postgres_fdw: Fix incorrect NULL handling in join pushdown.

something.* IS NOT NULL means that every attribute of the row is not
NULL, not that the row itself is non-NULL (e.g. because it's coming
from below an outer join.  Use (somevar.*)::pg_catalog.text IS NOT
NULL instead.

Ashutosh Bapat, per a report by Rushabh Lathia.  Reviewed by
Amit Langote and Etsuro Fujita.  Schema-qualification added by me.

3 files changed, 50 insertions, 25 deletions

diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index b0558edbf1..2ca0e0ccf1 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -1599,9 +1599,9 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 
 		if (qualify_col)
 		{
-			appendStringInfoString(buf, "CASE WHEN ");
+			appendStringInfoString(buf, "CASE WHEN (");
 			ADD_REL_QUALIFIER(buf, varno);
-			appendStringInfo(buf, "* IS NOT NULL THEN %u END", fetchval);
+			appendStringInfo(buf, "*)::pg_catalog.text IS NOT NULL THEN %u END", fetchval);
 		}
 		else
 			appendStringInfo(buf, "%u", fetchval);
@@ -1643,9 +1643,9 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		 */
 		if (qualify_col)
 		{
-			appendStringInfoString(buf, "CASE WHEN ");
+			appendStringInfoString(buf, "CASE WHEN (");
 			ADD_REL_QUALIFIER(buf, varno);
-			appendStringInfo(buf, "* IS NOT NULL THEN ");
+			appendStringInfo(buf, "*)::pg_catalog.text IS NOT NULL THEN ");
 		}
 
 		appendStringInfoString(buf, "ROW(");
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 73900d99c5..51bb63c700 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -1505,8 +1505,8 @@ SELECT t1.c1, t2.c1 FROM ft4 t1 FULL JOIN ft5 t2 ON (t1.c1 = t2.c1) WHERE (t1.c1
 -- tests whole-row reference for row marks
 EXPLAIN (COSTS false, VERBOSE)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR UPDATE OF t1;
-                                                                                                                                                                                                       QUERY PLAN                                                                                                                                                                                                        
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                                          QUERY PLAN                                                                                                                                                                                                                           
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
    ->  LockRows
@@ -1514,7 +1514,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
          ->  Foreign Scan
                Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
-               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1
+               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1
                ->  Merge Join
                      Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                      Merge Cond: (t1.c1 = t2.c1)
@@ -1549,8 +1549,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
 
 EXPLAIN (COSTS false, VERBOSE)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR UPDATE;
-                                                                                                                                                                                                                QUERY PLAN                                                                                                                                                                                                                
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                                                   QUERY PLAN                                                                                                                                                                                                                                   
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
    ->  LockRows
@@ -1558,7 +1558,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
          ->  Foreign Scan
                Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
-               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1 FOR UPDATE OF r2
+               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR UPDATE OF r1 FOR UPDATE OF r2
                ->  Merge Join
                      Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                      Merge Cond: (t1.c1 = t2.c1)
@@ -1594,8 +1594,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
 -- join two tables with FOR SHARE clause
 EXPLAIN (COSTS false, VERBOSE)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR SHARE OF t1;
-                                                                                                                                                                                                       QUERY PLAN                                                                                                                                                                                                       
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                                          QUERY PLAN                                                                                                                                                                                                                          
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
    ->  LockRows
@@ -1603,7 +1603,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
          ->  Foreign Scan
                Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
-               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1
+               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1
                ->  Merge Join
                      Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                      Merge Cond: (t1.c1 = t2.c1)
@@ -1638,8 +1638,8 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
 
 EXPLAIN (COSTS false, VERBOSE)
 SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10 FOR SHARE;
-                                                                                                                                                                                                               QUERY PLAN                                                                                                                                                                                                               
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                                                  QUERY PLAN                                                                                                                                                                                                                                  
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
    ->  LockRows
@@ -1647,7 +1647,7 @@ SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
          ->  Foreign Scan
                Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
-               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1 FOR SHARE OF r2
+               Remote SQL: SELECT r1."C 1", r1.c3, CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r2."C 1", CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST FOR SHARE OF r1 FOR SHARE OF r2
                ->  Merge Join
                      Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                      Merge Cond: (t1.c1 = t2.c1)
@@ -1717,14 +1717,14 @@ WITH t (c1_1, c1_3, c2_1) AS (SELECT t1.c1, t1.c3, t2.c1 FROM ft1 t1 JOIN ft2 t2
 -- ctid with whole-row reference
 EXPLAIN (COSTS false, VERBOSE)
 SELECT t1.ctid, t1, t2, t1.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-                                                                                                                                                                                           QUERY PLAN                                                                                                                                                                                            
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                              QUERY PLAN                                                                                                                                                                                                               
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Limit
    Output: t1.ctid, t1.*, t2.*, t1.c1, t1.c3
    ->  Foreign Scan
          Output: t1.ctid, t1.*, t2.*, t1.c1, t1.c3
          Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
-         Remote SQL: SELECT r1.ctid, CASE WHEN r1.* IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r1."C 1", r1.c3, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
+         Remote SQL: SELECT r1.ctid, CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c7, r1.c8) END, r1."C 1", r1.c3, CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1")))) ORDER BY r1.c3 ASC NULLS LAST, r1."C 1" ASC NULLS LAST
 (6 rows)
 
 -- SEMI JOIN, not pushed down
@@ -2263,6 +2263,26 @@ SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT
 -- recreate the dropped user mapping for further tests
 CREATE USER MAPPING FOR CURRENT_USER SERVER loopback;
 DROP USER MAPPING FOR PUBLIC SERVER loopback;
+-- join with nullable side with some columns with null values
+UPDATE ft5 SET c3 = null where c1 % 9 = 0;
+EXPLAIN VERBOSE SELECT ft5, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2 FROM ft5 left join ft4 on ft5.c1 = ft4.c1 WHERE ft4.c1 BETWEEN 10 and 30 ORDER BY ft5.c1, ft4.c1;
+                                                                                                                                      QUERY PLAN                                                                                                                                      
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan  (cost=100.00..106.81 rows=7 width=62)
+   Output: ft5.*, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2
+   Relations: (public.ft5) INNER JOIN (public.ft4)
+   Remote SQL: SELECT CASE WHEN (r1.*)::pg_catalog.text IS NOT NULL THEN ROW(r1.c1, r1.c2, r1.c3) END, r1.c1, r1.c2, r1.c3, r2.c1, r2.c2 FROM ("S 1"."T 4" r1 INNER JOIN "S 1"."T 3" r2 ON (((r1.c1 = r2.c1)) AND ((r2.c1 >= 10)) AND ((r2.c1 <= 30)))) ORDER BY r1.c1 ASC NULLS LAST
+(4 rows)
+
+SELECT ft5, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2 FROM ft5 left join ft4 on ft5.c1 = ft4.c1 WHERE ft4.c1 BETWEEN 10 and 30 ORDER BY ft5.c1, ft4.c1;
+      ft5       | c1 | c2 |   c3   | c1 | c2 
+----------------+----+----+--------+----+----
+ (12,13,AAA012) | 12 | 13 | AAA012 | 12 | 13
+ (18,19,)       | 18 | 19 |        | 18 | 19
+ (24,25,AAA024) | 24 | 25 | AAA024 | 24 | 25
+ (30,31,AAA030) | 30 | 31 | AAA030 | 30 | 31
+(4 rows)
+
 -- ===================================================================
 -- parameterized queries
 -- ===================================================================
@@ -2880,14 +2900,14 @@ UPDATE ft2 SET c2 = c2 + 400, c3 = c3 || '_update7' WHERE c1 % 10 = 7 RETURNING
 EXPLAIN (verbose, costs off)
 UPDATE ft2 SET c2 = ft2.c2 + 500, c3 = ft2.c3 || '_update9', c7 = DEFAULT
   FROM ft1 WHERE ft1.c1 = ft2.c2 AND ft1.c1 % 10 = 9;                               -- can't be pushed down
-                                                                                                                                                    QUERY PLAN                                                                                                                                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                              QUERY PLAN                                                                                                                                                              
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Update on public.ft2
    Remote SQL: UPDATE "S 1"."T 1" SET c2 = $2, c3 = $3, c7 = $4 WHERE ctid = $1
    ->  Foreign Scan
          Output: ft2.c1, (ft2.c2 + 500), NULL::integer, (ft2.c3 || '_update9'::text), ft2.c4, ft2.c5, ft2.c6, 'ft2       '::character(10), ft2.c8, ft2.ctid, ft1.*
          Relations: (public.ft2) INNER JOIN (public.ft1)
-         Remote SQL: SELECT r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c8, r1.ctid, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 9)))) FOR UPDATE OF r1
+         Remote SQL: SELECT r1."C 1", r1.c2, r1.c3, r1.c4, r1.c5, r1.c6, r1.c8, r1.ctid, CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 9)))) FOR UPDATE OF r1
          ->  Hash Join
                Output: ft2.c1, ft2.c2, ft2.c3, ft2.c4, ft2.c5, ft2.c6, ft2.c8, ft2.ctid, ft1.*
                Hash Cond: (ft2.c2 = ft1.c1)
@@ -3023,14 +3043,14 @@ DELETE FROM ft2 WHERE c1 % 10 = 5 RETURNING c1, c4;
 
 EXPLAIN (verbose, costs off)
 DELETE FROM ft2 USING ft1 WHERE ft1.c1 = ft2.c2 AND ft1.c1 % 10 = 2;                -- can't be pushed down
-                                                                                                                          QUERY PLAN                                                                                                                           
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                    QUERY PLAN                                                                                                                                    
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Delete on public.ft2
    Remote SQL: DELETE FROM "S 1"."T 1" WHERE ctid = $1
    ->  Foreign Scan
          Output: ft2.ctid, ft1.*
          Relations: (public.ft2) INNER JOIN (public.ft1)
-         Remote SQL: SELECT r1.ctid, CASE WHEN r2.* IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 2)))) FOR UPDATE OF r1
+         Remote SQL: SELECT r1.ctid, CASE WHEN (r2.*)::pg_catalog.text IS NOT NULL THEN ROW(r2."C 1", r2.c2, r2.c3, r2.c4, r2.c5, r2.c6, r2.c7, r2.c8) END FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1.c2 = r2."C 1")) AND (((r2."C 1" % 10) = 2)))) FOR UPDATE OF r1
          ->  Hash Join
                Output: ft2.ctid, ft1.*
                Hash Cond: (ft2.c2 = ft1.c1)
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index a2b03a1a71..df4060d57d 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -543,6 +543,11 @@ SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT
 CREATE USER MAPPING FOR CURRENT_USER SERVER loopback;
 DROP USER MAPPING FOR PUBLIC SERVER loopback;
 
+-- join with nullable side with some columns with null values
+UPDATE ft5 SET c3 = null where c1 % 9 = 0;
+EXPLAIN VERBOSE SELECT ft5, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2 FROM ft5 left join ft4 on ft5.c1 = ft4.c1 WHERE ft4.c1 BETWEEN 10 and 30 ORDER BY ft5.c1, ft4.c1;
+SELECT ft5, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2 FROM ft5 left join ft4 on ft5.c1 = ft4.c1 WHERE ft4.c1 BETWEEN 10 and 30 ORDER BY ft5.c1, ft4.c1;
+
 -- ===================================================================
 -- parameterized queries
 -- ===================================================================