2026-03-12 20:23:15

tpt/lotslios.sql

@@ -0,0 +1,40 @@
+-- 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.
+
+--------------------------------------------------------------------------------
+--
+-- File name:   lotslios.sql
+-- Purpose:     Generate Lots of Logical IOs for testing purposes
+--
+-- Author:      Tanel Poder
+-- Copyright:   (c) http://www.tanelpoder.com
+--
+-- Usage:       @lotslios <number>
+--              @lotslios 100
+--              @lotslios 1000000
+--
+-- Other:       As the script self-joins SYS.OBJ$ to itself the maximum number
+--              of rows processed (and LIOs generated) depends on the number
+--              of rows in SYS.OBJ$
+--
+--------------------------------------------------------------------------------
+
+prompt generate lots of LIOs by repeatedly full scanning through a small table...
+
+select
+    /*+ monitor 
+        leading(a b c)
+        use_nl(b) use_nl(c) use_nl(d) 
+        full(a) full(b) full(c) full(d) */
+    count(*)
+from
+    sys.obj$ a,
+    sys.obj$ b,
+    sys.obj$ c,
+    sys.obj$ d
+where
+    a.owner# = b.owner#
+and b.owner# = c.owner#
+and c.owner# = d.owner#
+and rownum <= &1
+/