2026-03-12 20:23:15

tpt/demos/scalar_subquery_unnesting.sql

@@ -0,0 +1,39 @@
+-- Copyright 2018 Tanel Poder. All rights reserved. More info at http://tanelpoder.com
+-- Licensed under the Apache License, Version 2.0. See LICENSE.txt for terms & conditions.
+
+-- DROP TABLE test_users;
+-- DROP TABLE test_objects;
+CREATE TABLE test_users  AS SELECT * FROM all_users;
+CREATE TABLE test_objects AS SELECT * FROM all_objects;
+@gts test_users
+@gts test_objects
+
+@53on 
+
+SELECT /*+ GATHER_PLAN_STATISTICS */
+    u.username
+  , (SELECT MAX(created) FROM test_objects o WHERE o.owner = u.username)
+FROM
+    test_users u
+WHERE
+    username LIKE 'S%'
+/
+
+@53off
+@xall
+@53on
+
+-- ALTER SESSION SET "_optimizer_unnest_scalar_sq" = FALSE;
+
+SELECT /*+ GATHER_PLAN_STATISTICS NO_UNNEST(@ssq) */
+    u.username
+  , (SELECT /*+ QB_NAME(ssq) */ MAX(created) FROM test_objects o WHERE o.owner = u.username)
+FROM
+    test_users u
+WHERE
+    username LIKE 'S%'
+/
+
+@53off
+@xall
+