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. ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------