On 2016/10/27 20:41, Etsuro Fujita wrote:
Here is the updated version, which includes the restructuring you
proposed.  Other than the above issue and the alias issue we discussed,
I addressed all your comments except one on testing; I tried to add test
cases where the remote query is deparsed as nested subqueries, but I
couldn't because IIUC, reduce_outer_joins reduced full joins to inner
joins or left joins.  So, I added two test cases: (1) the joining
relations are both base relations (actually, we already have that) and
(2) one of the joining relations is a base relation and the other is a
join relation.  I rebased the patch to HEAD, so I added a test case with
aggregate pushdown also.


I've updated another patch for evaluating PHVs remotely. Attached is an updated version of the patch, which is created on top of the patch for supporting deparsing subqueries. You can find test cases where a remote join query is deparsed as nested subqueries.

Best regards,
Etsuro Fujita
*** a/contrib/postgres_fdw/deparse.c
--- b/contrib/postgres_fdw/deparse.c
***************
*** 49,54 ****
--- 49,55 ----
  #include "nodes/nodeFuncs.h"
  #include "nodes/plannodes.h"
  #include "optimizer/clauses.h"
+ #include "optimizer/placeholder.h"
  #include "optimizer/prep.h"
  #include "optimizer/tlist.h"
  #include "optimizer/var.h"
***************
*** 157,162 **** static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context);
--- 158,164 ----
  static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context);
  static void deparseNullTest(NullTest *node, deparse_expr_cxt *context);
  static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context);
+ static void deparseExprInPlaceHolderVar(PlaceHolderVar *node, deparse_expr_cxt *context);
  static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
  				 deparse_expr_cxt *context);
  static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
***************
*** 169,177 **** static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
  static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
  				   bool make_subquery, List **params_list);
  static void appendSubselectAlias(StringInfo buf, int tabno, int ncols);
! static void getSubselectAliasInfo(Var *node, RelOptInfo *foreignrel,
  					  int *tabno, int *colno);
! static bool isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno);
  static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
  static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
  static void appendAggOrderBy(List *orderList, List *targetList,
--- 171,180 ----
  static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
  				   bool make_subquery, List **params_list);
  static void appendSubselectAlias(StringInfo buf, int tabno, int ncols);
! static void getSubselectAliasInfo(Expr *node, RelOptInfo *foreignrel,
  					  int *tabno, int *colno);
! static bool isSubqueryExpr(Expr *node, PlannerInfo *root, RelOptInfo *foreignrel,
! 			   int *tabno, int *colno);
  static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
  static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
  static void appendAggOrderBy(List *orderList, List *targetList,
***************
*** 762,767 **** foreign_expr_walker(Node *node,
--- 765,789 ----
  					state = FDW_COLLATE_UNSAFE;
  			}
  			break;
+ 		case T_PlaceHolderVar:
+ 			{
+ 				PlaceHolderVar *phv = (PlaceHolderVar *) node;
+ 				PlaceHolderInfo *phinfo = find_placeholder_info(glob_cxt->root,
+ 																phv, false);
+ 
+ 				/*
+ 				 * If the PHV's contained expression is computable on the
+ 				 * remote server, we consider the PHV safe to send.
+ 				 */
+ 				if (phv->phlevelsup == 0 &&
+ 					bms_is_subset(phinfo->ph_eval_at,
+ 								  glob_cxt->foreignrel->relids))
+ 					return foreign_expr_walker((Node *) phv->phexpr,
+ 											   glob_cxt, outer_cxt);
+ 				else
+ 					return false;
+ 			}
+ 			break;
  		default:
  
  			/*
***************
*** 856,862 **** deparse_type_name(Oid type_oid, int32 typemod)
   * foreign server.
   */
  List *
! build_tlist_to_deparse(RelOptInfo *foreignrel)
  {
  	List	   *tlist = NIL;
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
--- 878,884 ----
   * foreign server.
   */
  List *
! build_tlist_to_deparse(PlannerInfo *root, RelOptInfo *foreignrel)
  {
  	List	   *tlist = NIL;
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
***************
*** 869,883 **** build_tlist_to_deparse(RelOptInfo *foreignrel)
  		return fpinfo->grouped_tlist;
  
  	/*
! 	 * We require columns specified in foreignrel->reltarget->exprs and those
! 	 * required for evaluating the local conditions.
  	 */
! 	tlist = add_to_flat_tlist(tlist,
! 					   pull_var_clause((Node *) foreignrel->reltarget->exprs,
! 									   PVC_RECURSE_PLACEHOLDERS));
! 	tlist = add_to_flat_tlist(tlist,
! 							  pull_var_clause((Node *) fpinfo->local_conds,
! 											  PVC_RECURSE_PLACEHOLDERS));
  
  	return tlist;
  }
--- 891,963 ----
  		return fpinfo->grouped_tlist;
  
  	/*
! 	 * Fetch all expressions in foreignrel's reltarget if the
! 	 * reltarget_is_shippable flag is set TRUE.  Otherwise, fetch shipplable
! 	 * expressions in the reltarget plus expressions required for evaluating
! 	 * non-shippable expressions in the reltarget.
! 	 */
! 	if (fpinfo->reltarget_is_shippable)
! 		tlist = make_tlist_from_pathtarget(foreignrel->reltarget);
! 	else
! 	{
! 		List	   *exprs = NIL;
! 		ListCell   *lc;
! 
! 		/* Note: we have at least one non-shippable PHV in the reltarget. */
! 		foreach(lc, foreignrel->reltarget->exprs)
! 		{
! 			Node	   *node = (Node *) lfirst(lc);
! 
! 			if (IsA(node, Var))
! 				exprs = lappend(exprs, node);
! 			else if (IsA(node, PlaceHolderVar))
! 			{
! 				PlaceHolderVar *phv = (PlaceHolderVar *) node;
! 				PlaceHolderInfo *phinfo = find_placeholder_info(root, phv,
! 																false);
! 
! 				if (bms_is_subset(phinfo->ph_eval_at,
! 								  fpinfo->outerrel->relids) ||
! 					bms_is_subset(phinfo->ph_eval_at,
! 								  fpinfo->innerrel->relids))
! 				{
! 					/*
! 					 * The PHV coming from an either input should be shippable.
! 					 */
! 					exprs = lappend(exprs, node);
! 				}
! 				else
! 				{
! 					/*
! 					 * The PHV might be shippable, but in any case just fetch
! 					 * expressions required for evaluating the PHV.
! 					 */
! 					List	   *exprs2 = pull_var_clause(node,
! 													PVC_INCLUDE_PLACEHOLDERS);
! 					ListCell   *lc2;
! 
! 					foreach(lc2, exprs2)
! 					{
! 						Node	   *node2 = (Node *) lfirst(lc2);
! 
! 						exprs = lappend(exprs, node2);
! 					}
! 				}
! 			}
! 			else
! 				elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
! 		}
! 
! 		tlist = add_to_flat_tlist(tlist, exprs);
! 	}
! 
! 	/*
! 	 * Fetch expressions required for evaluating local conditions, if any.
  	 */
! 	if (fpinfo->local_conds)
! 		tlist = add_to_flat_tlist(tlist,
! 								pull_var_clause((Node *) fpinfo->local_conds,
! 												PVC_INCLUDE_PLACEHOLDERS));
  
  	return tlist;
  }
***************
*** 1417,1423 **** deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
  
  	Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
  		   foreignrel->reloptkind == RELOPT_JOINREL);
! 	Assert(fpinfo->local_conds == NIL);
  
  	if (make_subquery)
  	{
--- 1497,1503 ----
  
  	Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
  		   foreignrel->reloptkind == RELOPT_JOINREL);
! 	Assert(fpinfo->reltarget_is_shippable && fpinfo->local_conds == NIL);
  
  	if (make_subquery)
  	{
***************
*** 1472,1478 **** appendSubselectAlias(StringInfo buf, int tabno, int ncols)
   * respectively.
   */
  static void
! getSubselectAliasInfo(Var *node, RelOptInfo *foreignrel,
  					  int *tabno, int *colno)
  {
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
--- 1552,1558 ----
   * respectively.
   */
  static void
! getSubselectAliasInfo(Expr *node, RelOptInfo *foreignrel,
  					  int *tabno, int *colno)
  {
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
***************
*** 1505,1515 **** getSubselectAliasInfo(Var *node, RelOptInfo *foreignrel,
   * respectively, in that case.
   */
  static bool
! isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno)
  {
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
  	RelOptInfo *outerrel = fpinfo->outerrel;
  	RelOptInfo *innerrel = fpinfo->innerrel;
  
  	if (foreignrel->reloptkind != RELOPT_JOINREL)
  		return false;
--- 1585,1597 ----
   * respectively, in that case.
   */
  static bool
! isSubqueryExpr(Expr *node, PlannerInfo *root, RelOptInfo *foreignrel,
! 			   int *tabno, int *colno)
  {
  	PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
  	RelOptInfo *outerrel = fpinfo->outerrel;
  	RelOptInfo *innerrel = fpinfo->innerrel;
+ 	bool		is_outer_var;
  
  	if (foreignrel->reloptkind != RELOPT_JOINREL)
  		return false;
***************
*** 1517,1523 **** isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno)
  	if (!fpinfo->subquery_rels)
  		return false;
  
! 	if (bms_is_member(node->varno, outerrel->relids))
  	{
  		/*
  		 * If outer relation is deparsed as a subqeury, the given expression
--- 1599,1630 ----
  	if (!fpinfo->subquery_rels)
  		return false;
  
! 	if (IsA(node, Var))
! 	{
! 		Var		   *var = (Var *) node;
! 
! 		is_outer_var = bms_is_member(var->varno, outerrel->relids);
! 	}
! 	else if (IsA(node, PlaceHolderVar))
! 	{
! 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
! 		PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, false);
! 		bool		is_inner_var;
! 
! 		is_outer_var = bms_is_subset(phinfo->ph_eval_at, outerrel->relids);
! 		is_inner_var = bms_is_subset(phinfo->ph_eval_at, innerrel->relids);
! 
! 		/*
! 		 * If the PHV can't be computed in either input, it will be computed
! 		 * in the current join level; it's not a subquery output column.
! 		 */
! 		if (!is_outer_var && !is_inner_var)
! 			return false;
! 	}
! 	else
! 		elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
! 
! 	if (is_outer_var)
  	{
  		/*
  		 * If outer relation is deparsed as a subqeury, the given expression
***************
*** 1530,1542 **** isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno)
  			return true;
  		}
  		/* Otherwise, recurse into outer relation */
! 		if (isSubqueryExpr(node, outerrel, tabno, colno))
  			return true;
  	}
  	else
  	{
- 		Assert(bms_is_member(node->varno, innerrel->relids));
- 
  		/*
  		 * Likewise for inner relation
  		 */
--- 1637,1647 ----
  			return true;
  		}
  		/* Otherwise, recurse into outer relation */
! 		if (isSubqueryExpr(node, root, outerrel, tabno, colno))
  			return true;
  	}
  	else
  	{
  		/*
  		 * Likewise for inner relation
  		 */
***************
*** 1545,1551 **** isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno)
  			getSubselectAliasInfo(node, innerrel, tabno, colno);
  			return true;
  		}
! 		if (isSubqueryExpr(node, innerrel, tabno, colno))
  			return true;
  	}
  	return false;
--- 1650,1656 ----
  			getSubselectAliasInfo(node, innerrel, tabno, colno);
  			return true;
  		}
! 		if (isSubqueryExpr(node, root, innerrel, tabno, colno))
  			return true;
  	}
  	return false;
***************
*** 1932,1940 **** deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
  	{
  		/*
  		 * All other system attributes are fetched as 0, except for table OID,
! 		 * which is fetched as the local table OID.  However, we must be
! 		 * careful; the table could be beneath an outer join, in which case it
! 		 * must go to NULL whenever the rest of the row does.
  		 */
  		Oid			fetchval = 0;
  
--- 2037,2043 ----
  	{
  		/*
  		 * All other system attributes are fetched as 0, except for table OID,
! 		 * which is fetched as the local table OID.
  		 */
  		Oid			fetchval = 0;
  
***************
*** 1944,1957 **** deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
  			fetchval = rte->relid;
  		}
  
! 		if (qualify_col)
! 		{
! 			appendStringInfoString(buf, "CASE WHEN (");
! 			ADD_REL_QUALIFIER(buf, varno);
! 			appendStringInfo(buf, "*)::text IS NOT NULL THEN %u END", fetchval);
! 		}
! 		else
! 			appendStringInfo(buf, "%u", fetchval);
  	}
  	else if (varattno == 0)
  	{
--- 2047,2053 ----
  			fetchval = rte->relid;
  		}
  
! 		appendStringInfo(buf, "%u", fetchval);
  	}
  	else if (varattno == 0)
  	{
***************
*** 1982,2009 **** deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
  		attrs_used = bms_add_member(NULL,
  									0 - FirstLowInvalidHeapAttributeNumber);
  
- 		/*
- 		 * In case the whole-row reference is under an outer join then it has
- 		 * to go NULL whenever the rest of the row goes NULL. Deparsing a join
- 		 * query would always involve multiple relations, thus qualify_col
- 		 * would be true.
- 		 */
- 		if (qualify_col)
- 		{
- 			appendStringInfoString(buf, "CASE WHEN (");
- 			ADD_REL_QUALIFIER(buf, varno);
- 			appendStringInfo(buf, "*)::text IS NOT NULL THEN ");
- 		}
- 
  		appendStringInfoString(buf, "ROW(");
  		deparseTargetList(buf, root, varno, rel, false, attrs_used, qualify_col,
  						  &retrieved_attrs);
  		appendStringInfoString(buf, ")");
  
- 		/* Complete the CASE WHEN statement started above. */
- 		if (qualify_col)
- 			appendStringInfo(buf, " END");
- 
  		heap_close(rel, NoLock);
  		bms_free(attrs_used);
  	}
--- 2078,2088 ----
***************
*** 2176,2181 **** deparseExpr(Expr *node, deparse_expr_cxt *context)
--- 2255,2263 ----
  		case T_Aggref:
  			deparseAggref((Aggref *) node, context);
  			break;
+ 		case T_PlaceHolderVar:
+ 			deparseExprInPlaceHolderVar((PlaceHolderVar *) node, context);
+ 			break;
  		default:
  			elog(ERROR, "unsupported expression type for deparse: %d",
  				 (int) nodeTag(node));
***************
*** 2195,2200 **** static void
--- 2277,2283 ----
  deparseVar(Var *node, deparse_expr_cxt *context)
  {
  	Relids		relids = context->scanrel->relids;
+ 	PlannerInfo *root = context->root;
  	RelOptInfo *rel = (context->foreignrel->reloptkind == RELOPT_UPPER_REL) ?
  		context->scanrel : context->foreignrel;
  	int			tabno;
***************
*** 2207,2213 **** deparseVar(Var *node, deparse_expr_cxt *context)
  	 * If the given Var is an output column of a subquery-in-FROM, deparse
  	 * the alias to the given Var instead.
  	 */
! 	if (isSubqueryExpr(node, rel, &tabno, &colno))
  	{
  		appendStringInfo(context->buf, "%s%d.%s%d",
  						 SS_TAB_ALIAS_PREFIX, tabno,
--- 2290,2296 ----
  	 * If the given Var is an output column of a subquery-in-FROM, deparse
  	 * the alias to the given Var instead.
  	 */
! 	if (isSubqueryExpr((Expr *) node, root, rel, &tabno, &colno))
  	{
  		appendStringInfo(context->buf, "%s%d.%s%d",
  						 SS_TAB_ALIAS_PREFIX, tabno,
***************
*** 2901,2906 **** appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context)
--- 2984,3016 ----
  }
  
  /*
+  * Deparse a PlaceHolderVar's contained expression.
+  */
+ static void
+ deparseExprInPlaceHolderVar(PlaceHolderVar *node, deparse_expr_cxt *context)
+ {
+ 	PlannerInfo *root = context->root;
+ 	RelOptInfo *rel = (context->foreignrel->reloptkind == RELOPT_UPPER_REL) ?
+ 		context->scanrel : context->foreignrel;
+ 	int			tabno;
+ 	int			colno;
+ 
+ 	/*
+ 	 * If the given PHV is an output column of a subquery-in-FROM, deparse
+ 	 * the alias to the given PHV instead.
+ 	 */
+ 	if (isSubqueryExpr((Expr *) node, root, rel, &tabno, &colno))
+ 	{
+ 		appendStringInfo(context->buf, "%s%d.%s%d",
+ 						 SS_TAB_ALIAS_PREFIX, tabno,
+ 						 SS_COL_ALIAS_PREFIX, colno);
+ 		return;
+ 	}
+ 
+ 	deparseExpr(node->phexpr, context);
+ }
+ 
+ /*
   * Print the representation of a parameter to be sent to the remote side.
   *
   * Note: we always label the Param's type explicitly rather than relying on
*** a/contrib/postgres_fdw/expected/postgres_fdw.out
--- b/contrib/postgres_fdw/expected/postgres_fdw.out
***************
*** 1267,1280 **** SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1
  -- full outer join + inner join
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT t1, t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
!                                                                                                                                                                               QUERY PLAN                                                                                                                                                                               
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.*, t1.c1, t2.c1, t3.c1
     ->  Foreign Scan
           Output: t1.*, t1.c1, t2.c1, t3.c1
           Relations: ((public.ft4 t1) INNER JOIN (public.ft5 t2)) FULL JOIN (public.ft4 t3)
!          Remote SQL: SELECT CASE WHEN (r1.*)::text IS NOT NULL THEN ROW(r1.c1, r1.c2, r1.c3) END, r1.c1, r2.c1, r4.c1 FROM (("S 1"."T 3" r1 INNER JOIN "S 1"."T 4" r2 ON (((r1.c1 = (r2.c1 + 1))) AND ((r1.c1 >= 50)) AND ((r1.c1 <= 60)))) FULL JOIN "S 1"."T 3" r4 ON (((r2.c1 = r4.c1)))) ORDER BY r1.c1 ASC NULLS LAST, r2.c1 ASC NULLS LAST, r4.c1 ASC NULLS LAST
  (6 rows)
  
  SELECT t1, t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
--- 1267,1280 ----
  -- full outer join + inner join
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT t1, t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
!                                                                                                                                                                   QUERY PLAN                                                                                                                                                                  
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.*, t1.c1, t2.c1, t3.c1
     ->  Foreign Scan
           Output: t1.*, t1.c1, t2.c1, t3.c1
           Relations: ((public.ft4 t1) INNER JOIN (public.ft5 t2)) FULL JOIN (public.ft4 t3)
!          Remote SQL: SELECT s1.c1, s1.c2, r2.c1, r4.c1 FROM (((SELECT ROW(c1, c2, c3), c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s1(c1, c2) INNER JOIN "S 1"."T 4" r2 ON (((s1.c2 = (r2.c1 + 1))))) FULL JOIN "S 1"."T 3" r4 ON (((r2.c1 = r4.c1)))) ORDER BY s1.c2 ASC NULLS LAST, r2.c1 ASC NULLS LAST, r4.c1 ASC NULLS LAST
  (6 rows)
  
  SELECT t1, t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
***************
*** 1523,1530 **** 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 (VERBOSE, COSTS OFF)
  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                                                                                                                                                                                                                
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
--- 1523,1530 ----
  -- tests whole-row reference for row marks
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                        
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
***************
*** 1532,1538 **** 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.*)::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.*)::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)
--- 1532,1538 ----
           ->  Foreign Scan
                 Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                 Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
!                Remote SQL: SELECT s1.c1, s1.c2, s1.c3, s2.c1, s2.c2 FROM ((SELECT "C 1", c3, ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR UPDATE) s1(c1, c2, c3) INNER JOIN (SELECT "C 1", ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1") s2(c1, c2) ON (((s1.c1 = s2.c1)))) ORDER BY s1.c2 ASC NULLS LAST, s1.c1 ASC NULLS LAST
                 ->  Merge Join
                       Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                       Merge Cond: (t1.c1 = t2.c1)
***************
*** 1567,1574 **** SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
  
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                                                                        
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
--- 1567,1574 ----
  
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                              
! ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
***************
*** 1576,1582 **** 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.*)::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.*)::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)
--- 1576,1582 ----
           ->  Foreign Scan
                 Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                 Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
!                Remote SQL: SELECT s1.c1, s1.c2, s1.c3, s2.c1, s2.c2 FROM ((SELECT "C 1", c3, ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR UPDATE) s1(c1, c2, c3) INNER JOIN (SELECT "C 1", ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR UPDATE) s2(c1, c2) ON (((s1.c1 = s2.c1)))) ORDER BY s1.c2 ASC NULLS LAST, s1.c1 ASC NULLS LAST
                 ->  Merge Join
                       Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                       Merge Cond: (t1.c1 = t2.c1)
***************
*** 1612,1619 **** 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 (VERBOSE, COSTS OFF)
  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                                                                                                                                                                                                               
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
--- 1612,1619 ----
  -- join two tables with FOR SHARE clause
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                        
! ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
***************
*** 1621,1627 **** 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.*)::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.*)::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)
--- 1621,1627 ----
           ->  Foreign Scan
                 Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                 Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
!                Remote SQL: SELECT s1.c1, s1.c2, s1.c3, s2.c1, s2.c2 FROM ((SELECT "C 1", c3, ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR SHARE) s1(c1, c2, c3) INNER JOIN (SELECT "C 1", ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1") s2(c1, c2) ON (((s1.c1 = s2.c1)))) ORDER BY s1.c2 ASC NULLS LAST, s1.c1 ASC NULLS LAST
                 ->  Merge Join
                       Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                       Merge Cond: (t1.c1 = t2.c1)
***************
*** 1656,1663 **** SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t
  
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                                                                       
! --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
--- 1656,1663 ----
  
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                             
! -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   Limit
     Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
     ->  LockRows
***************
*** 1665,1671 **** 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.*)::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.*)::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)
--- 1665,1671 ----
           ->  Foreign Scan
                 Output: t1.c1, t2.c1, t1.c3, t1.*, t2.*
                 Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
!                Remote SQL: SELECT s1.c1, s1.c2, s1.c3, s2.c1, s2.c2 FROM ((SELECT "C 1", c3, ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR SHARE) s1(c1, c2, c3) INNER JOIN (SELECT "C 1", ROW("C 1", c2, c3, c4, c5, c6, c7, c8) FROM "S 1"."T 1" FOR SHARE) s2(c1, c2) ON (((s1.c1 = s2.c1)))) ORDER BY s1.c2 ASC NULLS LAST, s1.c1 ASC NULLS LAST
                 ->  Merge Join
                       Output: t1.c1, t1.c3, t1.*, t2.c1, t2.*
                       Merge Cond: (t1.c1 = t2.c1)
***************
*** 1735,1748 **** 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 (VERBOSE, COSTS OFF)
  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                                                                                                                                                                                                    
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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.*)::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.*)::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
--- 1735,1748 ----
  -- ctid with whole-row reference
  EXPLAIN (VERBOSE, COSTS OFF)
  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                                                                                                                                                                     
! ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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 s1.c1, s1.c2, s1.c3, s1.c4, s2.c1 FROM ((SELECT ctid, ROW("C 1", c2, c3, c4, c5, c6, c7, c8), "C 1", c3 FROM "S 1"."T 1") s1(c1, c2, c3, c4) INNER JOIN (SELECT ROW("C 1", c2, c3, c4, c5, c6, c7, c8), "C 1" FROM "S 1"."T 1") s2(c1, c2) ON (((s1.c3 = s2.c2)))) ORDER BY s1.c4 ASC NULLS LAST, s1.c3 ASC NULLS LAST
  (6 rows)
  
  -- SEMI JOIN, not pushed down
***************
*** 2071,2095 **** SELECT t1."C 1" FROM "S 1"."T 1" t1, LATERAL (SELECT DISTINCT t2.c1, t3.c1 FROM
     1
  (10 rows)
  
! -- non-Var items in targelist of the nullable rel of a join preventing
! -- push-down in some cases
! -- unable to push {ft1, ft2}
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
!                                                         QUERY PLAN                                                         
! ---------------------------------------------------------------------------------------------------------------------------
!  Nested Loop Left Join
     Output: (13), ft2.c1
!    Join Filter: (13 = ft2.c1)
!    ->  Foreign Scan on public.ft2
!          Output: ft2.c1
!          Remote SQL: SELECT "C 1" FROM "S 1"."T 1" WHERE (("C 1" >= 10)) AND (("C 1" <= 15)) ORDER BY "C 1" ASC NULLS LAST
!    ->  Materialize
!          Output: (13)
!          ->  Foreign Scan on public.ft1
!                Output: 13
!                Remote SQL: SELECT NULL FROM "S 1"."T 1" WHERE (("C 1" = 13))
! (11 rows)
  
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
   a  | c1 
--- 2071,2086 ----
     1
  (10 rows)
  
! -- check join pushdown in situations where PHVs are involved
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
!                                                                                               QUERY PLAN                                                                                              
! ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
!  Foreign Scan
     Output: (13), ft2.c1
!    Relations: (public.ft2) LEFT JOIN (public.ft1)
!    Remote SQL: SELECT r2."C 1", s4.c1 FROM ("S 1"."T 1" r2 LEFT JOIN (SELECT 13 FROM "S 1"."T 1" WHERE (("C 1" = 13))) s4(c1) ON (((13 = r2."C 1")))) WHERE ((r2."C 1" >= 10)) AND ((r2."C 1" <= 15))
! (4 rows)
  
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
   a  | c1 
***************
*** 2102,2125 **** SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 O
      | 15
  (6 rows)
  
- -- ok to push {ft1, ft2} but not {ft1, ft2, ft4}
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
!                                                                                     QUERY PLAN                                                                                     
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
!  Nested Loop Left Join
     Output: ft4.c1, (13), ft1.c1, ft2.c1
!    Join Filter: (ft4.c1 = ft1.c1)
!    ->  Foreign Scan on public.ft4
!          Output: ft4.c1, ft4.c2, ft4.c3
!          Remote SQL: SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 10)) AND ((c1 <= 15))
!    ->  Materialize
!          Output: ft1.c1, ft2.c1, (13)
!          ->  Foreign Scan
!                Output: ft1.c1, ft2.c1, 13
!                Relations: (public.ft1) INNER JOIN (public.ft2)
!                Remote SQL: SELECT r4."C 1", r5."C 1" FROM ("S 1"."T 1" r4 INNER JOIN "S 1"."T 1" r5 ON (((r5."C 1" = 12)) AND ((r4."C 1" = 12)))) ORDER BY r4."C 1" ASC NULLS LAST
! (12 rows)
  
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
   c1 | a  | b  | c  
--- 2093,2107 ----
      | 15
  (6 rows)
  
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
!                                                                                                                                           QUERY PLAN                                                                                                                                          
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
!  Foreign Scan
     Output: ft4.c1, (13), ft1.c1, ft2.c1
!    Relations: (public.ft4) LEFT JOIN ((public.ft1) INNER JOIN (public.ft2))
!    Remote SQL: SELECT r1.c1, s7.c1, s7.c2, s7.c3 FROM ("S 1"."T 3" r1 LEFT JOIN (SELECT r4."C 1", r5."C 1", 13 FROM ("S 1"."T 1" r4 INNER JOIN "S 1"."T 1" r5 ON (((r5."C 1" = 12)) AND ((r4."C 1" = 12))))) s7(c1, c2, c3) ON (((r1.c1 = s7.c1)))) WHERE ((r1.c1 >= 10)) AND ((r1.c1 <= 15))
! (4 rows)
  
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
   c1 | a  | b  | c  
***************
*** 2129,2144 **** SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT
   14 |    |    |   
  (3 rows)
  
  -- join with nullable side with some columns with null values
  UPDATE ft5 SET c3 = null where c1 % 9 = 0;
  EXPLAIN (VERBOSE, COSTS OFF)
  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
     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.*)::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;
--- 2111,2170 ----
   14 |    |    |   
  (3 rows)
  
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT ft2.c1, q2.* FROM ft2 LEFT JOIN (SELECT 13, q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15) q2(a2, b2, c2) ON (ft2.c1 = q2.a2) WHERE ft2.c1 BETWEEN 10 AND 15;
+                                                                                                                                                                               QUERY PLAN                                                                                                                                                                               
+ -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+  Foreign Scan
+    Output: ft2.c1, (13), (13), ft2_1.c1
+    Relations: (public.ft2) LEFT JOIN ((public.ft2) LEFT JOIN (public.ft1))
+    Remote SQL: SELECT r1."C 1", s8.c1, s8.c2, s8.c3 FROM ("S 1"."T 1" r1 LEFT JOIN (SELECT r5."C 1", 13, s7.c1 FROM ("S 1"."T 1" r5 LEFT JOIN (SELECT 13 FROM "S 1"."T 1" WHERE (("C 1" = 13))) s7(c1) ON (((13 = r5."C 1")))) WHERE ((r5."C 1" >= 10)) AND ((r5."C 1" <= 15))) s8(c1, c2, c3) ON (((r1."C 1" = 13)))) WHERE ((r1."C 1" >= 10)) AND ((r1."C 1" <= 15))
+ (4 rows)
+ 
+ SELECT ft2.c1, q2.* FROM ft2 LEFT JOIN (SELECT 13, q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15) q2(a2, b2, c2) ON (ft2.c1 = q2.a2) WHERE ft2.c1 BETWEEN 10 AND 15;
+  c1 | a2 | b2 | c2 
+ ----+----+----+----
+  10 |    |    |   
+  11 |    |    |   
+  12 |    |    |   
+  13 | 13 |    | 10
+  13 | 13 |    | 11
+  13 | 13 |    | 12
+  13 | 13 | 13 | 13
+  13 | 13 |    | 14
+  13 | 13 |    | 15
+  14 |    |    |   
+  15 |    |    |   
+ (11 rows)
+ 
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT ft4.c1, q2.* FROM ft4 LEFT JOIN (SELECT (q.a IS NOT NULL), ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15) q2(a2, b2, c2, d2, e2) ON (ft4.c1 = q2.b2) WHERE ft4.c1 BETWEEN 10 AND 15;
+                                                                                                                                                                                                                                                 QUERY PLAN                                                                                                                                                                                                                                                
+ ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+  Foreign Scan
+    Output: ft4.c1, ((13 IS NOT NULL)), ft4_1.c1, (13), ft1.c1, ft2.c1
+    Relations: (public.ft4) LEFT JOIN ((public.ft4) LEFT JOIN ((public.ft1) INNER JOIN (public.ft2)))
+    Remote SQL: SELECT r1.c1, s11.c1, s11.c2, s11.c3, s11.c4, s11.c5 FROM ("S 1"."T 3" r1 LEFT JOIN (SELECT r4.c1, s10.c1, s10.c2, (s10.c3 IS NOT NULL), s10.c3 FROM ("S 1"."T 3" r4 LEFT JOIN (SELECT r7."C 1", r8."C 1", 13 FROM ("S 1"."T 1" r7 INNER JOIN "S 1"."T 1" r8 ON (((r8."C 1" = 12)) AND ((r7."C 1" = 12))))) s10(c1, c2, c3) ON (((r4.c1 = s10.c1)))) WHERE ((r4.c1 >= 10)) AND ((r4.c1 <= 15))) s11(c1, c2, c3, c4, c5) ON (((r1.c1 = s11.c1)))) WHERE ((r1.c1 >= 10)) AND ((r1.c1 <= 15))
+ (4 rows)
+ 
+ SELECT ft4.c1, q2.* FROM ft4 LEFT JOIN (SELECT (q.a IS NOT NULL), ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15) q2(a2, b2, c2, d2, e2) ON (ft4.c1 = q2.b2) WHERE ft4.c1 BETWEEN 10 AND 15;
+  c1 | a2 | b2 | c2 | d2 | e2 
+ ----+----+----+----+----+----
+  10 | f  | 10 |    |    |   
+  12 | t  | 12 | 13 | 12 | 12
+  14 | f  | 14 |    |    |   
+ (3 rows)
+ 
  -- join with nullable side with some columns with null values
  UPDATE ft5 SET c3 = null where c1 % 9 = 0;
  EXPLAIN (VERBOSE, COSTS OFF)
  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
     Output: ft5.*, ft5.c1, ft5.c2, ft5.c3, ft4.c1, ft4.c2
     Relations: (public.ft5) INNER JOIN (public.ft4)
!    Remote SQL: SELECT s1.c1, s1.c2, s1.c3, s1.c4, r2.c1, r2.c2 FROM ((SELECT ROW(c1, c2, c3), c1, c2, c3 FROM "S 1"."T 4") s1(c1, c2, c3, c4) INNER JOIN "S 1"."T 3" r2 ON (((s1.c2 = r2.c1)) AND ((r2.c1 >= 10)) AND ((r2.c1 <= 30)))) ORDER BY s1.c2 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;
***************
*** 4040,4053 **** 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                                                                                                                                                         
! ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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.*)::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)
--- 4066,4079 ----
  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                                                                                                                                      
! --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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, s2.c1 FROM ("S 1"."T 1" r1 INNER JOIN (SELECT ROW("C 1", c2, c3, c4, c5, c6, c7, c8), "C 1" FROM "S 1"."T 1" WHERE ((("C 1" % 10) = 9))) s2(c1, c2) ON (((r1.c2 = s2.c2)))) 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)
***************
*** 4183,4196 **** 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                                                                                                                               
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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.*)::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)
--- 4209,4222 ----
  
  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                                                                                                            
! ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   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, s2.c1 FROM ("S 1"."T 1" r1 INNER JOIN (SELECT ROW("C 1", c2, c3, c4, c5, c6, c7, c8), "C 1" FROM "S 1"."T 1" WHERE ((("C 1" % 10) = 2))) s2(c1, c2) ON (((r1.c2 = s2.c2)))) FOR UPDATE OF r1
           ->  Hash Join
                 Output: ft2.ctid, ft1.*
                 Hash Cond: (ft2.c2 = ft1.c1)
*** a/contrib/postgres_fdw/postgres_fdw.c
--- b/contrib/postgres_fdw/postgres_fdw.c
***************
*** 28,33 ****
--- 28,34 ----
  #include "optimizer/clauses.h"
  #include "optimizer/pathnode.h"
  #include "optimizer/paths.h"
+ #include "optimizer/placeholder.h"
  #include "optimizer/planmain.h"
  #include "optimizer/restrictinfo.h"
  #include "optimizer/var.h"
***************
*** 582,587 **** postgresGetForeignRelSize(PlannerInfo *root,
--- 583,630 ----
  	}
  
  	/*
+ 	 * Decide whether expressions in the reltarget are shippable and whether
+ 	 * there are any non-Vars in those expressions.
+ 	 *
+ 	 * Note: if the relation is an appendrel child, it isn't in the main join
+ 	 * tree, so the info is not used.
+ 	 */
+ 	if (baserel->reloptkind == RELOPT_BASEREL)
+ 	{
+ 		bool		reltarget_is_shippable = true;
+ 		bool		reltarget_has_non_vars = false;
+ 
+ 		foreach(lc, baserel->reltarget->exprs)
+ 		{
+ 			Node	   *node = (Node *) lfirst(lc);
+ 
+ 			if (IsA(node, Var))
+ 			{
+ 				Var		   *var = (Var *) node;
+ 
+ 				if (var->varattno <= 0 &&
+ 					var->varattno != SelfItemPointerAttributeNumber &&
+ 					var->varattno != ObjectIdAttributeNumber)
+ 					reltarget_has_non_vars = true;
+ 			}
+ 			else if (IsA(node, PlaceHolderVar))
+ 			{
+ 				reltarget_has_non_vars = true;
+ 
+ 				if (!is_foreign_expr(root, baserel, (Expr *) node))
+ 				{
+ 					reltarget_is_shippable = false;
+ 					break;
+ 				}
+ 			}
+ 			else
+ 				elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
+ 		}
+ 		fpinfo->reltarget_is_shippable = reltarget_is_shippable;
+ 		fpinfo->reltarget_has_non_vars = reltarget_has_non_vars;
+ 	}
+ 
+ 	/*
  	 * Compute the selectivity and cost of the local_conds, so we don't have
  	 * to do it over again for each path.  The best we can do for these
  	 * conditions is to estimate selectivity on the basis of local statistics.
***************
*** 1199,1205 **** postgresGetForeignPlan(PlannerInfo *root,
  		local_exprs = fpinfo->local_conds;
  
  		/* Build the list of columns to be fetched from the foreign server. */
! 		fdw_scan_tlist = build_tlist_to_deparse(foreignrel);
  
  		/*
  		 * Ensure that the outer plan produces a tuple whose descriptor
--- 1242,1248 ----
  		local_exprs = fpinfo->local_conds;
  
  		/* Build the list of columns to be fetched from the foreign server. */
! 		fdw_scan_tlist = build_tlist_to_deparse(root, foreignrel);
  
  		/*
  		 * Ensure that the outer plan produces a tuple whose descriptor
***************
*** 2539,2545 **** estimate_path_cost_size(PlannerInfo *root,
  		/* Build the list of columns to be fetched from the foreign server. */
  		if (foreignrel->reloptkind == RELOPT_JOINREL ||
  			foreignrel->reloptkind == RELOPT_UPPER_REL)
! 			fdw_scan_tlist = build_tlist_to_deparse(foreignrel);
  		else
  			fdw_scan_tlist = NIL;
  
--- 2582,2588 ----
  		/* Build the list of columns to be fetched from the foreign server. */
  		if (foreignrel->reloptkind == RELOPT_JOINREL ||
  			foreignrel->reloptkind == RELOPT_UPPER_REL)
! 			fdw_scan_tlist = build_tlist_to_deparse(root, foreignrel);
  		else
  			fdw_scan_tlist = NIL;
  
***************
*** 4055,4060 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4098,4105 ----
  	ListCell   *lc;
  	List	   *joinclauses;
  	List	   *otherclauses;
+ 	bool		reltarget_is_shippable = true;
+ 	bool		reltarget_has_non_vars = false;
  
  	/*
  	 * We support pushing down INNER, LEFT, RIGHT and FULL OUTER joins.
***************
*** 4084,4089 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4129,4142 ----
  	if (fpinfo_o->local_conds || fpinfo_i->local_conds)
  		return false;
  
+ 	/*
+ 	 * If the reltargets of joining relations are not shippable, those are
+ 	 * required to be evaluated locally, so the join can not be pushed down.
+ 	 */
+ 	if (!fpinfo_o->reltarget_is_shippable ||
+ 		!fpinfo_i->reltarget_is_shippable)
+ 		return false;
+ 
  	/* Separate restrict list into join quals and quals on join relation */
  	if (IS_OUTER_JOIN(jointype))
  		extract_actual_join_clauses(extra->restrictlist, &joinclauses, &otherclauses);
***************
*** 4109,4134 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
  			return false;
  	}
  
- 	/*
- 	 * deparseExplicitTargetList() isn't smart enough to handle anything other
- 	 * than a Var.  In particular, if there's some PlaceHolderVar that would
- 	 * need to be evaluated within this join tree (because there's an upper
- 	 * reference to a quantity that may go to NULL as a result of an outer
- 	 * join), then we can't try to push the join down because we'll fail when
- 	 * we get to deparseExplicitTargetList().  However, a PlaceHolderVar that
- 	 * needs to be evaluated *at the top* of this join tree is OK, because we
- 	 * can do that locally after fetching the results from the remote side.
- 	 */
- 	foreach(lc, root->placeholder_list)
- 	{
- 		PlaceHolderInfo *phinfo = lfirst(lc);
- 		Relids		relids = joinrel->relids;
- 
- 		if (bms_is_subset(phinfo->ph_eval_at, relids) &&
- 			bms_nonempty_difference(relids, phinfo->ph_eval_at))
- 			return false;
- 	}
- 
  	/* Save the join clauses, for later use. */
  	fpinfo->joinclauses = joinclauses;
  
--- 4162,4167 ----
***************
*** 4185,4211 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
  	 *
  	 * The joining sides can not have local conditions, thus no need to test
  	 * shippability of the clauses being pulled up.
  	 */
  	switch (jointype)
  	{
  		case JOIN_INNER:
! 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_i->remote_conds));
! 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_o->remote_conds));
  			break;
  
  		case JOIN_LEFT:
! 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  										  list_copy(fpinfo_i->remote_conds));
! 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_o->remote_conds));
  			break;
  
  		case JOIN_RIGHT:
! 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  										  list_copy(fpinfo_o->remote_conds));
! 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_i->remote_conds));
  			break;
  
--- 4218,4267 ----
  	 *
  	 * The joining sides can not have local conditions, thus no need to test
  	 * shippability of the clauses being pulled up.
+ 	 *
+ 	 * If the joining relation has reltarget_has_non_vars=TRUE, it's deparsed
+ 	 * as a subquery in which the remote_conds of the relation is transformed
+ 	 * into the subquery's WHERE clause; so in that case, don't pull up the
+ 	 * remote_conds into the joinclauses or remote_conds of this relation.
  	 */
  	switch (jointype)
  	{
  		case JOIN_INNER:
! 			if (fpinfo_i->reltarget_has_non_vars)
! 				fpinfo->make_innerrel_subquery = true;
! 			else
! 				fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_i->remote_conds));
! 			if (fpinfo_o->reltarget_has_non_vars)
! 				fpinfo->make_outerrel_subquery = true;
! 			else
! 				fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_o->remote_conds));
  			break;
  
  		case JOIN_LEFT:
! 			if (fpinfo_i->reltarget_has_non_vars)
! 				fpinfo->make_innerrel_subquery = true;
! 			else
! 				fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  										  list_copy(fpinfo_i->remote_conds));
! 			if (fpinfo_o->reltarget_has_non_vars)
! 				fpinfo->make_outerrel_subquery = true;
! 			else
! 				fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_o->remote_conds));
  			break;
  
  		case JOIN_RIGHT:
! 			if (fpinfo_o->reltarget_has_non_vars)
! 				fpinfo->make_outerrel_subquery = true;
! 			else
! 				fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
  										  list_copy(fpinfo_o->remote_conds));
! 			if (fpinfo_i->reltarget_has_non_vars)
! 				fpinfo->make_innerrel_subquery = true;
! 			else
! 				fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
  										  list_copy(fpinfo_i->remote_conds));
  			break;
  
***************
*** 4215,4236 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
  			 * In this case, if any of the joining relations has conditions,
  			 * we need to deparse that relation as a subquery so that
  			 * conditions can be evaluated before the join.  Remember it in
! 			 * the fpinfo so that deparser can take appropriate action.  We
! 			 * also save the relids of that relation that is covered by the
! 			 * subquery for later use of deparser.
  			 */
! 			if (fpinfo_o->remote_conds)
! 			{
  				fpinfo->make_outerrel_subquery = true;
! 				fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
! 														outerrel->relids);
! 			}
! 			if (fpinfo_i->remote_conds)
! 			{
  				fpinfo->make_innerrel_subquery = true;
- 				fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
- 														innerrel->relids);
- 			}
  			break;
  
  		default:
--- 4271,4282 ----
  			 * In this case, if any of the joining relations has conditions,
  			 * we need to deparse that relation as a subquery so that
  			 * conditions can be evaluated before the join.  Remember it in
! 			 * the fpinfo so that deparser can take appropriate action.
  			 */
! 			if (fpinfo_o->reltarget_has_non_vars || fpinfo_o->remote_conds)
  				fpinfo->make_outerrel_subquery = true;
! 			if (fpinfo_i->reltarget_has_non_vars || fpinfo_i->remote_conds)
  				fpinfo->make_innerrel_subquery = true;
  			break;
  
  		default:
***************
*** 4239,4244 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4285,4301 ----
  	}
  
  	/*
+ 	 * If the joining relation is deparsed as a subquery, save the relids for
+ 	 * later use of deparser.
+ 	 */
+ 	if (fpinfo->make_outerrel_subquery)
+ 		fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
+ 												outerrel->relids);
+ 	if (fpinfo->make_innerrel_subquery)
+ 		fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
+ 												innerrel->relids);
+ 
+ 	/*
  	 * For an inner join, all restrictions can be treated alike. Treating the
  	 * pushed down conditions as join conditions allows a top level full outer
  	 * join to be deparsed without requiring subqueries.
***************
*** 4254,4259 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4311,4354 ----
  	fpinfo->pushdown_safe = true;
  
  	/*
+ 	 * Decide whether expressions in the reltarget are shippable and whether
+ 	 * there are any non-Vars in those expressions.
+ 	 *
+ 	 * Note: we don't need to be careful about whole-row references or system
+ 	 * columns other than ctid and oid here; those would be handled as output
+ 	 * columns of lower subqueries, if any.
+ 	 */
+ 	foreach(lc, joinrel->reltarget->exprs)
+ 	{
+ 		Node	   *node = (Node *) lfirst(lc);
+ 
+ 		if (IsA(node, Var))
+ 			continue;
+ 		if (IsA(node, PlaceHolderVar))
+ 		{
+ 			PlaceHolderVar *phv = (PlaceHolderVar *) node;
+ 			PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, false);
+ 
+ 			/* Ignore the PHV if it has bubbled up from an either input. */
+ 			if (bms_is_subset(phinfo->ph_eval_at, outerrel->relids) ||
+ 				bms_is_subset(phinfo->ph_eval_at, innerrel->relids))
+ 				continue;
+ 
+ 			reltarget_has_non_vars = true;
+ 
+ 			if (!is_foreign_expr(root, joinrel, (Expr *) node))
+ 			{
+ 				reltarget_is_shippable = false;
+ 				break;
+ 			}
+ 		}
+ 		else
+ 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
+ 	}
+ 	fpinfo->reltarget_is_shippable = reltarget_is_shippable;
+ 	fpinfo->reltarget_has_non_vars = reltarget_has_non_vars;
+ 
+ 	/*
  	 * If user is willing to estimate cost for a scan of either of the joining
  	 * relations using EXPLAIN, he intends to estimate scans on that relation
  	 * more accurately. Then, it makes sense to estimate the cost the join
*** a/contrib/postgres_fdw/postgres_fdw.h
--- b/contrib/postgres_fdw/postgres_fdw.h
***************
*** 33,38 **** typedef struct PgFdwRelationInfo
--- 33,61 ----
  	bool		pushdown_safe;
  
  	/*
+ 	 * Flags on the reltarget of the relation.
+ 	 *
+ 	 * If each expression in the relation's reltarget was shippable (i.e.,
+ 	 * computable on the remote side), we set reltarget_is_shippalbe to TRUE.
+ 	 * The flag is used to decide whether the relation can be joined with any
+ 	 * other foreign table or join (see foreign_join_ok).  Note that Vars in
+ 	 * the reltarget are shippable, so if PHVs in the reltarget (if any) were
+ 	 * shippable, the flag is set TRUE.
+ 	 *
+ 	 * If the reltarget contained any PHVs, we need to deparse the relation as
+ 	 * a subquery when creating a remote query; so in that case, we set
+ 	 * reltarget_has_non_vars to TRUE, to let deparse.c know about that.  If
+ 	 * the reltarget of a base relation contained a whole-row reference and/or
+ 	 * system columns other than citd and oid, the flag is also set TRUE; in
+ 	 * that case, the subquery will emit a ROW() expression for a whole-row
+ 	 * reference and 0 for system columns other than ctid and oid, except for
+ 	 * tableoid, in which case, a valid value for the local table OID will be
+ 	 * emitted by the subquery.
+ 	 */
+ 	bool		reltarget_is_shippable; /* are reltarget exprs shippable? */
+ 	bool		reltarget_has_non_vars;	/* are there any non-Var exprs? */
+ 
+ 	/*
  	 * Restriction clauses, divided into safe and unsafe to pushdown subsets.
  	 *
  	 * For a base foreign relation this is a list of clauses along-with
***************
*** 171,177 **** extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
  				  List **retrieved_attrs);
  extern void deparseStringLiteral(StringInfo buf, const char *val);
  extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
! extern List *build_tlist_to_deparse(RelOptInfo *foreignrel);
  extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
  						RelOptInfo *foreignrel, List *tlist,
  						List *remote_conds, List *pathkeys,
--- 194,200 ----
  				  List **retrieved_attrs);
  extern void deparseStringLiteral(StringInfo buf, const char *val);
  extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
! extern List *build_tlist_to_deparse(PlannerInfo *root, RelOptInfo *foreignrel);
  extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
  						RelOptInfo *foreignrel, List *tlist,
  						List *remote_conds, List *pathkeys,
*** a/contrib/postgres_fdw/sql/postgres_fdw.sql
--- b/contrib/postgres_fdw/sql/postgres_fdw.sql
***************
*** 499,515 **** 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;
  
! -- non-Var items in targelist of the nullable rel of a join preventing
! -- push-down in some cases
! -- unable to push {ft1, ft2}
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
- 
- -- ok to push {ft1, ft2} but not {ft1, ft2, ft4}
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
  
  -- join with nullable side with some columns with null values
  UPDATE ft5 SET c3 = null where c1 % 9 = 0;
--- 499,517 ----
  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;
  
! -- check join pushdown in situations where PHVs are involved
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
  SELECT q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15;
  EXPLAIN (VERBOSE, COSTS OFF)
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
  SELECT ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15;
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT ft2.c1, q2.* FROM ft2 LEFT JOIN (SELECT 13, q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15) q2(a2, b2, c2) ON (ft2.c1 = q2.a2) WHERE ft2.c1 BETWEEN 10 AND 15;
+ SELECT ft2.c1, q2.* FROM ft2 LEFT JOIN (SELECT 13, q.a, ft2.c1 FROM (SELECT 13 FROM ft1 WHERE c1 = 13) q(a) RIGHT JOIN ft2 ON (q.a = ft2.c1) WHERE ft2.c1 BETWEEN 10 AND 15) q2(a2, b2, c2) ON (ft2.c1 = q2.a2) WHERE ft2.c1 BETWEEN 10 AND 15;
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT ft4.c1, q2.* FROM ft4 LEFT JOIN (SELECT (q.a IS NOT NULL), ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15) q2(a2, b2, c2, d2, e2) ON (ft4.c1 = q2.b2) WHERE ft4.c1 BETWEEN 10 AND 15;
+ SELECT ft4.c1, q2.* FROM ft4 LEFT JOIN (SELECT (q.a IS NOT NULL), ft4.c1, q.* FROM ft4 LEFT JOIN (SELECT 13, ft1.c1, ft2.c1 FROM ft1 RIGHT JOIN ft2 ON (ft1.c1 = ft2.c1) WHERE ft1.c1 = 12) q(a, b, c) ON (ft4.c1 = q.b) WHERE ft4.c1 BETWEEN 10 AND 15) q2(a2, b2, c2, d2, e2) ON (ft4.c1 = q2.b2) WHERE ft4.c1 BETWEEN 10 AND 15;
  
  -- join with nullable side with some columns with null values
  UPDATE ft5 SET c3 = null where c1 % 9 = 0;
-- 
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