Isuru Samaraweera wrote: "JPA render code that requires extensive SQL tuning when it comes to legacy databases"?
In my opinion this might be true because legacy sql code is written to gain maximum performance.And if you use JPA to use OO modelling
performance will be compromised and JPQL generated might be extravagantly slow.
You'd have to tune the JPSQL as well. Which is a pain compared to "normal" SQL because you have less control. But yes, an awkwardly designed database isn't going to map well to a JPA model.
I tend to use JPA for simple one to one mappings so this isn't a major issue.