8.1.7.4 Windows 2000 Server ca.200 sessions, about 30 active. About a dozen sessions go into waits for Library Cache Lock for the best part of 300 seconds. (At which they probably all get ORA-04021 and free themselves, but I couldn't tell, the problem happened a few minutes before I was due to leave the site, and the end-users were on the other side of the Atlantic). The odd session might get a library cache pin wait. The object they were waiting for (tracked via x$kglob.kglhdadr = v$session_wait.p1raw) was a table. No-one has done ANYTHING untoward to the table, such as truncate, add column, index, analyze, for at least 3 days. The table is a normal heap table with half a dozen indexes. The best bet I could come up with was a metalink item that mentioned conflicts relating to materialized views - and there is a materialized view log on this table. The only other relevant detail I could come up with is that sessions create a session, work hard for a few seconds, then drop the session (maintaining the connection) so the system may be exercising some part of the code that creates x$kgllk items rather more heavily than is normal. Any thoughts ? Any similar experiences ? Regards Jonathan Lewis http://www.jlcomp.demon.co.uk The educated person is not the person who can answer the questions, but the person who can question the answers -- T. Schick Jr Next public appearances: Jan 29th 2004 UKOUG Unix SIG - v$ and x$ March 2004 Hotsos Symposium - The Burden of Proof March 2004 Charlotte NC OUG - CBO Tutorial April 2004 Iceland One-day tutorials: http://www.jlcomp.demon.co.uk/tutorial.html Three-day seminar: see http://www.jlcomp.demon.co.uk/seminar.html ____UK___February ____UK___June The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.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 -----------------------------------------------------------------