Setting the Buffer Cache Initialization Parameters (108)

The buffer cache initialization parameters
determine the size of the buffer cache component of the SGA. You use them to specify
the sizes of caches for the various block sizes used by the database. These initialization
parameters are all dynamic.

If you intend to use multiple block sizes in your database, you must have the
DB_CACHE_SIZE and at least one DB_nK_CACHE_SIZE parameter set. Oracle
Database assigns an appropriate default value to the DB_CACHE_SIZE parameter, but
the DB_nK_CACHE_SIZE parameters default to 0, and no additional block size caches
are configured.

The size of a buffer cache affects performance. Larger cache sizes generally reduce the
number of disk reads and writes. However, a large cache may take up too much
memory and induce memory paging or swapping.

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