I have enabled second level cache for an entity. If I use entityManager.find to retrieve the entity by PK, the cache works (i.e. it hits the DB only the first time).

But if I make a HQL query on this entity, it hits the DB every time...

Here is the entity:



and here is the HQL that hits the DB every time:



Why does it hit the DB every time? Shouldn't it use the cache?

Thanks,

The second level cache is only used when accessing the object by id (pk), such as using session.get, session.load or navigating the object graph (ex Cat cat = kitten.getCat()). Searching for entities based on other attributes does not use the second level cache.

Actually the above is wrong. second level cache should work with HQL as well. Here is an excerpt from hibernate docs:



Here is the doc:
http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#performance-sessioncache

Can anybody please help

did u try this?

The above is about the query cache, but I am interested in the entity cache. Query cache does not solve my problem.

Hi again. First of all, that doc part is about the first level cache that helps manage object identity for the duration of the hibernate session. It is however true that even the second level cache (bound to the session factory) is updated based on most of theese conditions. This does not however mean that you can find an object in the cache based on an arbitary hql query.

It is possible to find an object in the cache based on a business key (not the same as the primary key). The attributes of the business key is normally composed of the attributes within the equals and hash code.

It is also possible to use a query cache. If the (exact) same query is executed more than once, the result of the query can be cached. Remember that the query cache expires on every insert, updated and delete from the affected table(s). Maybe this is what you are looking for?

The second level cache does not normally contain every entity in the database. Even if you did find one or more entities based on your example query, the cache can never guarantee that there are no other object in the database mathing your query.

Hi,
as far as I know (and as previous poster pointed) entity cache is searched when you try to retrieve entity by its id. that includes entitymanager.find() or retrieving entities referenced from other entities.
In the query you check specific fields, so id-based cache wont help much here. You need query cache.
This needs:


as well as hibernate properties set
hibernate.cache.use_second_level_cache=true
hibernate.cache.use_query_cache=true

as well as @Cache-enabling of any @Entities among:
CoreBuyer
CoreLang
CoreMessage
MessageKey
and any further entities referenced from them

Best regards
Jakub