Re: Actual Buffer Pool size

goforticket_at_yahoo.com (Linda Lee) wrote in message news:<f901fb80.0305271341.2decaf40_at_posting.google.com>...
> buffer_pool_keep = (50000,2)
> buffer_pool_recycle = (30000,2)

IIRC, the correct syntax is:

buffer_pool_keep = (buffers:50000,LRU_LATCHES:2) and so on.

> RECYCLE is 1. Why they take only one (instead of 2)? Is there a better

Probably because of the syntax thing above. Have a look at the 8.1.7 specific doco.

BTW, your cache size is probably a tad too large. You sure you need THAT MANY buffers? No, don't use the buffer-cache-hit-ratio to answer.

> I query dba_segments to get the actual sizes of pools. Is there a
> beeter way to get the actuall/real size of each pool? Why the size of
> DEFAULT pool is much larger than what I allocated by init parameters?
> Do I need to increase the size for DEFAULT pool?

Why do you assume that the pool size has got to match the size of the objects assigned to it?
Isn't this a (partitioned) cache? Why do you assume a cache has to contain the totality of objects that can be cached?

Think if it as being like any other cache: it contains the most USED objects. No need to contain ALL of them, used or not! Same as the file system cache in Win2000: it does not NEED to be sized to the total disk space you have for it to be effective. Same principle.

DBA_SEGMENTS describes the totality of storage objects in the database. The total physocal size of the data. This does not mean they ALL have to be cached at the same time. Another hint: an index is cacheable object as well. Not just tables.

HTH
Nuno Souto
wizofoz2k_at_yahoo.com.au.nospam Received on Tue May 27 2003 - 21:56:39 CDT