JPA 2.0 Cache APIs

JPA 2.0 provides a set of standard query hints to allow refreshing or bypassing the cache. The query hints are defined on the two enum classes CacheRetrieveMode and CacheStoreMode.

Query hints:

• javax.persistence.cache.retrieveMode : CacheRetrieveMode
  • BYPASS : Ignore the cache, and build the object directly from the database result.
  • USE : Allow the query to use the cache. If the object/data is already in the cache, the cached object/data will be used.
• javax.persistence.cache.storeMode : CacheStoreMode
  • BYPASS : Do not cache the database results.
  • REFRESH : If the object/data is already in the cache, then refresh/replace it with the database results.
  • USE : Cache the objects/data returned from the query.

Cache hints example

Query query = em.createQuery("Select e from Employee e");
query.setHint("javax.persistence.cache.storeMode", CacheStoreMode.REFRESH);