on 04-04-2007 8:37 PM
How many of you have been using db_keep_cache_size Oracle parameter in your SAP databases?
We use db_keep_cache_size for some of our non-SAP databases and we haven't seen any harm by doing so. Basically you are asking Oracle to keep the tables like look-up tables in it's own cache and that won't be thrown out frm the cache with a large table read.
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If an object grows in size, then it might no longer fit in the KEEP buffer pool. You will begin to lose blocks out of the cache.
Each object kept in memory results in a trade-off. It is beneficial to keep frequently-accessed blocks in the cache, but retaining infrequently-used blocks results in less space for other, more active blocks.
Hi Anup,
The db_keep_cache _size is configured together with some other cache parameters like
db_cache_size
db_recycle_cache size
db_nk_cache_size
and the total buffer cache and the standard block size.
This cannot be configured in isolation without the above parameters.
The buffer cache consists of independent subcaches for buffer pools and for multiple block
sizes. The DB_BLOCK_SIZE parameter determines the primary block size, which is used for
the SYSTEM tablespace. DB_CACHE_SIZE,DB_KEEP_CACHE_SIZE,DB_RECYCLE_CACHE_SIZE parameters
define the sizes of the caches for buffers for the primary block size.
The new value of DB_CACHE_SIZE refers only to the size of the DEFAULT buffer pool versus
total size of the DEFAULT, KEEP, and RECYCLE buffer pools.
If tablespaces with different block size are used, then buffers for the block size must
be allocated. You must not use the DB_nK_CACHE_SIZE parameter that matches
the DB_BLOCK_SIZE value.
However we r not using the same.
Not very sure about the outome. First try in a single oracle instance befor using it with sap database.
Dont forget to award suitable points.
Regards
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Hi,
Ref Note 762808.
For our SAP Databases till today we havent used this setting.
Regards
Vinod
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