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Oracle Tips by Burleson |
Use of the RECYCLE Pool
The RECYCLE database buffer pool is configured using the
BUFFER_POOL_RECYCLE initialization parameter, which looks like this:
BUFFER_POOL_RECYCLE = ‘1000,5’
In Oracle9i, this becomes DB_RECYCLE_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 RECYCLE 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 RECYCLE pool, as its name
implies, is used to store object data that should be aged out of the
buffer pool rapidly, such as searchable LOB information. The objects
are assigned to the RECYCLE 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.
As long as the RECYCLE pool shows low block contention, it is sized
correctly. With the above setpoints for the default, KEEP and
RECYCLE pools, the default pool would end up with 900 buffers and 3
LRU latches.
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. |
