CBO vrs Rule

From: Christopher Spence <nospam_at_cspence@delphi-tech.com>
Date: 2000/03/01
Message-ID: <38bd39de$0$3481@wodc7nh0.news.uu.net>#1/1

Anyone have any experience with problems with CBO in 7.3.x?

Full schema Analyze, 25% Estimate Statistics 3 days later
3 tables join queried with hint /*+ rule */ Results: 240ms
3 tables join queried with no hints (use CBO as there is statistics) Results: 2300ms
Manually Analyze the 3 tables
3 tables join queried with no hints (use CBO as there is statistics) Results: 220ms

Comparing statistics between 3 days ago and today, the data (row_num, avg_row_leng, blocks and such) where around 1% or even less than what the analyze did last time, very few things if anything changed in this schema since then but performance was drastically effected. The main reason for the performance change is a use of a FTS on one of the tables prior to doing re-analyze Received on Wed Mar 01 2000 - 00:00:00 CST