Re: distribution of the sleeps on the library cache latches

Hi Steve,

yes, you're absolutely right. I've inhereted that system. The shared_pool_size = 750M. I believe it's HUGE and oversized. The application code is mostly based on literal SQL. The miss rate on the shared pool is normally about 15%-20% with periodical peaks up to 50%. But the previous DBA insist that we shouldn't decrease the size of shared pool as the miss rate will be much higher. He also setup periodical flushing every 3 hours (I assume he did it in order to prevent ORA-4031). If I undestand the things right, deacresing of shared_pool_size will decrease load on shared pool latch _but_ contention on the library latches will be higher because of higher parse rate. Is it correct and what's your advice in my case?

Thanks in advance,
Ed

> Hi Ed,
>
> I would agree with the _kgl_latch_count change, but the _kgl_bucket_count
change seems unwarranted and extreme. Rather I
> suspect that the size of your library cache hash table rather reflects an
oversized shared pool, probably with some use
> of literal SQL.
>
> @ Regards,
> @ Steve Adams
> @ http://www.ixora.com.au/ - For DBAs
> @ http://www.secularislam.org/call.htm - For Muslims
> @ http://www.christianity.net.au/ - For all
>
>
> -----Original Message-----
> From: Edward Shevtsov [mailto:ed_at_mb.ru]
> Sent: Friday, 19 October 2001 18:02
> To: ORACLE-L_at_fatcity.com
> Cc: Steve Adams
> Subject: Re: distribution of the sleeps on the library cache latches
>
>
> Hi Steve,
>
> thanks for your reply. I'm thinking about twice increasing number of
> library latches ( _kgl_latch_count = 23 ) in order to mitigate loading on
> them.
> Also I would like to set _kgl_bucket_count = 8 according to output of your
> script. Do you think it's a good idea in my case.
>
> NAME IMPACT SLEEP_RATE HOLDING LEVEL#
> ------------------------- ---------- ---------- ---------- ----------
> library cache 60333579.3 0.32% 172945238 5
> shared pool 19313269.2 1.40% 8265405 7
> cache buffers chains 1950080.11 0.00% 629411 1
> row cache objects 738401.912 0.04% 3369329 4
> session allocation 70758.0784 0.01% 144008 5
> cache buffer handles 56104.2222 0.01% 71913 3
> redo allocation 33494.1227 0.02% 215582 6
> cache buffers lru chain 12784.3859 0.00% 198869 3
> checkpoint queue latch10980.4325 0.00% 52259 7
> latch wait list 9976.33016 0.04% 24412 9
> redo writing 4846.5256 0.01% 75484 5
>
> Regards,
> Ed
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Edward Shevtsov
  INET: ed_at_mb.ru

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: ListGuru_at_fatcity.com (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).