RE: CBO irregularity
- From: "Justin Cave" <justin@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 7 Jun 2004 17:50:35 -0600
I believe the comment is intended to reflect the fact that old statistics
may well be valid statistics. If you gathered statistics a year ago and the
data hasn't changed substantially, the statistics would still be valid.
Many DBA's don't gather statistics on a regular basis so as not to disrupt a
production database with acceptable plans.
Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jacques Kilchoer
Sent: Monday, June 07, 2004 5:46 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: CBO irregularity
When would up-to-date statistics not be valid? Do you mean, for example, a
different number of histograms or different sample sizes were collected with
the "up-to-date" statistics?
-----Original Message-----
Daniel Fink
...
If you don't have valid (not the
same as up-to-date) statistics on all the objects (and corollary
objects) referenced in the query, you might get some defaults that are
unrealistic or it may perform dynamic sampling.
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