13.2. Improving entity performance

Many would agree that the persistence tier remains the primary suspect of most performance issues. Sometimes this is due to poor design or a failure to understand the technologies in play and how they interact. Sometimes it can be due to a weak vendor implementation or tool, or insufficient training on how to use the tool properly the way it was intended. Yet another cause can be not getting your database team involved during the design process. Your DBAs should have intimate knowledge of the data and database server(s), and be able to give you some insight on how best to interact with it, as well as be able to make modifications that your application could benefit from.

Our own experience has shown that the response time of applications will improve from 2 to 10 times simply by tuning the data access layer. When you are experiencing unacceptable performance, there might be several reasons to suspect this layer. For instance, the SQL statements are generated by the persistence provider, and unless you know how the persistence provider generates the SQL statement, you put the blame on the JPA provider!