1 files changed, 42 insertions, 0 deletions
diff --git a/src/test/regress/sql/union.sql b/src/test/regress/sql/union.sql
index 752ae470f0d..f3c9d113827 100644
--- a/src/test/regress/sql/union.sql
+++ b/src/test/regress/sql/union.sql
@@ -207,3 +207,45 @@ explain (costs off)
    UNION ALL
    SELECT 2 AS t, * FROM tenk1 b) c
  WHERE t = 2;
+
+-- Test that we push quals into UNION sub-selects only when it's safe
+explain (costs off)
+SELECT * FROM
+  (SELECT 1 AS t, 2 AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x < 4;
+
+SELECT * FROM
+  (SELECT 1 AS t, 2 AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x < 4;
+
+explain (costs off)
+SELECT * FROM
+  (SELECT 1 AS t, generate_series(1,10) AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x < 4
+ORDER BY x;
+
+SELECT * FROM
+  (SELECT 1 AS t, generate_series(1,10) AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x < 4
+ORDER BY x;
+
+explain (costs off)
+SELECT * FROM
+  (SELECT 1 AS t, (random()*3)::int AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x > 3;
+
+SELECT * FROM
+  (SELECT 1 AS t, (random()*3)::int AS x
+   UNION
+   SELECT 2 AS t, 4 AS x) ss
+WHERE x > 3;