diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 654ee5849b16108310c90268da7c5b76c1f1dfb4..0b6a44cbce0932de8bb4a30a1117badd4a64c872 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -1129,7 +1129,9 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
/*
* It's possible that constraint exclusion proved the subquery empty. If
* so, it's convenient to turn it back into a dummy path so that we will
- * recognize appropriate optimizations at this level.
+ * recognize appropriate optimizations at this query level. (But see
+ * create_append_plan in createplan.c, which has to reverse this
+ * substitution.)
*/
if (is_dummy_plan(rel->subplan))
{
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 99412b6e0783d46250c1e364031e95c2c006efd4..42f58bd5c7c824468fe1cd96dfbb49a155456cca 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -664,30 +664,49 @@ static Plan *
create_append_plan(PlannerInfo *root, AppendPath *best_path)
{
Append *plan;
- List *tlist = build_relation_tlist(best_path->path.parent);
+ RelOptInfo *rel = best_path->path.parent;
+ List *tlist = build_relation_tlist(rel);
List *subplans = NIL;
ListCell *subpaths;
/*
- * It is possible for the subplans list to contain only one entry, or even
- * no entries. Handle these cases specially.
+ * The subpaths list could be empty, if every child was proven empty by
+ * constraint exclusion. In that case generate a dummy plan that returns
+ * no rows.
*
- * XXX ideally, if there's just one entry, we'd not bother to generate an
- * Append node but just return the single child. At the moment this does
- * not work because the varno of the child scan plan won't match the
- * parent-rel Vars it'll be asked to emit.
+ * Note that an AppendPath with no members is also generated in certain
+ * cases where there was no appending construct at all, but we know the
+ * relation is empty (see set_dummy_rel_pathlist).
*/
if (best_path->subpaths == NIL)
{
- /* Generate a Result plan with constant-FALSE gating qual */
- return (Plan *) make_result(root,
- tlist,
- (Node *) list_make1(makeBoolConst(false,
- false)),
- NULL);
+ /*
+ * If this is a dummy path for a subquery, we have to wrap the
+ * subquery's original plan in a SubqueryScan so that setrefs.c will
+ * do the right things. (In particular, it must pull up the
+ * subquery's rangetable so that the executor will apply permissions
+ * checks to those rels at runtime.)
+ */
+ if (rel->rtekind == RTE_SUBQUERY)
+ {
+ Assert(is_dummy_plan(rel->subplan));
+ return (Plan *) make_subqueryscan(tlist,
+ NIL,
+ rel->relid,
+ rel->subplan);
+ }
+ else
+ {
+ /* Generate a Result plan with constant-FALSE gating qual */
+ return (Plan *) make_result(root,
+ tlist,
+ (Node *) list_make1(makeBoolConst(false,
+ false)),
+ NULL);
+ }
}
- /* Normal case with multiple subpaths */
+ /* Build the plan for each child */
foreach(subpaths, best_path->subpaths)
{
Path *subpath = (Path *) lfirst(subpaths);
@@ -695,6 +714,13 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
subplans = lappend(subplans, create_plan_recurse(root, subpath));
}
+ /*
+ * XXX ideally, if there's just one child, we'd not bother to generate an
+ * Append node but just return the single child. At the moment this does
+ * not work because the varno of the child scan plan won't match the
+ * parent-rel Vars it'll be asked to emit.
+ */
+
plan = make_append(subplans, tlist);
return (Plan *) plan;
diff --git a/src/test/regress/expected/privileges.out b/src/test/regress/expected/privileges.out
index e8930cb2eb58543e45a0924a1c1a1fe846fe0ced..68afecc91f7760b9d7fbc50f58dfd59b2b70ea46 100644
--- a/src/test/regress/expected/privileges.out
+++ b/src/test/regress/expected/privileges.out
@@ -198,6 +198,8 @@ CREATE VIEW atestv1 AS SELECT * FROM atest1; -- ok
/* The next *should* fail, but it's not implemented that way yet. */
CREATE VIEW atestv2 AS SELECT * FROM atest2;
CREATE VIEW atestv3 AS SELECT * FROM atest3; -- ok
+/* Empty view is a corner case that failed in 9.2. */
+CREATE VIEW atestv0 AS SELECT 0 as x WHERE false; -- ok
SELECT * FROM atestv1; -- ok
a | b
---+-----
@@ -224,6 +226,8 @@ SELECT * FROM atestv3; -- ok
-----+-----+-------
(0 rows)
+SELECT * FROM atestv0; -- fail
+ERROR: permission denied for relation atestv0
CREATE VIEW atestv4 AS SELECT * FROM atestv3; -- nested view
SELECT * FROM atestv4; -- ok
one | two | three
@@ -1386,6 +1390,7 @@ drop table dep_priv_test;
drop sequence x_seq;
DROP FUNCTION testfunc2(int);
DROP FUNCTION testfunc4(boolean);
+DROP VIEW atestv0;
DROP VIEW atestv1;
DROP VIEW atestv2;
-- this should cascade to drop atestv4
diff --git a/src/test/regress/sql/privileges.sql b/src/test/regress/sql/privileges.sql
index d4d328e649f7244dd8cb520058849221aab40edf..6ac3378a8d003e8204b1bc1fd3e85b046cd7fd2c 100644
--- a/src/test/regress/sql/privileges.sql
+++ b/src/test/regress/sql/privileges.sql
@@ -147,6 +147,8 @@ CREATE VIEW atestv1 AS SELECT * FROM atest1; -- ok
/* The next *should* fail, but it's not implemented that way yet. */
CREATE VIEW atestv2 AS SELECT * FROM atest2;
CREATE VIEW atestv3 AS SELECT * FROM atest3; -- ok
+/* Empty view is a corner case that failed in 9.2. */
+CREATE VIEW atestv0 AS SELECT 0 as x WHERE false; -- ok
SELECT * FROM atestv1; -- ok
SELECT * FROM atestv2; -- fail
@@ -158,6 +160,7 @@ SET SESSION AUTHORIZATION regressuser4;
SELECT * FROM atestv1; -- ok
SELECT * FROM atestv2; -- fail
SELECT * FROM atestv3; -- ok
+SELECT * FROM atestv0; -- fail
CREATE VIEW atestv4 AS SELECT * FROM atestv3; -- nested view
SELECT * FROM atestv4; -- ok
@@ -828,6 +831,7 @@ drop sequence x_seq;
DROP FUNCTION testfunc2(int);
DROP FUNCTION testfunc4(boolean);
+DROP VIEW atestv0;
DROP VIEW atestv1;
DROP VIEW atestv2;
-- this should cascade to drop atestv4