Download the YAPP paper ;-) Anjo.
John Kanagaraj wrote: > 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). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Anjo Kolk 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).