Re: optimizer parameters

From: Geomancer <pharfromhome_at_hotmail.com>
Date: 7 Oct 2003 17:22:29 -0700
Message-ID: <cf90fb89.0310071622.a831aeb@posting.google.com>

I use optimizer_index_cost_adj at 20-30 for OLTP systems.

Run access.sql first to see if you have suspect large full table scans:

http://www.oracle.com/oramag/oracle/00-nov/index.html?o60dba.html

From OTN, good advice:

Rarely change CBO parameters. The CBO parameters are very dangerous because a single parameter change could adversely affect the performance of an entire enterprise. Changes to critical CBO parameters such as optimizer_mode, optimizer_index_cost_adj, and optimizer_index_caching should only be made after careful system testing.

http://otn.oracle.com/oramag/webcolumns/2003/techarticles/burleson_cbo_pt1_pt2.html Received on Tue Oct 07 2003 - 19:22:29 CDT