From 590fc5d96f8b880fd41c4992dab73ec47f90eca4 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 12 Mar 2015 13:38:49 -0400
Subject: [PATCH] Ensure tableoid reads correctly in EvalPlanQual-manufactured
 tuples.

The ROW_MARK_COPY path in EvalPlanQualFetchRowMarks() was just setting
tableoid to InvalidOid, I think on the assumption that the referenced
RTE must be a subquery or other case without a meaningful OID.  However,
foreign tables also use this code path, and they do have meaningful
table OIDs; so failure to set the tuple field can lead to user-visible
misbehavior.  Fix that by fetching the appropriate OID from the range
table.

There's still an issue about whether CTID can ever have a meaningful
value in this case; at least with postgres_fdw foreign tables, it does.
But that is a different problem that seems to require a significantly
different patch --- it's debatable whether postgres_fdw really wants to
use this code path at all.

Simplified version of a patch by Etsuro Fujita, who also noted the
problem to begin with.  The issue can be demonstrated in all versions
having FDWs, so back-patch to 9.1.
---
 src/backend/executor/execMain.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index ea81c361eda..df6af1b898c 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -2238,7 +2238,9 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 			/* build a temporary HeapTuple control structure */
 			tuple.t_len = HeapTupleHeaderGetDatumLength(td);
 			ItemPointerSetInvalid(&(tuple.t_self));
-			tuple.t_tableOid = InvalidOid;
+			/* relation might be a foreign table, if so provide tableoid */
+			tuple.t_tableOid = getrelid(erm->rti,
+										epqstate->estate->es_range_table);
 			tuple.t_data = td;
 
 			/* copy and store tuple */
-- 
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