Seems that there is still not much resource on Java Persistence, which is included in EJB3. If I want to learn more about EJB-QL, the only way is to look at the resources of EJB2.1. The articles may not be updated, but most of the contents still apply.
However, I found one EJB-QL that is in the spec. seems not supported by most of the vendors, which is OFFSET and LIMIT. I found some articles on people asking Sun about the issue, but no one answers. Then I do a search on Google, and only found Resin which supports it.
These keywords are used together to limit the number of entity instances returned in a list, especially useful for entity storing up to ten thousand records. Your memory size must be a main issue by then. Actually, it is just similar to the ROWNUM functions provided by Oracle, but don’t know why so few vendors implement such a useful function.
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