unify handling of outer parameters for joins

src/backend/executor/nodeHashjoin.c

@@ -1190,6 +1190,10 @@ ExecReScanHashJoin(HashJoinState *node)
 	 * if it's a single-batch join, and there is no parameter change for the
 	 * inner subnode, then we can just re-use the existing hash table without
 	 * rebuilding it.
+	 *
+	 * GPDB: hybrid hash join was modified to spill out scanned batches
+	 * (including 0th batch) to disk to provide rescannability if it was
+	 * requested. See the SpillCurrentBatch comment for details.
 	 */
 	if (node->hj_HashTable != NULL)
 	{

src/backend/optimizer/util/pathnode.c

@@ -59,6 +59,8 @@ static CdbVisitOpt pathnode_walk_list(List *pathlist,
 static CdbVisitOpt pathnode_walk_kids(Path *path,
 				   CdbVisitOpt (*walker)(Path *path, void *context),
 				   void *context);
+static Path* ensure_outer_rescannable(PlannerInfo *root, Path *outer_path);
+static Path* ensure_inner_rescannable(PlannerInfo *root, Path *outer_path, Path *inner_path);
 
 /*
  * pathnode_walk_node
@@ -224,6 +226,53 @@ pathnode_walk_kids(Path            *path,
 }	                            /* pathnode_walk_kids */
 
 
+static Path*
+ensure_outer_rescannable(PlannerInfo *root, Path *outer_path)
+{
+	if (!outer_path->rescannable)
+	{
+		MaterialPath *matouter = create_material_path(root, outer_path->parent, outer_path);
+
+		matouter->cdb_shield_child_from_rescans = true;
+
+		outer_path = (Path *) matouter;
+	}
+
+	return outer_path;
+}
+
+static Path*
+ensure_inner_rescannable(PlannerInfo *root, Path *outer_path, Path *inner_path)
+{
+	if (!inner_path->rescannable)
+	{
+		/*
+		 * NLs potentially rescan the inner; if our inner path
+		 * isn't rescannable we have to add a materialize node
+		 */
+		MaterialPath *matinner = create_material_path(root, inner_path->parent, inner_path);
+
+		matinner->cdb_shield_child_from_rescans = true;
+
+		/*
+		 * If we have motion on the outer, to avoid a deadlock; we
+		 * need to set cdb_strict. In order for materialize to
+		 * fully fetch the underlying (required to avoid our
+		 * deadlock hazard) we must set cdb_strict!
+		 */
+		if (inner_path->motionHazard && outer_path->motionHazard)
+		{
+			matinner->cdb_strict = true;
+			matinner->path.motionHazard = false;
+		}
+
+		inner_path = (Path *) matinner;
+	}
+
+	return inner_path;
+}
+
+
 /*****************************************************************************
  *		MISC. PATH UTILITIES
  *****************************************************************************/
@@ -3218,47 +3267,18 @@ create_nestloop_path(PlannerInfo *root,
 
 	/*
 	 * If this join path is parameterized by a parameter above this path, then
-	 * this path needs to be rescannable. A NestLoop is rescannable, when both
+	 * this path needs to be rescannable. Joins are rescannable, when both
 	 * outer and inner paths rescannable, so make them both rescannable.
 	 */
-	if (!outer_path->rescannable && !bms_is_empty(required_outer))
-	{
-		MaterialPath *matouter = create_material_path(root, outer_path->parent, outer_path);
-
-		matouter->cdb_shield_child_from_rescans = true;
-
-		outer_path = (Path *) matouter;
-	}
+	if (!bms_is_empty(required_outer))
+		outer_path = ensure_outer_rescannable(root, outer_path);
 
 	/*
 	 * If outer has at most one row, NJ will make at most one pass over inner.
 	 * Else materialize inner rel after motion so NJ can loop over results.
 	 */
-	if (!inner_path->rescannable &&
-		(!outer_path->parent->onerow || !bms_is_empty(required_outer)))
-	{
-		/*
-		 * NLs potentially rescan the inner; if our inner path
-		 * isn't rescannable we have to add a materialize node
-		 */
-		MaterialPath *matinner = create_material_path(root, inner_path->parent, inner_path);
-
-		matinner->cdb_shield_child_from_rescans = true;
-
-		/*
-		 * If we have motion on the outer, to avoid a deadlock; we
-		 * need to set cdb_strict. In order for materialize to
-		 * fully fetch the underlying (required to avoid our
-		 * deadlock hazard) we must set cdb_strict!
-		 */
-		if (inner_path->motionHazard && outer_path->motionHazard)
-		{
-			matinner->cdb_strict = true;
-			matinner->path.motionHazard = false;
-		}
-
-		inner_path = (Path *) matinner;
-	}
+	if (!outer_path->parent->onerow || !bms_is_empty(required_outer))
+		inner_path = ensure_inner_rescannable(root, outer_path, inner_path);
 
 	/*
 	 * If the inner path is parameterized by the outer, we must drop any
@@ -3456,6 +3476,17 @@ create_mergejoin_path(PlannerInfo *root,
 		inner_path->pathkeys)
 		innersortkeys = NIL;
 
+	/*
+	 * If this join path is parameterized by a parameter above this path, then
+	 * this path needs to be rescannable. Joins are rescannable, when both
+	 * outer and inner paths rescannable, so make them both rescannable.
+	 */
+	if (!bms_is_empty(required_outer))
+	{
+		outer_path = ensure_outer_rescannable(root, outer_path);
+		inner_path = ensure_inner_rescannable(root, outer_path, inner_path);
+	}
+
 	pathnode->jpath.path.pathtype = T_MergeJoin;
 	pathnode->jpath.path.parent = joinrel;
 	pathnode->jpath.path.param_info =
@@ -3573,6 +3604,17 @@ create_hashjoin_path(PlannerInfo *root,
 			return NULL;
 	}
 
+	/*
+	 * If this join path is parameterized by a parameter above this path, then
+	 * this path needs to be rescannable. Joins are rescannable, when both
+	 * outer and inner paths rescannable, so make them both rescannable.
+	 *
+	 * Hash Join inner side was customized in the GPDB to be always rescannable
+	 * (see the SpillCurrentBatch comment for details)
+	 */
+	if (!bms_is_empty(required_outer))
+		outer_path = ensure_outer_rescannable(root, outer_path);
+
 	pathnode = makeNode(HashPath);
 
 	pathnode->jpath.path.pathtype = T_HashJoin;

src/test/regress/expected/gporca.out

@@ -12595,8 +12595,9 @@ where out.b in (select coalesce(tcorr2_d.c, 99)
    ->  Materialize  (cost=1.07..2.16 rows=2 width=8)
          ->  Hash Left Join  (cost=1.07..2.14 rows=4 width=8)
                Hash Cond: (tcorr1.a = tcorr2.a)
-               ->  Gather Motion 3:1  (slice2; segments: 3)  (cost=0.00..1.03 rows=1 width=4)
-                     ->  Seq Scan on tcorr1  (cost=0.00..1.01 rows=1 width=4)
+               ->  Materialize  (cost=0.00..1.03 rows=1 width=4)
+                     ->  Gather Motion 3:1  (slice2; segments: 3)  (cost=0.00..1.03 rows=1 width=4)
+                           ->  Seq Scan on tcorr1  (cost=0.00..1.01 rows=1 width=4)
                ->  Hash  (cost=1.06..1.06 rows=1 width=12)
                      ->  HashAggregate  (cost=1.04..1.05 rows=1 width=12)
                            Group Key: tcorr2.a
@@ -12606,7 +12607,7 @@ where out.b in (select coalesce(tcorr2_d.c, 99)
                                        ->  Gather Motion 3:1  (slice3; segments: 3)  (cost=0.00..1.03 rows=1 width=8)
                                              ->  Seq Scan on tcorr2  (cost=0.00..1.01 rows=1 width=8)
  Optimizer: Postgres query optimizer
-(18 rows)
+(19 rows)
 
 -- expect 1 row
 select *
@@ -12711,8 +12712,9 @@ where out.b in (select coalesce(tcorr2_d.c, 99)
    ->  Materialize  (cost=1.07..2.16 rows=2 width=8)
          ->  Hash Left Join  (cost=1.07..2.14 rows=4 width=8)
                Hash Cond: (tcorr1.a = tcorr2.a)
-               ->  Gather Motion 3:1  (slice2; segments: 3)  (cost=0.00..1.03 rows=1 width=4)
-                     ->  Seq Scan on tcorr1  (cost=0.00..1.01 rows=1 width=4)
+               ->  Materialize  (cost=0.00..1.03 rows=1 width=4)
+                     ->  Gather Motion 3:1  (slice2; segments: 3)  (cost=0.00..1.03 rows=1 width=4)
+                           ->  Seq Scan on tcorr1  (cost=0.00..1.01 rows=1 width=4)
                ->  Hash  (cost=1.06..1.06 rows=1 width=12)
                      ->  HashAggregate  (cost=1.04..1.05 rows=1 width=12)
                            Group Key: tcorr2.a
@@ -12722,7 +12724,7 @@ where out.b in (select coalesce(tcorr2_d.c, 99)
                                        ->  Gather Motion 3:1  (slice3; segments: 3)  (cost=0.00..1.03 rows=1 width=8)
                                              ->  Seq Scan on tcorr2  (cost=0.00..1.01 rows=1 width=8)
  Optimizer: Postgres query optimizer
-(18 rows)
+(19 rows)
 
 -- expect 1 row
 select *

src/test/regress/expected/join_gp.out

@@ -5,6 +5,10 @@
 -- start_matchignore
 -- m/ERROR:  workfile compresssion is not supported by this build/
 -- end_matchignore
+-- start_matchsubs
+-- m/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/
+-- s/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/ERROR:  could not devise a query plan for the given query (pathnode.c:XX)/
+-- end_matchsubs
 --
 -- test numeric hash join
 --

src/test/regress/expected/join_gp_optimizer.out

@@ -5,6 +5,10 @@
 -- start_matchignore
 -- m/ERROR:  workfile compresssion is not supported by this build/
 -- end_matchignore
+-- start_matchsubs
+-- m/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/
+-- s/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/ERROR:  could not devise a query plan for the given query (pathnode.c:XX)/
+-- end_matchsubs
 --
 -- test numeric hash join
 --

src/test/regress/sql/join_gp.sql

@@ -6,6 +6,10 @@
 -- start_matchignore
 -- m/ERROR:  workfile compresssion is not supported by this build/
 -- end_matchignore
+-- start_matchsubs
+-- m/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/
+-- s/ERROR:  could not devise a query plan for the given query \(pathnode.c:\d+\)/ERROR:  could not devise a query plan for the given query (pathnode.c:XX)/
+-- end_matchsubs
 
 --
 -- test numeric hash join