I've written multiple articles here at Javalobby on the Hibernate O/R mapping tool, and they are usually met with a large degree of popularity. Hibernate isn't just a popular kid on the block, however; it is actually a very powerful, consistent, and reliable database mapping tool. Mapping between objects in Java to relational databases has many facets that you must be aware of. Hibernate does a particularly good job of making the process simple to start, and providing the facilities to allow it to scale well and meet exceedingly complex mapping demands.
One of the primary concerns of mappings between a database and your Java application is performance. One of the common concerns of people who haven't spent much time working with Hibernate in particular, is that O/R mapping tools will limit your ability to make performance-enhancing changes to particular queries and retrievals. Today I want to discuss two facets of the Hibernate infrastructure that are implemented to handle certain performance concerns - the second-level cache and the query cache...