It may have changed in 9, but I'm pretty sure the keep, recycle pools are not "identical" to the default cache in terms of the hot/cold boundary. You could always tweak the relevant underscore parms to make them all the same - but you'd want to be very sure that you could get maximal use out of them all of the time.
Since the advent of IOT's I haven't seen much great benefits in keep pools, but I do like recycle pools mainly to avoid someone munching more buffer cache with silly queries. hth connor --- [EMAIL PROTECTED] wrote: > > Hello, > > Env: 9.2.0.2 on Solaris 2.9 > > We are currently considering a proposal regarding > the use of the 3 > buffer pools represented by db_cache_size, > db_keep_cache_size, > and db_recycle_cache_size. I am wondering if this is > a good idea > or a bad idea. The proposal follows. > > >> > The buffer pool space can be divided into 3 separate > pools: db_cache_size, db_keep_cache_size, and > db_recycle_cache_size. > Despite the names, the blocks are all treated > exactly the same with > regard to the Least Recently Used (LRU) algorithm. > The retention time > of a database block in any of these pools is > dependent upon the size > of the pool, how often the block is referenced, and > the probability > of the block being displaced by a more popular > block. > > The names Oracle has assigned to these pools reflect > more of an intention > than anything else; the keep pool is intended to be > sized large enough > to retain all frequently-referenced data; the > recycle pool is intended to > be sized small to recycle blocks not desired in > memory, and the db_cache_size > pool is intended for everything else. > > Funtionally, Oracle could have named these > db_cache1, db_cache2 and db_cache3. > > Currently, we utilize just 1 cache, the > db_cache_size. I am proposing that > we utilize all 3 caches in some way; the rationale > for this is that it is better to > have 3 smaller caches of 800M, each managing 1000 > objects, than it is to have 1 large > cache of 2.4G managing 3000 objects. > >> > > The rest of this proposal suggests a method for > distributing the various tables > and indexes in our system to the 3 caches; it > suggests a roughly equal division > among the 3 caches based upon subject area and usage > stats. > > 1) Is the information above accurate? > 2) Is it better to have 3 smaller caches than 1 > large cache? (Assuming the objects > are distributed among the caches about equally > based upon usage stats) > > Thanks to those who read this far. > More thanks to any responders. > Most thanks to responders with helpful suggestions. > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.net > -- > Author: > 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). > ===== Connor McDonald web: http://www.oracledba.co.uk web: http://www.oaktable.net email: [EMAIL PROTECTED] "GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day" __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?iso-8859-1?q?Connor=20McDonald?= 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).
