Difference between revisions of "SET GCACHE"

Latest revision as of 15:57, 23 November 2009

Purpose

Enable or disable shared table and index file caching

Syntax

SET GCACHE ON | OFF | (<expL>)

See Also

SET CACHELOAD, SET DCACHE, SET ICACHE, SET PCACHE

Description

The SET GCACHE (global cache) command allows table and index file caching on shared tables. The SET DCACHE and ICACHE commands cause table records and index files to be ’cached’ in memory. Normally these commands only operate on tables that have been opened exclusively. When SET GCACHE is ON, the DCACHE and ICACHE commands handle caching on a distributed basis.

The number of records cached is specified with the SET DCACHE command. When SET GCACHE is ON, the number of records specified by the SET DCACHE command is reserved on a per user basis. Caching table records and index files accelerates only those I/O operations that access the cached records. Operations such as a sequential read of a table, or a random query, will not benefit from caching. The SET GCACHE command can be used in conjunction with the SET DCACHE and SET PCACHE commands to optimize performance.

The SET CACHELOAD command may be used with the DCACHE command to forcibly load the table and index cache into memory when the table is used. Although this can be a lengthy process, further access to the table is accelerated dramatically.

Example

// Open up payroll system
set cacheload on
set gcache on
set icache to 3000
set dcache to 1000
use payroll index pay_date, emp_code

Products

Recital Server, Recital