Greg, > > Can I assume a i/o bottleneck from the following > > > > select * from v$system_event > > order by TIME_WAITED; > > No. Wait events may only make up a small amount of > processing that Oracle > is doing for you.
Hmm.... I wouldn't think so. If there were just _one_ overall view that I could check to determine an Oracle bottleneck, it would be this view. A rollup of V$SESSION_WAIT is also effective in determining the _current_ bottleneck. As to the original question: (And as with many other questions) It depends! The average_wait times displayed by V$SYSTEM_EVENT against specific events is a good indication of the 'bottleneck'. Just yesterday, I was debugging 'slow response' from a test database. The top wait events were for 'direct path read' and 'direct path write', with inordinate values for AV_WAIT (upto 932 CS or 9 secs!). This clearly pointed to some misconfigured Async I/O (It was on a Sun box where async_io default to TRUE). I then had the SA look at the Async config and it turns out that the Veritas layer was misconfigured - hopefully this has been sorted out. There have been numerous other examples - and I am not alone here - where DBAs have used V$SYSTEM_EVENT to determine the bottleneck. If I were 'S B', I would look at the avarage wait values for I/O and compare them to the manufacturer's claims. If they don't match or or not close, then it _may_ be an I/O bottleneck. I would recommend purchasing (or even stoop to the level of purloining a copy from a friend!) the most excellent 'Oracle Performance Tuning 101' book written by Gaja and Kirti from this list. This question is dealt in great detail therein, and I am sure they would be happy to answer any further queries. John Kanagaraj Oracle Applications DBA DBSoft Inc (W): 408-970-7002 The manuals for Oracle are here: http://tahiti.oracle.com The manual for Life is here: http://www.gospelcom.net ** The opinions and statements above are entirely my own and not those of my employer or clients ** -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: John Kanagaraj INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
