Neil, Does this application use a lot of literal SQL? Do the users tend to use the same Appl processes during the peak times? And do they really complain about poor performance during the peak times?
The contention could be due to the excessive parsing. Since you are noticing this at all your sites, it sounds like more of a SQL issue. Sharing of cursors, use of bind variables will help. Think of increasing SHARED_POOL_SIZE only when all other avenues to reduce this contention have been explored (and rejected). But a large shared_pool_size may worsen this situation. If you have access to Metalink, Note# 1012049.6 (and other notes referenced in there) may be of some help. You can also consider use of Statspack, during the peak times (if the version of your database supports Statspack). - Kirti -----Original Message----- Sent: Friday, January 31, 2003 5:09 AM To: Multiple recipients of list ORACLE-L We've got about 30 sites all running the same application, and I'm consistently seeing large numbers of 106 (library cache) latch free waits. They tend to happen at peak times during the day, and in the worst case I saw 12 sessions all on a 106 latch free wait event, spread across 3 P1RAW addresses. Running Steve Adams latch_sleeps scripts, yields the following: LATCH TYPE IMPACT SLEEP RATE WAITS HOLDING LEVEL ------------------------------------- ----------- ---------- ------------- ----- library cache 1281502 0.11% 2399666 5 cache buffers chains 273556 0.00% 23049 1 shared pool 73893 0.04% 91633 7 cache buffers lru chain 12236 0.01% 70756 3 session allocation 10639 0.06% 19969 5 row cache objects 7835 0.00% 29816 4 cache buffer handles 3646 0.00% 2575 3 transaction allocation 2344 0.01% 4341 8 enqueue hash chains 1831 0.01% 13722 4 redo writing 778 0.01% 17328 5 session idle bit 714 0.00% 0 1 The results above are from an instance which has been up for 5 days As you can see, library cache latch has a big impact (though I must admit, I'm not sure what Steve's IMPACT formula actually tells me). When I check across other sites, I see a similar pattern - large numbers of 106 latch misses and sleeps. I guess what I'd like to know is where these latches are happening, which objects / cursors etc are causing the contention. I've grappled with SQL against x$kglob, trying to join back to the P1RAW but am not getting very far. Any ideas? TIA. Neil. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Deshpande, Kirti INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- 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).
