patch 4.0

unittest/sql/rewrite/test_transformer_set_op.sql

@@ -1,17 +1,17 @@
 ## 
-
+# distinct 下压(有才limit 下压)
 select c1 from t1 union select c2 from t2;
-
+# 下压
 select c1 from t1 union select c2 from t2 limit 2;
 select c1 from t1 minus select c2 from t2 limit 2;
 select c1 from t1 limit 2 union select c2 from t2;
 
-
+# limit 下压(只有union all下压)
 select c1 from t1 union all select c2 from t2 limit 2;
 select c1 from t1 limit 5 union all select c2 from t2 limit 2;
 select c1 from t1 intersect select c2 from t2 limit 2;
 
-
+# order by 下压
 select c1 from t1 union all select c2 from t2 order by c1;
 select c1 from t1 union all select c2 from t2 order by c1 limit 2;
 select c1, c2 from t1 order by c2 union all select c1, c2 from t2 order by c1 limit 2;