Include result relation info in direct modify ForeignScan nodes.

FDWs that can perform an UPDATE/DELETE remotely using the "direct modify"
set of APIs need to access the ResultRelInfo of the target table. That's
currently available in EState.es_result_relation_info, but the next
commit will remove that field.

This commit adds a new resultRelation field in ForeignScan, to store the
target relation's RT index, and the corresponding ResultRelInfo in
ForeignScanState. The FDW's PlanDirectModify callback is expected to set
'resultRelation' along with 'operation'. The core code doesn't need them
for anything, they are for the convenience of FDW's Begin- and
IterateDirectModify callbacks.

Authors: Amit Langote, Etsuro Fujita
Discussion: https://www.postgresql.org/message-id/CA%2BHiwqGEmiib8FLiHMhKB%2BCH5dRgHSLc5N5wnvc4kym%2BZYpQEQ%40mail.gmail.com

1 files changed, 9 insertions, 7 deletions

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index a31abce7c99..78facb8ebfa 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -451,6 +451,7 @@ static void init_returning_filter(PgFdwDirectModifyState *dmstate,
 								  List *fdw_scan_tlist,
 								  Index rtindex);
 static TupleTableSlot *apply_returning_filter(PgFdwDirectModifyState *dmstate,
+											  ResultRelInfo *resultRelInfo,
 											  TupleTableSlot *slot,
 											  EState *estate);
 static void prepare_query_params(PlanState *node,
@@ -2287,9 +2288,10 @@ postgresPlanDirectModify(PlannerInfo *root,
 	}
 
 	/*
-	 * Update the operation info.
+	 * Update the operation and target relation info.
 	 */
 	fscan->operation = operation;
+	fscan->resultRelation = resultRelation;
 
 	/*
 	 * Update the fdw_exprs list that will be available to the executor.
@@ -2355,7 +2357,7 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
 	 * Identify which user to do the remote access as.  This should match what
 	 * ExecCheckRTEPerms() does.
 	 */
-	rtindex = estate->es_result_relation_info->ri_RangeTableIndex;
+	rtindex = node->resultRelInfo->ri_RangeTableIndex;
 	rte = exec_rt_fetch(rtindex, estate);
 	userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
 
@@ -2450,7 +2452,7 @@ postgresIterateDirectModify(ForeignScanState *node)
 {
 	PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
 	EState	   *estate = node->ss.ps.state;
-	ResultRelInfo *resultRelInfo = estate->es_result_relation_info;
+	ResultRelInfo *resultRelInfo = node->resultRelInfo;
 
 	/*
 	 * If this is the first call after Begin, execute the statement.
@@ -4086,7 +4088,7 @@ get_returning_data(ForeignScanState *node)
 {
 	PgFdwDirectModifyState *dmstate = (PgFdwDirectModifyState *) node->fdw_state;
 	EState	   *estate = node->ss.ps.state;
-	ResultRelInfo *resultRelInfo = estate->es_result_relation_info;
+	ResultRelInfo *resultRelInfo = node->resultRelInfo;
 	TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
 	TupleTableSlot *resultSlot;
 
@@ -4141,7 +4143,7 @@ get_returning_data(ForeignScanState *node)
 		if (dmstate->rel)
 			resultSlot = slot;
 		else
-			resultSlot = apply_returning_filter(dmstate, slot, estate);
+			resultSlot = apply_returning_filter(dmstate, resultRelInfo, slot, estate);
 	}
 	dmstate->next_tuple++;
 
@@ -4230,10 +4232,10 @@ init_returning_filter(PgFdwDirectModifyState *dmstate,
  */
 static TupleTableSlot *
 apply_returning_filter(PgFdwDirectModifyState *dmstate,
+					   ResultRelInfo *resultRelInfo,
 					   TupleTableSlot *slot,
 					   EState *estate)
 {
-	ResultRelInfo *relInfo = estate->es_result_relation_info;
 	TupleDesc	resultTupType = RelationGetDescr(dmstate->resultRel);
 	TupleTableSlot *resultSlot;
 	Datum	   *values;
@@ -4245,7 +4247,7 @@ apply_returning_filter(PgFdwDirectModifyState *dmstate,
 	/*
 	 * Use the return tuple slot as a place to store the result tuple.
 	 */
-	resultSlot = ExecGetReturningSlot(estate, relInfo);
+	resultSlot = ExecGetReturningSlot(estate, resultRelInfo);
 
 	/*
 	 * Extract all the values of the scan tuple.