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 dbeng12/dbsrv12 server option (deprecated).
The use of AWE is deprecated. It is recommended that you use the 64-bit version of the SQL Anywhere database server on a 64-bit Windows operating system if you require a large cache.
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2010, iAnywhere Solutions, Inc. - SQL Anywhere 12.0.0|