Hibernate Caching

Hibernate Caching

Caching is all about application performance optimization and it sits between your application and the database to avoid the number of database hits as many as possible to give a better performance.

First-level cache:

The first-level cache is the Session cache and is a mandatory cache through which all requests must pass. The Session object keeps an object under its own power before committing it to the database.

If you issue multiple updates to an object, Hibernate tries to delay doing the update as long as possible to reduce the number of update SQL statements issued. If you close the session, all the objects being cached are lost and either persisted or updated in the database.

Second-level cache:

Second level cache is an optional cache and first-level cache will always be consulted before any attempt is made to locate an object in the second-level cache. The second-level cache can be configured on a per-class and per-collection basis and mainly responsible for caching objects across sessions.

Any third-party cache can be used with Hibernate. An org.hibernate.cache.CacheProvider interface is provided, which must be implemented to provide Hibernate with a handle to the cache implementation.

Query-level cache:

Hibernate also implements a cache for query result sets that integrates closely with the second-level cache. This is an optional feature and requires two additional physical cache regions that hold the cached query results and the timestamps when a table was last updated. This is only useful for queries that are run frequently with the same parameters. Every time the query is fired the cache manager checks for the combination of parameters and query. If the results are found in the cache they are returned otherwise a database transaction is initiated.

<property name="hibernate.cache.use_query_cache">true</property>