10.2.2 Automatic Flash Caching for Table Scan Workloads

Oracle Exadata Storage Server Software automatically caches objects read by table and partition scan workloads in flash cache based on how frequently the objects are read. The algorithm takes into account the size of the object, the frequency of access of the object, the frequency of access to data displaced in the cache by the object, and the type of scan being performed by the database. Depending on the flash cache size, and the other concurrent workloads, all or only part of the table or partition is cached. There is no risk of thrashing the flash cache by trying to cache an object that is large compared to the size of the flash cache, or by caching a table that is accessed by maintenance operations.

This feature largely eliminates the need for manually keeping tables in flash cache except to guarantee low response times for certain objects at the expense of potentially increasing total disk I/Os. In earlier releases, database administrators had to mark a large object as KEEP to have it cached in flash cache for table scan workloads.

This feature primarily benefits table scan intensive workloads such as Data Warehouses and Data Marts. Random I/Os such as those performed for Online Transaction Processing (OLTP) continue to be cached in the flash cache the same way as in earlier releases.

Minimum software: Oracle Exadata Storage Server Software release 11.2.3.3