The following are some programming tips in relation to the different caching levels in Hibernate:

• Make sure to use the same version of hibernate-ehcache as the version of Hibernate.
• Since Hibernate caches all of the objects into the session first level cache, when running bulk queries or batch updates, it's necessary to clear the cache at certain intervals to avoid memory issues.
• When caching an entity using the second level cache, collections inside of the entity are not cached by default. In order to cache the collections, annotate the collections within the entity with @Cacheable and @org.hibernate.annotations.Cache(usage = CacheConcurrencyStrategy.READ_WRITE). Each collection is stored in a separate region in the second level cache, where the region name is the fully qualified name of the entity class, plus the name of the collection property. Define the expiration and eviction policy separately for each collection that's cached.
• When DML statements are executed using JPQL, the cache for those entities will be updated/evicted by Hibernate; however, when using the native query, the entire second level cache will be evicted, unless the following detail is added to native query execution when using Hibernate with JPA:

Query nativeQuery = entityManager.createNativeQuery("update Account set name='xyz' where name='abc'");

nativeQuery.unwrap(org.hibernate.SQLQuery.class).addSynchronizedEntityClass(Account.class);

nativeQuery.executeUpdate();

• In the case of query caching, there will be one cache entry for each combination of query and parameter values, so queries, where different combinations of parameter values are expected, are not good for caching.
• In the case of query caching, a query that fetches the entity classes for which there are frequent changes in the database is not a good candidate for caching, because the cache will be invalidated when any entity involved in the query is changed.
• All query cache results are stored in the org.hibernate.cache.internal.StandardQueryCache region. We can specify the expiration and eviction policies for this region. Also, if required, we can set a different region for a particular query to cache by using the query hint org.hibernate.cacheRegion.
• Hibernate keeps last update timestamps in a region named org.hibernate.cache.spi.UpdateTimestampsCache for all query cached tables. Hibernate uses this to verify that cached query results are not stale. It is best to turn off automatic eviction and expiration for this cache region, because entries in this cache must not be evicted/expired, as long as there are cached query results in cache results regions.