Query Cache should not be allowed for queries having Non Cacheable Query Spaces.

Analysis:

• When query is cacheable i.e. 'org.hibernate.cacheable=true', and is having query spaces which are non cacheable, then this may lead to the well known 'N+1' issue.
• I.e. the cached query result containing the 'N' ids, will further result in N queries of 'findById' to the database.

Expectation:

• Query Cache should not be allowed for queries having Non Cacheable Query Spaces. Either throw an exception while loading the query, or rather ignore the query cache in this case.
• With this, even high number of puts to 'UpdateTimestampCache' can be avoided. Which are originating from all the high number of transactional DMLs being executed to a query space which is non-cacheable.

Possible Resolution: org.hibernate.loader.Loader.list method

• Maintain a set of cacheable 'query space (String)' - call it Metadata etc
• To the existing condition of checking whether cacheable or not, add the check of validating every corresponding query spaces in this Metadata set.
• If any of the query space is not in the cacheable metadata set, mark the final boolean variable 'cacheable' as false.
• So 'listIgnoreQueryCache' will be called rather than 'listUsingQueryCache'