[hibernate-dev] Immutable entities read-only caching improvement proposal

Hi guys, Taking this comment as a starting point http://vladmihalcea.com/2015/04/27/how-does-hibernate-read_only-cacheconc... To reduce cache entities hydration, we could simply use the: "hibernate.cache.use_reference_entries" setting, but that's too restrictive as the AbstractEntityPersister prevents it when there are one-to-many associations on an immutable entity:     public boolean canUseReferenceCacheEntries() {         // todo : should really validate that the cache access type is read-only         if ( ! factory.getSettings().isDirectReferenceCacheEntriesEnabled() ) {             return false;         }         // for now, limit this to just entities that:         //         1) are immutable         if ( entityMetamodel.isMutable() ) {             return false;         }         //        2)  have no associations.  Eventually we want to be a little more lenient with associations.         for ( Type type : getSubclassPropertyTypeClosure() ) {             if ( type.isAssociationType() ) {                 return false;             }         }         return true;     } If the entity is immutable and all to-many associations are all marked with "(a)org.hibernate.annotations.Cache(usage = CacheConcurrencyStrategy.READ_ONLY)" we could allow the entity graph to be saved as an object reference. This way we can save a lot of unnecessary CPU processing, spent with hydrating each second-level cache entry. Vlad