When a query needs a data page, Adaptive Server first checks to see if the page is available in a data cache. If the page is not available, then it must be read from disk. A newly installed Adaptive Server has a single data cache configured for 2K I/O. Each I/O operation reads or writes a single Adaptive Server data page. A System Administrator can:
Configure multiple caches
Bind tables, indexes, or text chains to the caches
Configure data caches to perform I/O in page-sized multiples, up to eight data pages (one extent)
To use these caches most efficiently, and reduce I/O operations, the Adaptive Server optimizer can:
Choose to prefetch up to eight data pages at a time
Choose between different caching strategies
