1 files changed, 12 insertions, 0 deletions
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index 7992191f79d..a75462b02af 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -254,6 +254,18 @@ foreign_expr_walker(Node *node,
 					var->varlevelsup == 0)
 				{
 					/* Var belongs to foreign table */
+
+					/*
+					 * System columns other than ctid should not be sent to
+					 * the remote, since we don't make any effort to ensure
+					 * that local and remote values match (tableoid, in
+					 * particular, almost certainly doesn't match).
+					 */
+					if (var->varattno < 0 &&
+						var->varattno != SelfItemPointerAttributeNumber)
+						return false;
+
+					/* Else check the collation */
 					collation = var->varcollid;
 					state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;
 				}