The cache is an area of memory used by the database server to store database pages for repeated fast access.
The more pages that are accessible in the cache, the fewer times the database server needs to read data from disk, which is a slower operation. Cache size is therefore often a key factor in performance.
Dynamic cache sizing, which tunes the cache size appropriately and automatically by monitoring the system as a whole, is supported. You can also use the -c option on the database server command line when the database is started to control the size of the database cache.
The database server messages window displays the size of the cache at startup, but you can also use the following statement to obtain the current size of the cache:
SELECT PROPERTY( 'CurrentCacheSize' );
Encrypted databases must have sufficient cache to minimize I/O operations because these operations are more expensive on encrypted databases than on unencrypted databases since encryption and/or decryption must be performed for each operation.