| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: segment monitoring, stats, histograms
Jeremiah,
I have all tables in monitoring mode. And I gather stats daily using the USER_TAB_MODIFICATIONS table. Granted that I have mostly OLTP databases, but I have not yet run into a situation where the execution plan changed to something bad because of new stats being gathered. Monitoring has not impacted DML operations. And we perform a full stats gather - I never sample. I don't gather histogram stats as I have not had the need yet.
Runs fine for us.
Hope this helps.
Tom
-----Original Message-----
From: Jeremiah Wilton [mailto:jeremiah_at_ora-600.net]
Sent: Thursday, February 03, 2005 7:09 PM
To: oracle-l_at_freelists.org
Subject: segment monitoring, stats, histograms
What is the current state of the art WRT CBO best practices?
I'm working on 9.2.0.4 and considering the 'automated statistics gatherin= g' approach. This involves turning on monitoring for any and all tables = that need to ever have stats updated, then periodically running dbms_stat=s in gather_stale mode.
How is this working for people? Does monitoring impact DML operations, a= nd if so, how much?
Does this approach make any kind of intelligent decisions about sample si= zes and block sampling?
When histograms are present, does this approach always/never/sometimes re= generate the histogram with the correct number of buckets?
Does it seem to reliably choose the correct tables to analyze?
--
Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net
--
http://www.freelists.org/webpage/oracle-l
--
http://www.freelists.org/webpage/oracle-l
Received on Fri Feb 04 2005 - 07:58:16 CST
 |
 |