Hi everyone!

I have a Set<Event> in a persistent object. Is there a way to let only the last 50 Events to be loaded? I have a whole mess of them, and loading all of those would be a bit too slow.

I see there's Criteria.setMaxResults and the "where" attribute for Set. But what I don't know is how to apply criterias to Sets, or how to select only the last X elements instead of the first ones.

Any advice?

Thanks in advice!

You could always use 'order by' on whatever your field is that determines the last entries and sort desc instead of the default asc. Then if you take the first 50 entries you are effectively taking the most recently added ones (ie. the last 50 entries).

Either that or you'd have to do something where you get a count of the rows in the table and then just start from count - 50 when you get results back (this is the more yucky one though).

egregory

Hmm, the documentation said that this feature is only for Java 1.4. I'm using 1.5, so I thought I wouldn't be able to use it. But maybe it should read "Java 1.4 or later".

Still, I don't know how to set the 50 row limit for the <Set>...

criteria.setMaxResults(50)
should do it.

Clarification: you can set the max results on the query itself but not on the Set.

Well, I'm a total newbie in Hibernate, so this may sound stupid - but it's Hibernate that loads the <Set> for me, right? I don't know how to control that...

Ahh I see, misread the original question sort of. You have an Entity that has a Set<Event> in it and only want to load 50 of what the set contains. As far as I know it's an all or nothing proposition if you have a Set in an Entity. ie. you can eager/lazy load, but not only load part of a Set.

Oh, that's unfortunate. I guess I'll have to figure out how to do this manually (using HQL or something)...

Depending on the database you are using, you can use the where attribute of the set node to limit the results. For instance in Oracle:

There's no rownum in MySQL, which I'm using. Is there a workaround?