Hibernate cache

Hibernate cache is two types

1. First level cache : It's act as session

2. Second level cache : It's act as sessionfactory.

update more very soon.

An Introduction to Caching

Caching is widely used for optimizing database applications. A cache is designed to reduce traffic between your application and the database by conserving data already loaded from the database. Database access is necessary only when retrieving data that is not currently available in the cache. The application may need to empty (invalidate) the cache from time to time if the database is updated or modified in some way, because it has no way of knowing whether the cache is up to date.

Hibernate Caching

Hibernate uses two different caches for objects: first-level cache and second-level cache. First-level cache is associated with the Session object, while second-level cache is associated with the Session Factory object. By default, Hibernate uses first-level cache on a per-transaction basis. Hibernate uses this cache mainly to reduce the number of SQL queries it needs to generate within a given transaction. For example, if an object is modified several times within the same transaction, Hibernate will generate only one SQL UPDATE statement at the end of the transaction, containing all the modifications. This article focuses on second-level cache. To reduce database traffic, second-level cache keeps loaded objects at the Session Factory level between transactions. These objects are available to the whole application, not just to the user running the query. This way, each time a query returns an object that is already loaded in the cache, one or more database transactions potentially are avoided.

In addition, you can use a query-level cache if you need to cache actual query results, rather than just persistent objects.

Cache Implementations

Caches are complicated pieces of software, and the market offers quite a number of choices, both open source and commercial. Hibernate supports the following open-source cache implementations out-of-the-box:

• EHCache (org.hibernate.cache.EhCacheProvider)
• OSCache (org.hibernate.cache.OSCacheProvider)
• SwarmCache (org.hibernate.cache.SwarmCacheProvider)
• JBoss TreeCache (org.hibernate.cache.TreeCacheProvider)