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SQL Anywhere 11.0.1 » SQL Anywhere Server - SQL Usage » Monitoring and Improving Database Performance » Improving database performance » Performance improvement tips


Dynamic cache sizing

You can use SQL Anywhere to automatically resize the database cache. However, the effectiveness of dynamic cache sizing is limited by the operating system on which the database server is running and by the amount of available physical memory.

With full dynamic cache sizing, database server performance is unaffected by the allocation of inadequate memory. The cache grows when the database server can usefully use more, as long as memory is available, and shrinks when cache memory is required by other applications. This prevents the database server from affecting other applications on the system.

Typically, the cache requirements are assessed by dynamic cache sizing once per minute. However, the assessment period may increase to once every five seconds for thirty seconds when a new database is started or when a file grows significantly. After the initial thirty second period, the sampling rate returns to once per minute. File growth of 1/8 since the database started or since the last growth that triggered an increase in the sampling rate is considered significant. This change improves performance further, by adapting the cache size more quickly when databases are started dynamically and when a lot of data is inserted.

With dynamic cache sizing you do not need to explicitly configure the database cache.

When an Address Windowing Extensions (AWE) cache is used, dynamic cache sizing is disabled. You cannot use an AWE cache on Windows Mobile.

For more information about AWE caches, see -cw server option.