2 files changed, 72 insertions, 4 deletions

diff --git a/src/backend/executor/execScan.c b/src/backend/executor/execScan.c
index a96e826ba42..3faf7f9a77d 100644
--- a/src/backend/executor/execScan.c
+++ b/src/backend/executor/execScan.c
@@ -49,8 +49,21 @@ ExecScanFetch(ScanState *node,
 		 */
 		Index		scanrelid = ((Scan *) node->ps.plan)->scanrelid;
 
-		Assert(scanrelid > 0);
-		if (estate->es_epqTupleSet[scanrelid - 1])
+		if (scanrelid == 0)
+		{
+			TupleTableSlot *slot = node->ss_ScanTupleSlot;
+
+			/*
+			 * This is a ForeignScan or CustomScan which has pushed down a
+			 * join to the remote side.  The recheck method is responsible not
+			 * only for rechecking the scan/join quals but also for storing
+			 * the correct tuple in the slot.
+			 */
+			if (!(*recheckMtd) (node, slot))
+				ExecClearTuple(slot);	/* would not be returned by scan */
+			return slot;
+		}
+		else if (estate->es_epqTupleSet[scanrelid - 1])
 		{
 			TupleTableSlot *slot = node->ss_ScanTupleSlot;
 
@@ -347,8 +360,31 @@ ExecScanReScan(ScanState *node)
 	{
 		Index		scanrelid = ((Scan *) node->ps.plan)->scanrelid;
 
-		Assert(scanrelid > 0);
+		if (scanrelid > 0)
+			estate->es_epqScanDone[scanrelid - 1] = false;
+		else
+		{
+			Bitmapset  *relids;
+			int			rtindex = -1;
 
-		estate->es_epqScanDone[scanrelid - 1] = false;
+			/*
+			 * If an FDW or custom scan provider has replaced the join with a
+			 * scan, there are multiple RTIs; reset the epqScanDone flag for
+			 * all of them.
+			 */
+			if (IsA(node->ps.plan, ForeignScan))
+				relids = ((ForeignScan *) node->ps.plan)->fs_relids;
+			else if (IsA(node->ps.plan, CustomScan))
+				relids = ((CustomScan *) node->ps.plan)->custom_relids;
+			else
+				elog(ERROR, "unexpected scan node: %d",
+					 (int) nodeTag(node->ps.plan));
+
+			while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
+			{
+				Assert(rtindex > 0);
+				estate->es_epqScanDone[rtindex - 1] = false;
+			}
+		}
 	}
 }
diff --git a/src/backend/executor/nodeForeignscan.c b/src/backend/executor/nodeForeignscan.c
index 6165e4a6cb4..62959e3a649 100644
--- a/src/backend/executor/nodeForeignscan.c
+++ b/src/backend/executor/nodeForeignscan.c
@@ -73,6 +73,7 @@ ForeignNext(ForeignScanState *node)
 static bool
 ForeignRecheck(ForeignScanState *node, TupleTableSlot *slot)
 {
+	FdwRoutine *fdwroutine = node->fdwroutine;
 	ExprContext *econtext;
 
 	/*
@@ -85,6 +86,18 @@ ForeignRecheck(ForeignScanState *node, TupleTableSlot *slot)
 
 	ResetExprContext(econtext);
 
+	/*
+	 * If an outer join is pushed down, RecheckForeignScan may need to store a
+	 * different tuple in the slot, because a different set of columns may go
+	 * to NULL upon recheck.  Otherwise, it shouldn't need to change the slot
+	 * contents, just return true or false to indicate whether the quals still
+	 * pass.  For simple cases, setting fdw_recheck_quals may be easier than
+	 * providing this callback.
+	 */
+	if (fdwroutine->RecheckForeignScan &&
+		!fdwroutine->RecheckForeignScan(node, slot))
+		return false;
+
 	return ExecQual(node->fdw_recheck_quals, econtext, false);
 }
 
@@ -205,6 +218,11 @@ ExecInitForeignScan(ForeignScan *node, EState *estate, int eflags)
 	scanstate->fdwroutine = fdwroutine;
 	scanstate->fdw_state = NULL;
 
+	/* Initialize any outer plan. */
+	if (outerPlan(node))
+		outerPlanState(scanstate) =
+			ExecInitNode(outerPlan(node), estate, eflags);
+
 	/*
 	 * Tell the FDW to initialize the scan.
 	 */
@@ -225,6 +243,10 @@ ExecEndForeignScan(ForeignScanState *node)
 	/* Let the FDW shut down */
 	node->fdwroutine->EndForeignScan(node);
 
+	/* Shut down any outer plan. */
+	if (outerPlanState(node))
+		ExecEndNode(outerPlanState(node));
+
 	/* Free the exprcontext */
 	ExecFreeExprContext(&node->ss.ps);
 
@@ -246,7 +268,17 @@ ExecEndForeignScan(ForeignScanState *node)
 void
 ExecReScanForeignScan(ForeignScanState *node)
 {
+	PlanState  *outerPlan = outerPlanState(node);
+
 	node->fdwroutine->ReScanForeignScan(node);
 
+	/*
+	 * If chgParam of subnode is not null then plan will be re-scanned by
+	 * first ExecProcNode.  outerPlan may also be NULL, in which case there
+	 * is nothing to rescan at all.
+	 */
+	if (outerPlan != NULL && outerPlan->chgParam == NULL)
+		ExecReScan(outerPlan);
+
 	ExecScanReScan(&node->ss);
 }