Convert subpath's pathkeys to outer representation */
+			pathkeys = convert_subquery_pathkeys(root,
+												 rel,
+												 subpath->pathkeys,
+												 make_tlist_from_pathtarget(subpath->pathtarget));
+
+			/* Generate outer path using this subpath */
+			add_partial_path(rel, (Path *)
+							 create_subqueryscan_path(root, rel, subpath,
+													  pathkeys,
+													  required_outer));
+		}
 	}
 }
 
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 8d86e98..61d0770 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -330,7 +330,8 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
 		 * to build a partial path for this relation.  But there's no point in
 		 * considering any path but the cheapest.
 		 */
-		if (final_rel->partial_pathlist != NIL)
+		if (rel->consider_parallel && bms_is_empty(rel->lateral_relids) &&
+			final_rel->partial_pathlist != NIL)
 		{
 			Path	   *partial_subpath;
 			Path	   *partial_path;
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index bd9442c..561466c 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -770,6 +770,12 @@ add_partial_path(RelOptInfo *parent_rel, Path *new_path)
 	/* Check for query cancel. */
 	CHECK_FOR_INTERRUPTS();
 
+	/* Path to be added must be parallel safe. */
+	Assert(new_path->parallel_safe);
+
+	/* Relation should be OK for parallelism, too. */
+	Assert(parent_rel->consider_parallel);
+
 	/*
 	 * As in add_path, throw out any paths which are dominated by the new
 	 * path, but throw out the new path if some existing path dominates it.
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index fb209de..a07cd50 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -955,4 +955,23 @@ ORDER BY 1, 2, 3;
 ------------------------------+---------------------------+-------------+--------------
 (0 rows)
 
+-- test interation between subquery and partial_paths
+SET LOCAL min_parallel_table_scan_size TO 0;
+CREATE VIEW tenk1_vw_sec WITH (security_barrier) AS SELECT * FROM tenk1;
+EXPLAIN (COSTS OFF)
+SELECT 1 FROM tenk1_vw_sec WHERE EXISTS (SELECT 1 WHERE unique1 = 0);
+                            QUERY PLAN                             
+-------------------------------------------------------------------
+ Subquery Scan on tenk1_vw_sec
+   Filter: (alternatives: SubPlan 1 or hashed SubPlan 2)
+   ->  Gather
+         Workers Planned: 4
+         ->  Parallel Index Only Scan using tenk1_unique1 on tenk1
+   SubPlan 1
+     ->  Result
+           One-Time Filter: (tenk1_vw_sec.unique1 = 0)
+   SubPlan 2
+     ->  Result
+(10 rows)
+
 rollback;
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index ac26d68..7db75b0 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -383,4 +383,10 @@ ORDER BY 1;
 SELECT * FROM information_schema.foreign_data_wrapper_options
 ORDER BY 1, 2, 3;
 
+-- test interation between subquery and partial_paths
+SET LOCAL min_parallel_table_scan_size TO 0;
+CREATE VIEW tenk1_vw_sec WITH (security_barrier) AS SELECT * FROM tenk1;
+EXPLAIN (COSTS OFF)
+SELECT 1 FROM tenk1_vw_sec WHERE EXISTS (SELECT 1 WHERE unique1 = 0);
+
 rollback;
-- 
1.8.3.1