Caching:

Cache:

Oracle BI Server can be configured to maintain a disk-based cache of query results sets:
• Saves the results of queries in cache files
• Enables Oracle BI Server to satisfy subsequent query requests without having to access back-end databases

Overhead because of Caching:
• Disk space
– Query cache requires dedicated disk space.
• Administrative tasks:
– Set the cache persistence time appropriately.
– Purge the cache when necessary.
• Keeping the cache up-to-date:
– Evaluate what level of noncurrent information is acceptable.
– Remove stale data.

Cache Management Techniques
• Configuring the cache parameters
• Setting caching and cache persistence for tables
• Using the Cache Manager
• Inspecting SQL for cache entries
• Modifying the Cache Manager column display
• Inspecting the cache reports
• Purging the cache entries manually using the Cache
Manager
• Purging the cache entries automatically
• Using event polling tables
• Seeding the cache

Cache Hit Conditions
A cache hit occurs only when certain conditions are met, such
as the following:
• Query WHERE clause constraints need to be equivalent to the cached results or to a subset of the results.
• All the columns in the SELECT list of a new query must exist in the cached query or they must be able to be calculated from the columns in the query.
• Join conditions must be equivalent.
• Queries that request an aggregated level of information can use cached results at a lower level of aggregation.