postgres_fdw: wrong results with self join + enable_nestloop off

From 32c854736b90aacad38715ab6c02b73140c8c429 Mon Sep 17 00:00:00 2001
From: Richard Guo <guofenglinux@gmail.com>
Date: Tue, 25 Apr 2023 16:10:42 +0800
Subject: [PATCH v1] Fix how we handle pseudoconstant clauses for scans of
 foreign joins

When creating a scan plan, we need to extract all the pseudoconstant clauses
which are supposed to be used as one-time quals in a gating Result node.
Normally it suffices to check against baserestrictinfo of the parent relation
of 'best_path', as well as the join clauses available from the outer relations
if this is a parameterized scan.  But for scans of foreign joins, we do not
have any restriction clauses in these places, and that leads to gating clauses
being lost in this case.

To fix, store the restriction clauses for foreign joins in ForeignPath and
check against them for gating clauses.
---
 .../postgres_fdw/expected/postgres_fdw.out    | 21 +++++++++++++++++++
 contrib/postgres_fdw/postgres_fdw.c           | 13 +++++++-----
 contrib/postgres_fdw/sql/postgres_fdw.sql     |  6 ++++++
 src/backend/optimizer/plan/createplan.c       |  9 +++++++-
 src/backend/optimizer/util/pathnode.c         |  4 ++++
 src/include/nodes/pathnodes.h                 |  5 +++++
 src/include/optimizer/pathnode.h              |  1 +
 7 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index fd5752bd5b..c8b072c255 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -893,6 +893,27 @@ SELECT * FROM ft2 WHERE c1 = ANY (ARRAY(SELECT c1 FROM ft1 WHERE c1 < 5));
   4 |  4 | 00004 | Mon Jan 05 00:00:00 1970 PST | Mon Jan 05 00:00:00 1970 | 4  | 4          | foo
 (4 rows)
 
+-- bug due to sloppy handling of pseudoconstant clauses for foreign joins
+EXPLAIN (VERBOSE, COSTS OFF)
+  SELECT * FROM ft2 a, ft2 b
+  WHERE b.c1 = a.c1 AND now() < '25-April-2023'::timestamp;
+                                                                                                          QUERY PLAN                                                                                                          
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Result
+   Output: a.c1, a.c2, a.c3, a.c4, a.c5, a.c6, a.c7, a.c8, b.c1, b.c2, b.c3, b.c4, b.c5, b.c6, b.c7, b.c8
+   One-Time Filter: (now() < 'Tue Apr 25 00:00:00 2023'::timestamp without time zone)
+   ->  Foreign Scan
+         Output: a.c1, a.c2, a.c3, a.c4, a.c5, a.c6, a.c7, a.c8, b.c1, b.c2, b.c3, b.c4, b.c5, b.c6, b.c7, b.c8
+         Relations: (public.ft2 a) INNER JOIN (public.ft2 b)
+         Remote SQL: SELECT r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8, r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8 FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1"))))
+(7 rows)
+
+SELECT * FROM ft2 a, ft2 b
+WHERE b.c1 = a.c1 AND now() < '25-April-2023'::timestamp;
+ c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8 | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8 
+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----
+(0 rows)
+
 -- we should not push order by clause with volatile expressions or unsafe
 -- collations
 EXPLAIN (VERBOSE, COSTS OFF)
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 95dbe8b06c..2c79981289 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -524,7 +524,7 @@ static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
 											  RelOptInfo *rel);
 static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
 static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-											Path *epq_path);
+											Path *epq_path, List *joinrestrictinfo);
 static void add_foreign_grouping_paths(PlannerInfo *root,
 									   RelOptInfo *input_rel,
 									   RelOptInfo *grouped_rel,
@@ -1038,7 +1038,7 @@ postgresGetForeignPaths(PlannerInfo *root,
 	add_path(baserel, (Path *) path);
 
 	/* Add paths with pathkeys */
-	add_paths_with_pathkeys_for_rel(root, baserel, NULL);
+	add_paths_with_pathkeys_for_rel(root, baserel, NULL, NULL);
 
 	/*
 	 * If we're not using remote estimates, stop here.  We have no way to
@@ -5992,7 +5992,7 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
 
 static void
 add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-								Path *epq_path)
+								Path *epq_path, List *joinrestrictinfo)
 {
 	List	   *useful_pathkeys_list = NIL; /* List of all pathkeys */
 	ListCell   *lc;
@@ -6096,6 +6096,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											  total_cost,
 											  useful_pathkeys,
 											  rel->lateral_relids,
+											  joinrestrictinfo,
 											  sorted_epq_path,
 											  NIL));
 	}
@@ -6348,6 +6349,7 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
 										total_cost,
 										NIL,	/* no pathkeys */
 										joinrel->lateral_relids,
+										extra->restrictlist,
 										epq_path,
 										NIL);	/* no fdw_private */
 
@@ -6355,7 +6357,8 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
 	add_path(joinrel, (Path *) joinpath);
 
 	/* Consider pathkeys for the join relation */
-	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path);
+	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path,
+									extra->restrictlist);
 
 	/* XXX Consider parameterized paths for the join relation */
 }
@@ -6981,7 +6984,7 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 													   path->total_cost,
 													   path->pathkeys,
 													   NULL,	/* no extra plan */
-													   NULL);	/* no fdw_private */
+													   NIL);	/* no fdw_private */
 
 				/* and add it to the final_rel */
 				add_path(final_rel, (Path *) final_path);
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index c05046f867..246f4c15d8 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -355,6 +355,12 @@ WHERE a.c2 = 6 AND b.c1 = a.c1 AND a.c8 = 'foo' AND b.c7 = upper(a.c7);
 -- bug before 9.3.5 due to sloppy handling of remote-estimate parameters
 SELECT * FROM ft1 WHERE c1 = ANY (ARRAY(SELECT c1 FROM ft2 WHERE c1 < 5));
 SELECT * FROM ft2 WHERE c1 = ANY (ARRAY(SELECT c1 FROM ft1 WHERE c1 < 5));
+-- bug due to sloppy handling of pseudoconstant clauses for foreign joins
+EXPLAIN (VERBOSE, COSTS OFF)
+  SELECT * FROM ft2 a, ft2 b
+  WHERE b.c1 = a.c1 AND now() < '25-April-2023'::timestamp;
+SELECT * FROM ft2 a, ft2 b
+WHERE b.c1 = a.c1 AND now() < '25-April-2023'::timestamp;
 -- we should not push order by clause with volatile expressions or unsafe
 -- collations
 EXPLAIN (VERBOSE, COSTS OFF)
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 910ffbf1e1..7e20e89813 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -599,8 +599,15 @@ create_scan_plan(PlannerInfo *root, Path *best_path, int flags)
 	 * Detect whether we have any pseudoconstant quals to deal with.  Then, if
 	 * we'll need a gating Result node, it will be able to project, so there
 	 * are no requirements on the child's tlist.
+	 *
+	 * Note that for scans of foreign joins, we do not have restriction clauses
+	 * stored in baserestrictinfo and we do not consider parameterization.
+	 * Instead we need to check against joinrestrictinfo stored in ForeignPath.
 	 */
-	gating_clauses = get_gating_quals(root, scan_clauses);
+	if (best_path->pathtype == T_ForeignScan && IS_JOIN_REL(rel))
+		gating_clauses = get_gating_quals(root, ((ForeignPath *) best_path)->joinrestrictinfo);
+	else
+		gating_clauses = get_gating_quals(root, scan_clauses);
 	if (gating_clauses)
 		flags = 0;
 
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 5f5596841c..92f18c6846 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2249,6 +2249,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.total_cost = total_cost;
 	pathnode->path.pathkeys = pathkeys;
 
+	pathnode->joinrestrictinfo = NIL;
 	pathnode->fdw_outerpath = fdw_outerpath;
 	pathnode->fdw_private = fdw_private;
 
@@ -2272,6 +2273,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 						 double rows, Cost startup_cost, Cost total_cost,
 						 List *pathkeys,
 						 Relids required_outer,
+						 List *joinrestrictinfo,
 						 Path *fdw_outerpath,
 						 List *fdw_private)
 {
@@ -2299,6 +2301,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.total_cost = total_cost;
 	pathnode->path.pathkeys = pathkeys;
 
+	pathnode->joinrestrictinfo = joinrestrictinfo;
 	pathnode->fdw_outerpath = fdw_outerpath;
 	pathnode->fdw_private = fdw_private;
 
@@ -2344,6 +2347,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.total_cost = total_cost;
 	pathnode->path.pathkeys = pathkeys;
 
+	pathnode->joinrestrictinfo = NIL;
 	pathnode->fdw_outerpath = fdw_outerpath;
 	pathnode->fdw_private = fdw_private;
 
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index cf28416da8..5adf35ac1d 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1828,6 +1828,10 @@ typedef struct SubqueryScanPath
  * ForeignPath represents a potential scan of a foreign table, foreign join
  * or foreign upper-relation.
  *
+ * In the case of foreign join, joinrestrictinfo stores the RestrictInfos to
+ * apply to this join.  It is needed because we need to extract gating clauses
+ * from it.
+ *
  * fdw_private stores FDW private data about the scan.  While fdw_private is
  * not actually touched by the core code during normal operations, it's
  * generally a good idea to use a representation that can be dumped by
@@ -1837,6 +1841,7 @@ typedef struct SubqueryScanPath
 typedef struct ForeignPath
 {
 	Path		path;
+	List	   *joinrestrictinfo;	/* RestrictInfos to apply to join */
 	Path	   *fdw_outerpath;
 	List	   *fdw_private;
 } ForeignPath;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 69be701b16..9f8f1b2798 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -134,6 +134,7 @@ extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 double rows, Cost startup_cost, Cost total_cost,
 											 List *pathkeys,
 											 Relids required_outer,
+											 List *joinrestrictinfo,
 											 Path *fdw_outerpath,
 											 List *fdw_private);
 extern ForeignPath *create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
-- 
2.31.0

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index c8c4614b54..98df6371c0 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,6 +2316,32 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
+                                  QUERY PLAN                                   
+-------------------------------------------------------------------------------
+ Limit
+   Output: t1.c1, t2.c1, t1.c3
+   ->  Sort
+         Output: t1.c1, t2.c1, t1.c3
+         Sort Key: t1.c3, t1.c1
+         ->  Result
+               Output: t1.c1, t2.c1, t1.c3
+               One-Time Filter: (CURRENT_USER = SESSION_USER)
+               ->  Hash Join
+                     Output: t1.c1, t1.c3, t2.c1
+                     Hash Cond: (t2.c1 = t1.c1)
+                     ->  Foreign Scan on public.ft2 t2
+                           Output: t2.c1
+                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+                     ->  Hash
+                           Output: t1.c1, t1.c3
+                           ->  Foreign Scan on public.ft1 t1
+                                 Output: t1.c1, t1.c3
+                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
+(19 rows)
+
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
 -- unable to push {ft1, ft2}
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index b54903ad8f..ef3ef4e2ed 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,6 +640,9 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index cd80e61fd7..092be6fbfc 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,6 +24,7 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
+#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -325,9 +326,15 @@ add_paths_to_joinrel(PlannerInfo *root,
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
+	 *
+	 * createplan.c doesn't currently support handling of pseudoconstant
+	 * clauses in ForeignScan nodes that push down joins to remote servers; if
+	 * the restrictlist has such clauses then disallow the FDW to consider
+	 * pushing down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths)
+		joinrel->fdwroutine->GetForeignJoinPaths &&
+		!has_pseudoconstant_clauses(root, restrictlist))
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index d6d26a2b51..537c3d4373 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -508,6 +508,36 @@ extract_actual_clauses(List *restrictinfo_list,
 	return result;
 }
 
+/*
+ * has_pseudoconstant_clauses
+ *
+ * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
+ *
+ * This is used when we determine whether to give the FDW a chance to push
+ * down joins to the remote server in add_paths_to_joinrel().
+ */
+bool
+has_pseudoconstant_clauses(PlannerInfo *root,
+						   List *restrictinfo_list)
+{
+	ListCell   *l;
+
+	/* No need to look if we know there are no pseudoconstants */
+	if (!root->hasPseudoConstantQuals)
+		return false;
+
+	/* See if there are pseudoconstants in the RestrictInfo list */
+	foreach(l, restrictinfo_list)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
+
+		if (rinfo->pseudoconstant &&
+			!rinfo_is_constant_true(rinfo))
+			return true;
+	}
+	return false;
+}
+
 /*
  * extract_actual_join_clauses
  *
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index e140e619ac..14cdce750c 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,6 +43,8 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
+extern bool has_pseudoconstant_clauses(PlannerInfo *root,
+									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index c8c4614b54..98df6371c0 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,6 +2316,32 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
+                                  QUERY PLAN                                   
+-------------------------------------------------------------------------------
+ Limit
+   Output: t1.c1, t2.c1, t1.c3
+   ->  Sort
+         Output: t1.c1, t2.c1, t1.c3
+         Sort Key: t1.c3, t1.c1
+         ->  Result
+               Output: t1.c1, t2.c1, t1.c3
+               One-Time Filter: (CURRENT_USER = SESSION_USER)
+               ->  Hash Join
+                     Output: t1.c1, t1.c3, t2.c1
+                     Hash Cond: (t2.c1 = t1.c1)
+                     ->  Foreign Scan on public.ft2 t2
+                           Output: t2.c1
+                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+                     ->  Hash
+                           Output: t1.c1, t1.c3
+                           ->  Foreign Scan on public.ft1 t1
+                                 Output: t1.c1, t1.c3
+                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
+(19 rows)
+
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
 -- unable to push {ft1, ft2}
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index b54903ad8f..ef3ef4e2ed 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,6 +640,9 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 5ba266fdb6..98713f5fd6 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,6 +24,7 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
+#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -130,6 +131,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 {
 	JoinPathExtraData extra;
 	bool		mergejoin_allowed = true;
+	bool		consider_join_pushdown = false;
 	ListCell   *lc;
 	Relids		joinrelids;
 
@@ -321,13 +323,26 @@ add_paths_to_joinrel(PlannerInfo *root,
 		hash_inner_and_outer(root, joinrel, outerrel, innerrel,
 							 jointype, &extra);
 
+	/*
+	 * createplan.c doesn't currently support handling of pseudoconstant
+	 * clauses in ForeignScan/CustomScan nodes that push down joins; if the
+	 * restrictlist has such clauses then disallow extensions to consider
+	 * pushing down joins.
+	 */
+	if ((joinrel->fdwroutine &&
+		 joinrel->fdwroutine->GetForeignJoinPaths) ||
+		set_join_pathlist_hook)
+		consider_join_pushdown = !has_pseudoconstant_clauses(root,
+															 restrictlist);
+
 	/*
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths)
+		joinrel->fdwroutine->GetForeignJoinPaths &&
+		consider_join_pushdown)
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
@@ -335,7 +350,8 @@ add_paths_to_joinrel(PlannerInfo *root,
 	/*
 	 * 6. Finally, give extensions a chance to manipulate the path list.
 	 */
-	if (set_join_pathlist_hook)
+	if (set_join_pathlist_hook &&
+		consider_join_pushdown)
 		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
 							   jointype, &extra);
 }
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index d6d26a2b51..701f8812c9 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -508,6 +508,36 @@ extract_actual_clauses(List *restrictinfo_list,
 	return result;
 }
 
+/*
+ * has_pseudoconstant_clauses
+ *
+ * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
+ *
+ * This is used when we determine whether to allow extensions to consider
+ * pushing down joins to remote sides in add_paths_to_joinrel().
+ */
+bool
+has_pseudoconstant_clauses(PlannerInfo *root,
+						   List *restrictinfo_list)
+{
+	ListCell   *l;
+
+	/* No need to look if we know there are no pseudoconstants */
+	if (!root->hasPseudoConstantQuals)
+		return false;
+
+	/* See if there are pseudoconstants in the RestrictInfo list */
+	foreach(l, restrictinfo_list)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
+
+		if (rinfo->pseudoconstant &&
+			!rinfo_is_constant_true(rinfo))
+			return true;
+	}
+	return false;
+}
+
 /*
  * extract_actual_join_clauses
  *
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index e140e619ac..14cdce750c 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,6 +43,8 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
+extern bool has_pseudoconstant_clauses(PlannerInfo *root,
+									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 852b5b4707..f6d3b8ec08 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,6 +2316,32 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
+                                  QUERY PLAN                                   
+-------------------------------------------------------------------------------
+ Limit
+   Output: t1.c1, t2.c1, t1.c3
+   ->  Sort
+         Output: t1.c1, t2.c1, t1.c3
+         Sort Key: t1.c3, t1.c1
+         ->  Result
+               Output: t1.c1, t2.c1, t1.c3
+               One-Time Filter: (CURRENT_USER = SESSION_USER)
+               ->  Hash Join
+                     Output: t1.c1, t1.c3, t2.c1
+                     Hash Cond: (t2.c1 = t1.c1)
+                     ->  Foreign Scan on public.ft2 t2
+                           Output: t2.c1
+                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+                     ->  Hash
+                           Output: t1.c1, t1.c3
+                           ->  Foreign Scan on public.ft1 t1
+                                 Output: t1.c1, t1.c3
+                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
+(19 rows)
+
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
 -- unable to push {ft1, ft2}
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 2fe8abc7af..436feee396 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,6 +640,9 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
+-- join with pseudoconstant quals, not pushed down.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index f047ad9ba4..c2034268ca 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,6 +24,7 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
+#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -130,6 +131,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 {
 	JoinPathExtraData extra;
 	bool		mergejoin_allowed = true;
+	bool		consider_join_pushdown = false;
 	ListCell   *lc;
 	Relids		joinrelids;
 
@@ -321,13 +323,26 @@ add_paths_to_joinrel(PlannerInfo *root,
 		hash_inner_and_outer(root, joinrel, outerrel, innerrel,
 							 jointype, &extra);
 
+	/*
+	 * createplan.c does not currently support handling of pseudoconstant
+	 * clauses in ForeignScan/CustomScan nodes that push down joins; if the
+	 * restrictlist has such clauses then disallow extensions to consider
+	 * pushing down joins.
+	 */
+	if ((joinrel->fdwroutine &&
+		 joinrel->fdwroutine->GetForeignJoinPaths) ||
+		set_join_pathlist_hook)
+		consider_join_pushdown = !has_pseudoconstant_clauses(root,
+															 restrictlist);
+
 	/*
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths)
+		joinrel->fdwroutine->GetForeignJoinPaths &&
+		consider_join_pushdown)
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
@@ -335,7 +350,8 @@ add_paths_to_joinrel(PlannerInfo *root,
 	/*
 	 * 6. Finally, give extensions a chance to manipulate the path list.
 	 */
-	if (set_join_pathlist_hook)
+	if (set_join_pathlist_hook &&
+		consider_join_pushdown)
 		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
 							   jointype, &extra);
 }
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index d6d26a2b51..701f8812c9 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -508,6 +508,36 @@ extract_actual_clauses(List *restrictinfo_list,
 	return result;
 }
 
+/*
+ * has_pseudoconstant_clauses
+ *
+ * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
+ *
+ * This is used when we determine whether to allow extensions to consider
+ * pushing down joins to remote sides in add_paths_to_joinrel().
+ */
+bool
+has_pseudoconstant_clauses(PlannerInfo *root,
+						   List *restrictinfo_list)
+{
+	ListCell   *l;
+
+	/* No need to look if we know there are no pseudoconstants */
+	if (!root->hasPseudoConstantQuals)
+		return false;
+
+	/* See if there are pseudoconstants in the RestrictInfo list */
+	foreach(l, restrictinfo_list)
+	{
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
+
+		if (rinfo->pseudoconstant &&
+			!rinfo_is_constant_true(rinfo))
+			return true;
+	}
+	return false;
+}
+
 /*
  * extract_actual_join_clauses
  *
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index e140e619ac..14cdce750c 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,6 +43,8 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
+extern bool has_pseudoconstant_clauses(PlannerInfo *root,
+									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index 9e330b9934..f14e6fe2e0 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -581,6 +581,7 @@ fileGetForeignPaths(PlannerInfo *root,
 									 NIL,	/* no pathkeys */
 									 baserel->lateral_relids,
 									 NULL,	/* no extra plan */
+									 NIL,
 									 coptions));
 
 	/*
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index f6d3b8ec08..77df7eb8e4 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,31 +2316,21 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-                                  QUERY PLAN                                   
--------------------------------------------------------------------------------
+                                                                                           QUERY PLAN                                                                                           
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3
-   ->  Sort
+   ->  Result
          Output: t1.c1, t2.c1, t1.c3
-         Sort Key: t1.c3, t1.c1
-         ->  Result
-               Output: t1.c1, t2.c1, t1.c3
-               One-Time Filter: (CURRENT_USER = SESSION_USER)
-               ->  Hash Join
-                     Output: t1.c1, t1.c3, t2.c1
-                     Hash Cond: (t2.c1 = t1.c1)
-                     ->  Foreign Scan on public.ft2 t2
-                           Output: t2.c1
-                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
-                     ->  Hash
-                           Output: t1.c1, t1.c3
-                           ->  Foreign Scan on public.ft1 t1
-                                 Output: t1.c1, t1.c3
-                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
-(19 rows)
+         One-Time Filter: (CURRENT_USER = SESSION_USER)
+         ->  Foreign Scan
+               Output: t1.c1, t1.c3, t2.c1
+               Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
+               Remote SQL: SELECT r1."C 1", r2."C 1", r1.c3 FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r2."C 1" = r1."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
+(9 rows)
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index c5cada55fb..2804a13313 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -524,7 +524,7 @@ static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
 											  RelOptInfo *rel);
 static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
 static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-											Path *epq_path);
+											Path *epq_path, List *restrictlist);
 static void add_foreign_grouping_paths(PlannerInfo *root,
 									   RelOptInfo *input_rel,
 									   RelOptInfo *grouped_rel,
@@ -1034,11 +1034,12 @@ postgresGetForeignPaths(PlannerInfo *root,
 								   NIL, /* no pathkeys */
 								   baserel->lateral_relids,
 								   NULL,	/* no extra plan */
+								   NIL,
 								   NIL);	/* no fdw_private list */
 	add_path(baserel, (Path *) path);
 
 	/* Add paths with pathkeys */
-	add_paths_with_pathkeys_for_rel(root, baserel, NULL);
+	add_paths_with_pathkeys_for_rel(root, baserel, NULL, NIL);
 
 	/*
 	 * If we're not using remote estimates, stop here.  We have no way to
@@ -1206,6 +1207,7 @@ postgresGetForeignPaths(PlannerInfo *root,
 									   NIL, /* no pathkeys */
 									   param_info->ppi_req_outer,
 									   NULL,
+									   NIL,
 									   NIL);	/* no fdw_private list */
 		add_path(baserel, (Path *) path);
 	}
@@ -5991,7 +5993,7 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
 
 static void
 add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-								Path *epq_path)
+								Path *epq_path, List *restrictlist)
 {
 	List	   *useful_pathkeys_list = NIL; /* List of all pathkeys */
 	ListCell   *lc;
@@ -6085,6 +6087,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											 useful_pathkeys,
 											 rel->lateral_relids,
 											 sorted_epq_path,
+											 NIL,
 											 NIL));
 		else
 			add_path(rel, (Path *)
@@ -6096,6 +6099,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											  useful_pathkeys,
 											  rel->lateral_relids,
 											  sorted_epq_path,
+											  restrictlist,
 											  NIL));
 	}
 }
@@ -6348,13 +6352,15 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
 										NIL,	/* no pathkeys */
 										joinrel->lateral_relids,
 										epq_path,
+										extra->restrictlist,
 										NIL);	/* no fdw_private */
 
 	/* Add generated path into joinrel by add_path(). */
 	add_path(joinrel, (Path *) joinpath);
 
 	/* Consider pathkeys for the join relation */
-	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path);
+	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path,
+									extra->restrictlist);
 
 	/* XXX Consider parameterized paths for the join relation */
 }
@@ -6735,6 +6741,7 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										  total_cost,
 										  NIL,	/* no pathkeys */
 										  NULL,
+										  NIL,
 										  NIL); /* no fdw_private */
 
 	/* Add generated path into grouped_rel by add_path(). */
@@ -6868,6 +6875,7 @@ add_foreign_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel,
 											 total_cost,
 											 root->sort_pathkeys,
 											 NULL,	/* no extra plan */
+											 NIL,
 											 fdw_private);
 
 	/* and add it to the ordered_rel */
@@ -6983,7 +6991,8 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 													   path->total_cost,
 													   path->pathkeys,
 													   NULL,	/* no extra plan */
-													   NULL);	/* no fdw_private */
+													   NIL,
+													   NIL);	/* no fdw_private */
 
 				/* and add it to the final_rel */
 				add_path(final_rel, (Path *) final_path);
@@ -7103,6 +7112,7 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										   total_cost,
 										   pathkeys,
 										   NULL,	/* no extra plan */
+										   NIL,
 										   fdw_private);
 
 	/* and add it to the final_rel */
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 436feee396..cfb1b57e33 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,7 +640,7 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
diff --git a/doc/src/sgml/custom-scan.sgml b/doc/src/sgml/custom-scan.sgml
index 93d96f2f56..d30aaeb024 100644
--- a/doc/src/sgml/custom-scan.sgml
+++ b/doc/src/sgml/custom-scan.sgml
@@ -62,6 +62,7 @@ typedef struct CustomPath
     Path      path;
     uint32    flags;
     List     *custom_paths;
+    List     *custom_restrictinfo;
     List     *custom_private;
     const CustomPathMethods *methods;
 } CustomPath;
@@ -85,6 +86,11 @@ typedef struct CustomPath
     An optional <structfield>custom_paths</structfield> is a list of <structname>Path</structname>
     nodes used by this custom-path node; these will be transformed into
     <structname>Plan</structname> nodes by planner.
+    As described below, custom paths can be created for join relations as
+    well.  In such a case, <structfield>custom_restrictinfo</structfield>
+    should be used to store a list of <structname>RestrictInfo</structname>
+    nodes to apply to the join, which will be used by planner to convert the
+    custom path to a finished plan.  Otherwise it should be NIL.
     <structfield>custom_private</structfield> can be used to store the custom path's
     private data.  Private data should be stored in a form that can be handled
     by <literal>nodeToString</literal>, so that debugging routines that attempt to
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index c2034268ca..f047ad9ba4 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,7 +24,6 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
-#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -131,7 +130,6 @@ add_paths_to_joinrel(PlannerInfo *root,
 {
 	JoinPathExtraData extra;
 	bool		mergejoin_allowed = true;
-	bool		consider_join_pushdown = false;
 	ListCell   *lc;
 	Relids		joinrelids;
 
@@ -323,26 +321,13 @@ add_paths_to_joinrel(PlannerInfo *root,
 		hash_inner_and_outer(root, joinrel, outerrel, innerrel,
 							 jointype, &extra);
 
-	/*
-	 * createplan.c does not currently support handling of pseudoconstant
-	 * clauses in ForeignScan/CustomScan nodes that push down joins; if the
-	 * restrictlist has such clauses then disallow extensions to consider
-	 * pushing down joins.
-	 */
-	if ((joinrel->fdwroutine &&
-		 joinrel->fdwroutine->GetForeignJoinPaths) ||
-		set_join_pathlist_hook)
-		consider_join_pushdown = !has_pseudoconstant_clauses(root,
-															 restrictlist);
-
 	/*
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths &&
-		consider_join_pushdown)
+		joinrel->fdwroutine->GetForeignJoinPaths)
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
@@ -350,8 +335,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 	/*
 	 * 6. Finally, give extensions a chance to manipulate the path list.
 	 */
-	if (set_join_pathlist_hook &&
-		consider_join_pushdown)
+	if (set_join_pathlist_hook)
 		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
 							   jointype, &extra);
 }
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index af48109058..f40910a8bb 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -599,8 +599,26 @@ create_scan_plan(PlannerInfo *root, Path *best_path, int flags)
 	 * Detect whether we have any pseudoconstant quals to deal with.  Then, if
 	 * we'll need a gating Result node, it will be able to project, so there
 	 * are no requirements on the child's tlist.
+	 *
+	 * If replacing a join, the FDW or custom scan provider would have stored
+	 * the joinrestrictinfo list in the best path; check against it in that
+	 * case.
 	 */
-	gating_clauses = get_gating_quals(root, scan_clauses);
+	if (IS_JOIN_REL(rel))
+	{
+		List	   *join_clauses;
+
+		Assert(best_path->pathtype == T_ForeignScan ||
+			   best_path->pathtype == T_CustomScan);
+		if (best_path->pathtype == T_ForeignScan)
+			join_clauses = ((ForeignPath *) best_path)->fdw_restrictinfo;
+		else
+			join_clauses = ((CustomPath *) best_path)->custom_restrictinfo;
+
+		gating_clauses = get_gating_quals(root, join_clauses);
+	}
+	else
+		gating_clauses = get_gating_quals(root, scan_clauses);
 	if (gating_clauses)
 		flags = 0;
 
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index f123fcb41e..fb3b854c55 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2229,6 +2229,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 						List *pathkeys,
 						Relids required_outer,
 						Path *fdw_outerpath,
+						List *fdw_restrictinfo,
 						List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2250,6 +2251,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2273,6 +2275,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 						 List *pathkeys,
 						 Relids required_outer,
 						 Path *fdw_outerpath,
+						 List *fdw_restrictinfo,
 						 List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2300,6 +2303,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2322,6 +2326,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 						  double rows, Cost startup_cost, Cost total_cost,
 						  List *pathkeys,
 						  Path *fdw_outerpath,
+						  List *fdw_restrictinfo,
 						  List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2345,6 +2350,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index 701f8812c9..d6d26a2b51 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -508,36 +508,6 @@ extract_actual_clauses(List *restrictinfo_list,
 	return result;
 }
 
-/*
- * has_pseudoconstant_clauses
- *
- * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
- *
- * This is used when we determine whether to allow extensions to consider
- * pushing down joins to remote sides in add_paths_to_joinrel().
- */
-bool
-has_pseudoconstant_clauses(PlannerInfo *root,
-						   List *restrictinfo_list)
-{
-	ListCell   *l;
-
-	/* No need to look if we know there are no pseudoconstants */
-	if (!root->hasPseudoConstantQuals)
-		return false;
-
-	/* See if there are pseudoconstants in the RestrictInfo list */
-	foreach(l, restrictinfo_list)
-	{
-		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
-
-		if (rinfo->pseudoconstant &&
-			!rinfo_is_constant_true(rinfo))
-			return true;
-	}
-	return false;
-}
-
 /*
  * extract_actual_join_clauses
  *
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index c17b53f7ad..50c1f4f01a 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1822,6 +1822,10 @@ typedef struct SubqueryScanPath
  * ForeignPath represents a potential scan of a foreign table, foreign join
  * or foreign upper-relation.
  *
+ * In the case of foreign join, fdw_restrictinfo stores the RestrictInfos to
+ * apply to this join.  It is needed because we need to extract gating clauses
+ * from it.
+ *
  * fdw_private stores FDW private data about the scan.  While fdw_private is
  * not actually touched by the core code during normal operations, it's
  * generally a good idea to use a representation that can be dumped by
@@ -1832,6 +1836,7 @@ typedef struct ForeignPath
 {
 	Path		path;
 	Path	   *fdw_outerpath;
+	List	   *fdw_restrictinfo;
 	List	   *fdw_private;
 } ForeignPath;
 
@@ -1862,6 +1867,7 @@ typedef struct CustomPath
 	uint32		flags;			/* mask of CUSTOMPATH_* flags, see
 								 * nodes/extensible.h */
 	List	   *custom_paths;	/* list of child Path nodes, if any */
+	List	   *custom_restrictinfo;
 	List	   *custom_private;
 	const struct CustomPathMethods *methods;
 } CustomPath;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 001e75b5b7..6e557bebc4 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -128,6 +128,7 @@ extern ForeignPath *create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 											List *pathkeys,
 											Relids required_outer,
 											Path *fdw_outerpath,
+											List *fdw_restrictinfo,
 											List *fdw_private);
 extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 PathTarget *target,
@@ -135,12 +136,14 @@ extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 List *pathkeys,
 											 Relids required_outer,
 											 Path *fdw_outerpath,
+											 List *fdw_restrictinfo,
 											 List *fdw_private);
 extern ForeignPath *create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 											  PathTarget *target,
 											  double rows, Cost startup_cost, Cost total_cost,
 											  List *pathkeys,
 											  Path *fdw_outerpath,
+											  List *fdw_restrictinfo,
 											  List *fdw_private);
 
 extern Relids calc_nestloop_required_outer(Relids outerrelids,
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index 14cdce750c..e140e619ac 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,8 +43,6 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
-extern bool has_pseudoconstant_clauses(PlannerInfo *root,
-									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index 9e330b9934..f14e6fe2e0 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -581,6 +581,7 @@ fileGetForeignPaths(PlannerInfo *root,
 									 NIL,	/* no pathkeys */
 									 baserel->lateral_relids,
 									 NULL,	/* no extra plan */
+									 NIL,
 									 coptions));
 
 	/*
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index f6d3b8ec08..77df7eb8e4 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,31 +2316,21 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-                                  QUERY PLAN                                   
--------------------------------------------------------------------------------
+                                                                                           QUERY PLAN                                                                                           
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3
-   ->  Sort
+   ->  Result
          Output: t1.c1, t2.c1, t1.c3
-         Sort Key: t1.c3, t1.c1
-         ->  Result
-               Output: t1.c1, t2.c1, t1.c3
-               One-Time Filter: (CURRENT_USER = SESSION_USER)
-               ->  Hash Join
-                     Output: t1.c1, t1.c3, t2.c1
-                     Hash Cond: (t2.c1 = t1.c1)
-                     ->  Foreign Scan on public.ft2 t2
-                           Output: t2.c1
-                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
-                     ->  Hash
-                           Output: t1.c1, t1.c3
-                           ->  Foreign Scan on public.ft1 t1
-                                 Output: t1.c1, t1.c3
-                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
-(19 rows)
+         One-Time Filter: (CURRENT_USER = SESSION_USER)
+         ->  Foreign Scan
+               Output: t1.c1, t1.c3, t2.c1
+               Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
+               Remote SQL: SELECT r1."C 1", r2."C 1", r1.c3 FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r2."C 1" = r1."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
+(9 rows)
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index c5cada55fb..2804a13313 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -524,7 +524,7 @@ static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
 											  RelOptInfo *rel);
 static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
 static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-											Path *epq_path);
+											Path *epq_path, List *restrictlist);
 static void add_foreign_grouping_paths(PlannerInfo *root,
 									   RelOptInfo *input_rel,
 									   RelOptInfo *grouped_rel,
@@ -1034,11 +1034,12 @@ postgresGetForeignPaths(PlannerInfo *root,
 								   NIL, /* no pathkeys */
 								   baserel->lateral_relids,
 								   NULL,	/* no extra plan */
+								   NIL,
 								   NIL);	/* no fdw_private list */
 	add_path(baserel, (Path *) path);
 
 	/* Add paths with pathkeys */
-	add_paths_with_pathkeys_for_rel(root, baserel, NULL);
+	add_paths_with_pathkeys_for_rel(root, baserel, NULL, NIL);
 
 	/*
 	 * If we're not using remote estimates, stop here.  We have no way to
@@ -1206,6 +1207,7 @@ postgresGetForeignPaths(PlannerInfo *root,
 									   NIL, /* no pathkeys */
 									   param_info->ppi_req_outer,
 									   NULL,
+									   NIL,
 									   NIL);	/* no fdw_private list */
 		add_path(baserel, (Path *) path);
 	}
@@ -5991,7 +5993,7 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
 
 static void
 add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-								Path *epq_path)
+								Path *epq_path, List *restrictlist)
 {
 	List	   *useful_pathkeys_list = NIL; /* List of all pathkeys */
 	ListCell   *lc;
@@ -6085,6 +6087,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											 useful_pathkeys,
 											 rel->lateral_relids,
 											 sorted_epq_path,
+											 NIL,
 											 NIL));
 		else
 			add_path(rel, (Path *)
@@ -6096,6 +6099,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											  useful_pathkeys,
 											  rel->lateral_relids,
 											  sorted_epq_path,
+											  restrictlist,
 											  NIL));
 	}
 }
@@ -6348,13 +6352,15 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
 										NIL,	/* no pathkeys */
 										joinrel->lateral_relids,
 										epq_path,
+										extra->restrictlist,
 										NIL);	/* no fdw_private */
 
 	/* Add generated path into joinrel by add_path(). */
 	add_path(joinrel, (Path *) joinpath);
 
 	/* Consider pathkeys for the join relation */
-	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path);
+	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path,
+									extra->restrictlist);
 
 	/* XXX Consider parameterized paths for the join relation */
 }
@@ -6735,6 +6741,7 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										  total_cost,
 										  NIL,	/* no pathkeys */
 										  NULL,
+										  NIL,
 										  NIL); /* no fdw_private */
 
 	/* Add generated path into grouped_rel by add_path(). */
@@ -6868,6 +6875,7 @@ add_foreign_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel,
 											 total_cost,
 											 root->sort_pathkeys,
 											 NULL,	/* no extra plan */
+											 NIL,
 											 fdw_private);
 
 	/* and add it to the ordered_rel */
@@ -6983,7 +6991,8 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 													   path->total_cost,
 													   path->pathkeys,
 													   NULL,	/* no extra plan */
-													   NULL);	/* no fdw_private */
+													   NIL,
+													   NIL);	/* no fdw_private */
 
 				/* and add it to the final_rel */
 				add_path(final_rel, (Path *) final_path);
@@ -7103,6 +7112,7 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										   total_cost,
 										   pathkeys,
 										   NULL,	/* no extra plan */
+										   NIL,
 										   fdw_private);
 
 	/* and add it to the final_rel */
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 436feee396..cfb1b57e33 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,7 +640,7 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
diff --git a/doc/src/sgml/custom-scan.sgml b/doc/src/sgml/custom-scan.sgml
index 93d96f2f56..d30aaeb024 100644
--- a/doc/src/sgml/custom-scan.sgml
+++ b/doc/src/sgml/custom-scan.sgml
@@ -62,6 +62,7 @@ typedef struct CustomPath
     Path      path;
     uint32    flags;
     List     *custom_paths;
+    List     *custom_restrictinfo;
     List     *custom_private;
     const CustomPathMethods *methods;
 } CustomPath;
@@ -85,6 +86,11 @@ typedef struct CustomPath
     An optional <structfield>custom_paths</structfield> is a list of <structname>Path</structname>
     nodes used by this custom-path node; these will be transformed into
     <structname>Plan</structname> nodes by planner.
+    As described below, custom paths can be created for join relations as
+    well.  In such a case, <structfield>custom_restrictinfo</structfield>
+    should be used to store a list of <structname>RestrictInfo</structname>
+    nodes to apply to the join, which will be used by planner to convert the
+    custom path to a finished plan.  Otherwise it should be NIL.
     <structfield>custom_private</structfield> can be used to store the custom path's
     private data.  Private data should be stored in a form that can be handled
     by <literal>nodeToString</literal>, so that debugging routines that attempt to
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 4b58936fa4..f047ad9ba4 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,7 +24,6 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
-#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -131,7 +130,6 @@ add_paths_to_joinrel(PlannerInfo *root,
 {
 	JoinPathExtraData extra;
 	bool		mergejoin_allowed = true;
-	bool		consider_join_pushdown = false;
 	ListCell   *lc;
 	Relids		joinrelids;
 
@@ -323,25 +321,13 @@ add_paths_to_joinrel(PlannerInfo *root,
 		hash_inner_and_outer(root, joinrel, outerrel, innerrel,
 							 jointype, &extra);
 
-	/*
-	 * createplan.c does not currently support handling of pseudoconstant
-	 * clauses assigned to joins pushed down by extensions; check if the
-	 * restrictlist has such clauses, and if so, disallow pushing down joins.
-	 */
-	if ((joinrel->fdwroutine &&
-		 joinrel->fdwroutine->GetForeignJoinPaths) ||
-		set_join_pathlist_hook)
-		consider_join_pushdown = !has_pseudoconstant_clauses(root,
-															 restrictlist);
-
 	/*
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths &&
-		consider_join_pushdown)
+		joinrel->fdwroutine->GetForeignJoinPaths)
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
@@ -349,8 +335,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 	/*
 	 * 6. Finally, give extensions a chance to manipulate the path list.
 	 */
-	if (set_join_pathlist_hook &&
-		consider_join_pushdown)
+	if (set_join_pathlist_hook)
 		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
 							   jointype, &extra);
 }
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index af48109058..ad811a2cd5 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -599,8 +599,27 @@ create_scan_plan(PlannerInfo *root, Path *best_path, int flags)
 	 * Detect whether we have any pseudoconstant quals to deal with.  Then, if
 	 * we'll need a gating Result node, it will be able to project, so there
 	 * are no requirements on the child's tlist.
+	 *
+	 * If this replaces a join, it must be a foreign scan or a custom scan,
+	 * and the FDW or custom scan provider would have stored in the best path
+	 * the list of RestrictInfo nodes to apply to the join; check against that
+	 * list in that case.
 	 */
-	gating_clauses = get_gating_quals(root, scan_clauses);
+	if (IS_JOIN_REL(rel))
+	{
+		List	   *join_clauses;
+
+		Assert(best_path->pathtype == T_ForeignScan ||
+			   best_path->pathtype == T_CustomScan);
+		if (best_path->pathtype == T_ForeignScan)
+			join_clauses = ((ForeignPath *) best_path)->fdw_restrictinfo;
+		else
+			join_clauses = ((CustomPath *) best_path)->custom_restrictinfo;
+
+		gating_clauses = get_gating_quals(root, join_clauses);
+	}
+	else
+		gating_clauses = get_gating_quals(root, scan_clauses);
 	if (gating_clauses)
 		flags = 0;
 
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index f123fcb41e..da2ae771d5 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2229,6 +2229,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 						List *pathkeys,
 						Relids required_outer,
 						Path *fdw_outerpath,
+						List *fdw_restrictinfo,
 						List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2250,6 +2251,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2273,6 +2275,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 						 List *pathkeys,
 						 Relids required_outer,
 						 Path *fdw_outerpath,
+						 List *fdw_restrictinfo,
 						 List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2300,6 +2303,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2322,6 +2326,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 						  double rows, Cost startup_cost, Cost total_cost,
 						  List *pathkeys,
 						  Path *fdw_outerpath,
+						  List *fdw_restrictinfo,
 						  List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2345,6 +2350,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -4150,6 +4156,7 @@ do { \
 				FLAT_COPY_PATH(fpath, path, ForeignPath);
 				if (fpath->fdw_outerpath)
 					REPARAMETERIZE_CHILD_PATH(fpath->fdw_outerpath);
+				ADJUST_CHILD_ATTRS(fpath->fdw_restrictinfo);
 
 				/* Hand over to FDW if needed. */
 				rfpc_func =
@@ -4167,6 +4174,7 @@ do { \
 
 				FLAT_COPY_PATH(cpath, path, CustomPath);
 				REPARAMETERIZE_CHILD_PATH_LIST(cpath->custom_paths);
+				ADJUST_CHILD_ATTRS(cpath->custom_restrictinfo);
 				if (cpath->methods &&
 					cpath->methods->ReparameterizeCustomPathByChild)
 					cpath->custom_private =
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index c1fbbb6bfe..d6d26a2b51 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -549,36 +549,6 @@ extract_actual_join_clauses(List *restrictinfo_list,
 	}
 }
 
-/*
- * has_pseudoconstant_clauses
- *
- * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
- *
- * This is used when we determine whether to allow extensions to consider
- * pushing down joins in add_paths_to_joinrel().
- */
-bool
-has_pseudoconstant_clauses(PlannerInfo *root,
-						   List *restrictinfo_list)
-{
-	ListCell   *l;
-
-	/* No need to look if we know there are no pseudoconstants */
-	if (!root->hasPseudoConstantQuals)
-		return false;
-
-	/* See if there are pseudoconstants in the RestrictInfo list */
-	foreach(l, restrictinfo_list)
-	{
-		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
-
-		if (rinfo->pseudoconstant &&
-			!rinfo_is_constant_true(rinfo))
-			return true;
-	}
-	return false;
-}
-
 /*
  * join_clause_is_movable_to
  *		Test whether a join clause is a safe candidate for parameterization
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index c17b53f7ad..50c1f4f01a 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1822,6 +1822,10 @@ typedef struct SubqueryScanPath
  * ForeignPath represents a potential scan of a foreign table, foreign join
  * or foreign upper-relation.
  *
+ * In the case of foreign join, fdw_restrictinfo stores the RestrictInfos to
+ * apply to this join.  It is needed because we need to extract gating clauses
+ * from it.
+ *
  * fdw_private stores FDW private data about the scan.  While fdw_private is
  * not actually touched by the core code during normal operations, it's
  * generally a good idea to use a representation that can be dumped by
@@ -1832,6 +1836,7 @@ typedef struct ForeignPath
 {
 	Path		path;
 	Path	   *fdw_outerpath;
+	List	   *fdw_restrictinfo;
 	List	   *fdw_private;
 } ForeignPath;
 
@@ -1862,6 +1867,7 @@ typedef struct CustomPath
 	uint32		flags;			/* mask of CUSTOMPATH_* flags, see
 								 * nodes/extensible.h */
 	List	   *custom_paths;	/* list of child Path nodes, if any */
+	List	   *custom_restrictinfo;
 	List	   *custom_private;
 	const struct CustomPathMethods *methods;
 } CustomPath;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 001e75b5b7..6e557bebc4 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -128,6 +128,7 @@ extern ForeignPath *create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 											List *pathkeys,
 											Relids required_outer,
 											Path *fdw_outerpath,
+											List *fdw_restrictinfo,
 											List *fdw_private);
 extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 PathTarget *target,
@@ -135,12 +136,14 @@ extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 List *pathkeys,
 											 Relids required_outer,
 											 Path *fdw_outerpath,
+											 List *fdw_restrictinfo,
 											 List *fdw_private);
 extern ForeignPath *create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 											  PathTarget *target,
 											  double rows, Cost startup_cost, Cost total_cost,
 											  List *pathkeys,
 											  Path *fdw_outerpath,
+											  List *fdw_restrictinfo,
 											  List *fdw_private);
 
 extern Relids calc_nestloop_required_outer(Relids outerrelids,
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index 14cdce750c..e140e619ac 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,8 +43,6 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
-extern bool has_pseudoconstant_clauses(PlannerInfo *root,
-									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index 9e330b9934..2189be8a3c 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -581,6 +581,7 @@ fileGetForeignPaths(PlannerInfo *root,
 									 NIL,	/* no pathkeys */
 									 baserel->lateral_relids,
 									 NULL,	/* no extra plan */
+									 NIL,	/* no fdw_restrictinfo list */
 									 coptions));
 
 	/*
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index f6d3b8ec08..77df7eb8e4 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -2316,31 +2316,21 @@ SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
    1
 (10 rows)
 
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-                                  QUERY PLAN                                   
--------------------------------------------------------------------------------
+                                                                                           QUERY PLAN                                                                                           
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3
-   ->  Sort
+   ->  Result
          Output: t1.c1, t2.c1, t1.c3
-         Sort Key: t1.c3, t1.c1
-         ->  Result
-               Output: t1.c1, t2.c1, t1.c3
-               One-Time Filter: (CURRENT_USER = SESSION_USER)
-               ->  Hash Join
-                     Output: t1.c1, t1.c3, t2.c1
-                     Hash Cond: (t2.c1 = t1.c1)
-                     ->  Foreign Scan on public.ft2 t2
-                           Output: t2.c1
-                           Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
-                     ->  Hash
-                           Output: t1.c1, t1.c3
-                           ->  Foreign Scan on public.ft1 t1
-                                 Output: t1.c1, t1.c3
-                                 Remote SQL: SELECT "C 1", c3 FROM "S 1"."T 1"
-(19 rows)
+         One-Time Filter: (CURRENT_USER = SESSION_USER)
+         ->  Foreign Scan
+               Output: t1.c1, t1.c3, t2.c1
+               Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
+               Remote SQL: SELECT r1."C 1", r2."C 1", r1.c3 FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r2."C 1" = r1."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
+(9 rows)
 
 -- non-Var items in targetlist of the nullable rel of a join preventing
 -- push-down in some cases
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index c5cada55fb..ef58b8b0ea 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -524,7 +524,7 @@ static List *get_useful_pathkeys_for_relation(PlannerInfo *root,
 											  RelOptInfo *rel);
 static List *get_useful_ecs_for_relation(PlannerInfo *root, RelOptInfo *rel);
 static void add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-											Path *epq_path);
+											Path *epq_path, List *restrictlist);
 static void add_foreign_grouping_paths(PlannerInfo *root,
 									   RelOptInfo *input_rel,
 									   RelOptInfo *grouped_rel,
@@ -1034,11 +1034,12 @@ postgresGetForeignPaths(PlannerInfo *root,
 								   NIL, /* no pathkeys */
 								   baserel->lateral_relids,
 								   NULL,	/* no extra plan */
+								   NIL, /* no fdw_restrictinfo list */
 								   NIL);	/* no fdw_private list */
 	add_path(baserel, (Path *) path);
 
 	/* Add paths with pathkeys */
-	add_paths_with_pathkeys_for_rel(root, baserel, NULL);
+	add_paths_with_pathkeys_for_rel(root, baserel, NULL, NIL);
 
 	/*
 	 * If we're not using remote estimates, stop here.  We have no way to
@@ -1206,6 +1207,7 @@ postgresGetForeignPaths(PlannerInfo *root,
 									   NIL, /* no pathkeys */
 									   param_info->ppi_req_outer,
 									   NULL,
+									   NIL, /* no fdw_restrictinfo list */
 									   NIL);	/* no fdw_private list */
 		add_path(baserel, (Path *) path);
 	}
@@ -5991,7 +5993,7 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
 
 static void
 add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
-								Path *epq_path)
+								Path *epq_path, List *restrictlist)
 {
 	List	   *useful_pathkeys_list = NIL; /* List of all pathkeys */
 	ListCell   *lc;
@@ -6085,6 +6087,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											 useful_pathkeys,
 											 rel->lateral_relids,
 											 sorted_epq_path,
+											 NIL,	/* no fdw_restrictinfo list */
 											 NIL));
 		else
 			add_path(rel, (Path *)
@@ -6096,6 +6099,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
 											  useful_pathkeys,
 											  rel->lateral_relids,
 											  sorted_epq_path,
+											  restrictlist,
 											  NIL));
 	}
 }
@@ -6348,13 +6352,15 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
 										NIL,	/* no pathkeys */
 										joinrel->lateral_relids,
 										epq_path,
+										extra->restrictlist,
 										NIL);	/* no fdw_private */
 
 	/* Add generated path into joinrel by add_path(). */
 	add_path(joinrel, (Path *) joinpath);
 
 	/* Consider pathkeys for the join relation */
-	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path);
+	add_paths_with_pathkeys_for_rel(root, joinrel, epq_path,
+									extra->restrictlist);
 
 	/* XXX Consider parameterized paths for the join relation */
 }
@@ -6735,6 +6741,7 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										  total_cost,
 										  NIL,	/* no pathkeys */
 										  NULL,
+										  NIL,	/* no fdw_restrictinfo list */
 										  NIL); /* no fdw_private */
 
 	/* Add generated path into grouped_rel by add_path(). */
@@ -6868,6 +6875,7 @@ add_foreign_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel,
 											 total_cost,
 											 root->sort_pathkeys,
 											 NULL,	/* no extra plan */
+											 NIL,	/* no fdw_restrictinfo list */
 											 fdw_private);
 
 	/* and add it to the ordered_rel */
@@ -6983,7 +6991,8 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 													   path->total_cost,
 													   path->pathkeys,
 													   NULL,	/* no extra plan */
-													   NULL);	/* no fdw_private */
+													   NIL,	/* no fdw_restrictinfo list */
+													   NIL);	/* no fdw_private */
 
 				/* and add it to the final_rel */
 				add_path(final_rel, (Path *) final_path);
@@ -7103,6 +7112,7 @@ add_foreign_final_paths(PlannerInfo *root, RelOptInfo *input_rel,
 										   total_cost,
 										   pathkeys,
 										   NULL,	/* no extra plan */
+										   NIL,	/* no fdw_restrictinfo list */
 										   fdw_private);
 
 	/* and add it to the final_rel */
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 436feee396..cfb1b57e33 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -640,7 +640,7 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
 SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM ft1 t2, ft2 t3 WHERE t2.c1 = t3.c1 AND t2.c2 = t1.c2) q ORDER BY t1."C 1" OFFSET 10 LIMIT 10;
--- join with pseudoconstant quals, not pushed down.
+-- join with pseudoconstant quals
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1 AND CURRENT_USER = SESSION_USER) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
 
diff --git a/doc/src/sgml/custom-scan.sgml b/doc/src/sgml/custom-scan.sgml
index cd989e7d3c..6bf9647d95 100644
--- a/doc/src/sgml/custom-scan.sgml
+++ b/doc/src/sgml/custom-scan.sgml
@@ -62,6 +62,7 @@ typedef struct CustomPath
     Path      path;
     uint32    flags;
     List     *custom_paths;
+    List     *custom_restrictinfo;
     List     *custom_private;
     const CustomPathMethods *methods;
 } CustomPath;
@@ -85,6 +86,10 @@ typedef struct CustomPath
     An optional <structfield>custom_paths</structfield> is a list of <structname>Path</structname>
     nodes used by this custom-path node; these will be transformed into
     <structname>Plan</structname> nodes by planner.
+    As described below, custom paths can be created for join relations as
+    well.  In such a case, <structfield>custom_restrictinfo</structfield>
+    should be used to store the set of relevant join clauses for the join the
+    custom path replaces.  Otherwise it should be NIL.
     <structfield>custom_private</structfield> can be used to store the custom path's
     private data.  Private data should be stored in a form that can be handled
     by <literal>nodeToString</literal>, so that debugging routines that attempt to
@@ -114,6 +119,17 @@ extern PGDLLIMPORT set_join_pathlist_hook_type set_join_pathlist_hook;
    responsibility of the hook to minimize duplicated work.
   </para>
 
+  <para>
+   Note also that the set of relevant join clauses to apply to the join,
+   which is passed as <literal>extra-&gt;restrictlist</literal>, varies
+   depending on the combination of inner and outer relations.  A
+   <structname>CustomPath</structname> path generated for the
+   <literal>joinrel</literal> must contain the set of relevant join clauses
+   it uses, which will be used by the planner to convert the
+   <structname>CustomPath</structname> path into a plan, if it is selected
+   by the planner as the best path for the <literal>joinrel</literal>.
+  </para>
+
   <sect2 id="custom-scan-path-callbacks">
   <title>Custom Scan Path Callbacks</title>
 
diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml
index ac1717bc3c..72e005029d 100644
--- a/doc/src/sgml/fdwhandler.sgml
+++ b/doc/src/sgml/fdwhandler.sgml
@@ -333,6 +333,17 @@ GetForeignJoinPaths(PlannerInfo *root,
      the responsibility of the FDW to minimize duplicated work.
     </para>
 
+    <para>
+     Note also that the set of relevant join clauses to apply to the join,
+     which is passed as <literal>extra-&gt;restrictlist</literal>, varies
+     depending on the combination of inner and outer relations.  A
+     <structname>ForeignPath</structname> path generated for the
+     <literal>joinrel</literal> must contain the set of relevant join clauses
+     it uses, which will be used by the planner to convert the
+     <structname>ForeignPath</structname> path into a plan, if it is selected
+     by the planner as the best path for the <literal>joinrel</literal>.
+    </para>
+
     <para>
      If a <structname>ForeignPath</structname> path is chosen for the join, it will
      represent the entire join process; paths generated for the component
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 4b58936fa4..f047ad9ba4 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -24,7 +24,6 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
-#include "optimizer/restrictinfo.h"
 #include "utils/typcache.h"
 
 /* Hook for plugins to get control in add_paths_to_joinrel() */
@@ -131,7 +130,6 @@ add_paths_to_joinrel(PlannerInfo *root,
 {
 	JoinPathExtraData extra;
 	bool		mergejoin_allowed = true;
-	bool		consider_join_pushdown = false;
 	ListCell   *lc;
 	Relids		joinrelids;
 
@@ -323,25 +321,13 @@ add_paths_to_joinrel(PlannerInfo *root,
 		hash_inner_and_outer(root, joinrel, outerrel, innerrel,
 							 jointype, &extra);
 
-	/*
-	 * createplan.c does not currently support handling of pseudoconstant
-	 * clauses assigned to joins pushed down by extensions; check if the
-	 * restrictlist has such clauses, and if so, disallow pushing down joins.
-	 */
-	if ((joinrel->fdwroutine &&
-		 joinrel->fdwroutine->GetForeignJoinPaths) ||
-		set_join_pathlist_hook)
-		consider_join_pushdown = !has_pseudoconstant_clauses(root,
-															 restrictlist);
-
 	/*
 	 * 5. If inner and outer relations are foreign tables (or joins) belonging
 	 * to the same server and assigned to the same user to check access
 	 * permissions as, give the FDW a chance to push down joins.
 	 */
 	if (joinrel->fdwroutine &&
-		joinrel->fdwroutine->GetForeignJoinPaths &&
-		consider_join_pushdown)
+		joinrel->fdwroutine->GetForeignJoinPaths)
 		joinrel->fdwroutine->GetForeignJoinPaths(root, joinrel,
 												 outerrel, innerrel,
 												 jointype, &extra);
@@ -349,8 +335,7 @@ add_paths_to_joinrel(PlannerInfo *root,
 	/*
 	 * 6. Finally, give extensions a chance to manipulate the path list.
 	 */
-	if (set_join_pathlist_hook &&
-		consider_join_pushdown)
+	if (set_join_pathlist_hook)
 		set_join_pathlist_hook(root, joinrel, outerrel, innerrel,
 							   jointype, &extra);
 }
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index af48109058..ad811a2cd5 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -599,8 +599,27 @@ create_scan_plan(PlannerInfo *root, Path *best_path, int flags)
 	 * Detect whether we have any pseudoconstant quals to deal with.  Then, if
 	 * we'll need a gating Result node, it will be able to project, so there
 	 * are no requirements on the child's tlist.
+	 *
+	 * If this replaces a join, it must be a foreign scan or a custom scan,
+	 * and the FDW or custom scan provider would have stored in the best path
+	 * the list of RestrictInfo nodes to apply to the join; check against that
+	 * list in that case.
 	 */
-	gating_clauses = get_gating_quals(root, scan_clauses);
+	if (IS_JOIN_REL(rel))
+	{
+		List	   *join_clauses;
+
+		Assert(best_path->pathtype == T_ForeignScan ||
+			   best_path->pathtype == T_CustomScan);
+		if (best_path->pathtype == T_ForeignScan)
+			join_clauses = ((ForeignPath *) best_path)->fdw_restrictinfo;
+		else
+			join_clauses = ((CustomPath *) best_path)->custom_restrictinfo;
+
+		gating_clauses = get_gating_quals(root, join_clauses);
+	}
+	else
+		gating_clauses = get_gating_quals(root, scan_clauses);
 	if (gating_clauses)
 		flags = 0;
 
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 754f0b9f34..211ba65389 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2229,6 +2229,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 						List *pathkeys,
 						Relids required_outer,
 						Path *fdw_outerpath,
+						List *fdw_restrictinfo,
 						List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2250,6 +2251,7 @@ create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2273,6 +2275,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 						 List *pathkeys,
 						 Relids required_outer,
 						 Path *fdw_outerpath,
+						 List *fdw_restrictinfo,
 						 List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2300,6 +2303,7 @@ create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -2322,6 +2326,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 						  double rows, Cost startup_cost, Cost total_cost,
 						  List *pathkeys,
 						  Path *fdw_outerpath,
+						  List *fdw_restrictinfo,
 						  List *fdw_private)
 {
 	ForeignPath *pathnode = makeNode(ForeignPath);
@@ -2345,6 +2350,7 @@ create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->path.pathkeys = pathkeys;
 
 	pathnode->fdw_outerpath = fdw_outerpath;
+	pathnode->fdw_restrictinfo = fdw_restrictinfo;
 	pathnode->fdw_private = fdw_private;
 
 	return pathnode;
@@ -4149,6 +4155,8 @@ do { \
 				FLAT_COPY_PATH(fpath, path, ForeignPath);
 				if (fpath->fdw_outerpath)
 					REPARAMETERIZE_CHILD_PATH(fpath->fdw_outerpath);
+				if (fpath->fdw_restrictinfo)
+					ADJUST_CHILD_ATTRS(fpath->fdw_restrictinfo);
 
 				/* Hand over to FDW if needed. */
 				rfpc_func =
@@ -4166,6 +4174,8 @@ do { \
 
 				FLAT_COPY_PATH(cpath, path, CustomPath);
 				REPARAMETERIZE_CHILD_PATH_LIST(cpath->custom_paths);
+				if (cpath->custom_restrictinfo)
+					ADJUST_CHILD_ATTRS(cpath->custom_restrictinfo);
 				if (cpath->methods &&
 					cpath->methods->ReparameterizeCustomPathByChild)
 					cpath->custom_private =
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index c1fbbb6bfe..d6d26a2b51 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -549,36 +549,6 @@ extract_actual_join_clauses(List *restrictinfo_list,
 	}
 }
 
-/*
- * has_pseudoconstant_clauses
- *
- * Returns true if 'restrictinfo_list' includes pseudoconstant clauses.
- *
- * This is used when we determine whether to allow extensions to consider
- * pushing down joins in add_paths_to_joinrel().
- */
-bool
-has_pseudoconstant_clauses(PlannerInfo *root,
-						   List *restrictinfo_list)
-{
-	ListCell   *l;
-
-	/* No need to look if we know there are no pseudoconstants */
-	if (!root->hasPseudoConstantQuals)
-		return false;
-
-	/* See if there are pseudoconstants in the RestrictInfo list */
-	foreach(l, restrictinfo_list)
-	{
-		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
-
-		if (rinfo->pseudoconstant &&
-			!rinfo_is_constant_true(rinfo))
-			return true;
-	}
-	return false;
-}
-
 /*
  * join_clause_is_movable_to
  *		Test whether a join clause is a safe candidate for parameterization
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index a1dc1d07e1..e118aded2d 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1822,6 +1822,10 @@ typedef struct SubqueryScanPath
  * ForeignPath represents a potential scan of a foreign table, foreign join
  * or foreign upper-relation.
  *
+ * In the case of a foreign join, fdw_restrictinfo stores the RestrictInfos to
+ * apply to the join, which are used by createplan.c to get pseudoconstant
+ * clauses evaluated as one-time quals in a gating Result node.
+ *
  * fdw_private stores FDW private data about the scan.  While fdw_private is
  * not actually touched by the core code during normal operations, it's
  * generally a good idea to use a representation that can be dumped by
@@ -1832,6 +1836,7 @@ typedef struct ForeignPath
 {
 	Path		path;
 	Path	   *fdw_outerpath;
+	List	   *fdw_restrictinfo;
 	List	   *fdw_private;
 } ForeignPath;
 
@@ -1849,6 +1854,10 @@ typedef struct ForeignPath
  * relation by set_rel_pathlist_hook or set_join_pathlist_hook functions,
  * respectively.
  *
+ * In the case of a table join, custom_restrictinfo stores the RestrictInfos
+ * to apply to the join, which are used by createplan.c to get pseudoconstant
+ * clauses evaluated as one-time quals in a gating Result node.
+ *
  * Core code must avoid assuming that the CustomPath is only as large as
  * the structure declared here; providers are allowed to make it the first
  * element in a larger structure.  (Since the planner never copies Paths,
@@ -1865,6 +1874,7 @@ typedef struct CustomPath
 	uint32		flags;			/* mask of CUSTOMPATH_* flags, see
 								 * nodes/extensible.h */
 	List	   *custom_paths;	/* list of child Path nodes, if any */
+	List	   *custom_restrictinfo;
 	List	   *custom_private;
 	const struct CustomPathMethods *methods;
 } CustomPath;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 001e75b5b7..6e557bebc4 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -128,6 +128,7 @@ extern ForeignPath *create_foreignscan_path(PlannerInfo *root, RelOptInfo *rel,
 											List *pathkeys,
 											Relids required_outer,
 											Path *fdw_outerpath,
+											List *fdw_restrictinfo,
 											List *fdw_private);
 extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 PathTarget *target,
@@ -135,12 +136,14 @@ extern ForeignPath *create_foreign_join_path(PlannerInfo *root, RelOptInfo *rel,
 											 List *pathkeys,
 											 Relids required_outer,
 											 Path *fdw_outerpath,
+											 List *fdw_restrictinfo,
 											 List *fdw_private);
 extern ForeignPath *create_foreign_upper_path(PlannerInfo *root, RelOptInfo *rel,
 											  PathTarget *target,
 											  double rows, Cost startup_cost, Cost total_cost,
 											  List *pathkeys,
 											  Path *fdw_outerpath,
+											  List *fdw_restrictinfo,
 											  List *fdw_private);
 
 extern Relids calc_nestloop_required_outer(Relids outerrelids,
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index 14cdce750c..e140e619ac 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -43,8 +43,6 @@ extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
 										List **otherquals);
-extern bool has_pseudoconstant_clauses(PlannerInfo *root,
-									   List *restrictinfo_list);
 extern bool join_clause_is_movable_to(RestrictInfo *rinfo, RelOptInfo *baserel);
 extern bool join_clause_is_movable_into(RestrictInfo *rinfo,
 										Relids currentrelids,