RE: Growth pattern statistics collection after analyzing

From: Allen, Brandon <Brandon.Allen_at_OneNeck.com>
Date: Tue, 26 Jul 2005 09:05:50 -0700
Message-ID: <04DDF147ED3A0D42B48A48A18D574C4502361339@NT15.oneneck.corp>

For monitoring growth patterns, you can just query dba_segments or dba_tables and dba_indexes (after a regular analyze/dbms_stats.gather_*_stats), depending on exactly what you want to monitor - segment size, used/free space, HWM, etc. Index_stats (populated by analyze . . . validate structure, which requires an exclusive lock) is typically only needed if you want to check for index sparseness, selectivity, density, the infamous out-of-balance myth, etc. In my experience, these things are only needed occasionally for troubleshooting performance problems, or if you're bored and just want to rebuild some indexes to make it look like you're busy :-)

I usually just run dbms_stats.gather_schema_stats, with either compute, or estimate as appropriate for your environment, and cascade=>true. Don't bother creating histograms (larger than the default of 1 bucket) unless justified by some specific problem, such as a query using a poor execution plan due to inaccurate estimation of the cardinality because of skewed data distribution.

Regards,
Brandon

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Johnson, George Sent: Tuesday, July 26, 2005 6:43 AM
To: 'oracle-l_at_freelists.org'
Subject: Growth pattern statistics collection after analyzing

We are currently using the traditional analyze command for both tables and indexes once a week. I have the job of converting our shell script based analyze scripts to in DB pl\sql based mechanisms.

On the subject of statistics collection, we currently seem to spend and inordinate amount of time collecting all sorts of obscure statistics about tables and indexes, I would like to simplify this to keep a more simple set of statistics, to determine our growth patterns. The dbms_stats package doesn't seem to support options like the use of the old index_stats table, so I was wondering what other people were doing in terms of stats collection for monitoring growth patterns, when using dbms_stats.

Any thoughts you could share, would be most welcome

Rgds

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http://www.freelists.org/webpage/oracle-l Received on Tue Jul 26 2005 - 11:06:32 CDT