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Oracle Tips by Burleson |
Use of the KEEP Pool
The KEEP database buffer pool is configured using the
BUFFER_POOL_KEEP initialization parameter, which looks like this:
BUFFER_POOL_KEEP = ‘100,2’
In Oracle9i, this becomes DB_KEEP_CACHE_SIZE and is specified in
megabytes.
The two specified parameters are, respectively, the number of
buffers from the default pool to assign to the KEEP pool and the
number of LRU (least recently used) latches to assign to the KEEP
pool. The minimum number of buffers assigned to the pool is 50 times
the number of assigned latches. The KEEP pool, as its name implies,
is used to store object data that shouldn’t be aged out of the
buffer pool, such as lookup information and specific
performance-enhancing indexes. The objects are assigned to the KEEP
pool either through their creation statement or by specifically
assigning them to the pool using the ALTER command. Blocks already
in the default pool are not affected by the ALTER command, only
subsequently accessed blocks are.
The KEEP pool should be sized such that it can hold all the blocks
from all of the tables created with the buffer pool set to KEEP.
This is an excerpt by Mike Ault’s book “Oracle9i
Administration & Management” . If you want more current Oracle
tips by Mike Ault, check out his new book “Mike
Ault’s Oracle Internals Monitoring & Tuning Scripts” or Ault’s
Oracle Scripts Download. |
