Sybase Prefetch

prefetch improves performance by anticipating the pages required for certain well-defined classes of database activities whose access patterns are predictable. The I/O requests for these pages are issued before the query needs them so that most pages are in cache by the time query processing needs to access the page. Asynchronous prefetch can improve performance for:



Sequential scans, such as table scans, clustered index scans, and covered nonclustered index scans



Access via nonclustered indexes



Some dbcc checks and update statistics



Recovery