The query cache is responsible for caching the results and to be more precise the keys of the objects returned by queries. Let us have a look how Hibernate uses the query cache to retrieve objects. In order to make use of the query cache we have to modify the person loading example as follows.
Query query = session.createQuery("from Person as p where p.parent.id=? and p.firstName=?");
query.setInt(0, Integer.valueOf(1));
query.setString(1, "Joey");
query.setCacheable(true); //caches the query
List l = query.list();
You also have to change the hibernate configuration to enable the query cache. This is done by adding the following line to the Hibernate configuration.
<property name="hibernate.cache.use_query_cache">true</property>
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.
Query query = session.createQuery("from Person as p where p.parent.id=? and p.firstName=?");
query.setInt(0, Integer.valueOf(1));
query.setString(1, "Joey");
query.setCacheable(true); //caches the query
List l = query.list();
You also have to change the hibernate configuration to enable the query cache. This is done by adding the following line to the Hibernate configuration.
<property name="hibernate.cache.use_query_cache">true</property>
Note that the query cache does not cache the state of the actual entities in the result set. It caches only identifier values and results of value type. So the query cache should always be used in conjunction 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.
