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


Dynamic cache sizing on Windows

On Windows and Windows Mobile, the database server evaluates cache and operating statistics once per minute and computes an optimum cache size. The database server computes a target cache size that uses all physical memory currently not in use, except for approximately 5 MB that is to be left free for system use. The target cache size is never smaller than the specified or implicit minimum cache size. The target cache size never exceeds the specified or implicit maximum cache size, or the sum of the sizes of all open database and temporary files plus the size of the main heap.

To avoid cache size oscillations, the database server increases the cache size incrementally. Rather than immediately adjusting the cache size to the target value, each adjustment modifies the cache size by 75% of the difference between the current and target cache size.

Windows can use Address Windowing Extensions (AWE) to support large cache sizes by specifying the -cw command line option when starting the database server. AWE caches do not support dynamic cache sizing. Windows Mobile does not support AWE caches. See -cw server option.