Gavin King

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since Aug 31, 2004
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Recent posts by Gavin King

Data modelling is outside the scope of ORM. However, Hibernate can be used to export DDL given existing mapping files. The generated schemas are very useable, as long as you add sufficient information about required constraints and indexes.
Berkeley DB is not a relational database, so no.
We will support cloudscape as soon as the new opensource version ("Derby") is released by Apache.
Ah looks like you noticed a little bug. This occurs only if you have a session that never uses the JDBC connection (not even to commit the transaction) which would never occur in practice.

Its a trivial fix.
Hum, Scott, I think some of the people promoting POJO persistence and ORM are actually not very big fans of UML ;-)

I agree that it would be nice to at least agree on *names* for things.
(1) Hibernate issues an update statement like


(2) Hibernate checks the JDBC row count, and throws a StaleObjectStateException if no rows were updated
Lots of people use Hibernate inside WebLogic, there is no problem with this combination ;-)
You don't need to use {aliases} for the tables you are not returning from the query. So your code can be very much simplified, and then it will work ;-) Nice when that happens :-)
We don't cover integration with *specific* application frameworks, however we cover principles that are common to all.
Each Hibernate session works with a distinct set of persistent instances.
Basically, there is no really efficient way to handle very deep table-per-subclass mappings in ORM. So we say try to avoid such deep inheritance hierarchies.

However, in Hibernate3, you can use a trick:

to handle your case (perhaps) more efficiently. There are tradeoffs between this approach and the <joined-subclass> approach. Usually <joined-subclass> is better, since it is less vulnerable to N+1 selects problems.
Yes, the query returns a List of ordered pairs of (Emp, Deptno) which Hibernate represents as Object[].
What I mean is that we implemented features that users asked for, instead of designing in a vacuum.
The memory acquired by your domain model objects is just a tiny fraction of the total memory usage of the server. Your JDBC driver, JSP engine, etc, are spewing out way more garbage than Hibernate is. So trying to control memory allocation by adjusting pool size for domain objects is unlikely to be very successful in real applications.
Well, no-one ever asked for it before