Saturday, 17 August 2013

DB2 Buffer Pool

An area of memory into which database pages are read, modified, and held during processing.
The database buffer pool is a piece of real memory used by DB2 to temporarily store (cache) regular data and index pages when they are read from disk to be scanned or modified.
The buffer pool improves the performance of the database because the pages can be accessed much more quickly from memory than from disk.
When you create a database, a default buffer pool, IBMDEFAULTBP, is automatically created. This buffer pool is associated with the default table spaces SYSCATSPACE, TEMPSPACE1, and USERSPACE1, and you cannot drop it.
To create a buffer pool, use the CREATE BUFFERPOOL statement. This statement allows you to indicate, among other things, how large the buffer pool will be and which page size it will use.
Example :
                   SIZE 100000
                   PAGESIZE 16K
                   NUMBLOCKPAGES 24000
                   BLOCKSIZE 256

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