JdbcStringBasedCacheStore loads previous data from store before an insert

The JdbcStringBasedCacheStore implementation loads the previous data on an insert to find out if it should generate an UPDATE or INSERT statement, while it would perform much better to just verify if the primary key exists.

On top of this, some databases provide ways to avoid the need to check at all, like MySQL's " INSERT ... ON DUPLICATE KEY UPDATE"
http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html