Hi,

First of all: THANKS A LOT FOR A FANTASTIC PRODUCT.

Now, my questions:

I have a rather large object graph which I have mapped successfully.

My question is: without setting lazy, will loading a root object load the entire graph? Or does it just fetch the first-level relations and then lazy-load the rest?

The object graph closure includes about 40 other classes (directly or indirectly) Will it try to join the entire thing?

What if my graph contains circular references?

Please tell me how Hibernate works without lazy.

many-to-ones are always loaded right away unless you use a lazy proxy.

one-to-many and many-to-many are loaded right away unless lazy=true.

so if you have lazy="false" on everything you will load the entire object graph as far as it can navigate from where you load.

OK, thanks. Is there a problem with having lazy="true" on all relations? I'm looking for the best defaults... (I generate the mapping file)

Davs Nick,

On the systems I've used hibernate with auto-generated mapping files I setted all to lazy, lazy, lazy + proxy ;)

Mainly because I had several access paths and query strategies for the data and thus I could not find a good way of defining what should be autoloaded or not....but that said, I would also consider going in a mark some of the stuff non-lazy simply because there aaalways is some stuff that needed to be loaded together - but that is dependent on the system and on your persistence/query strategies.

Mvh

Always lazy is what I would do.

Thanks for useful responses.

However, I'm still curious about how Hibernate deals with circular references. Is that different in the lazy and non-lazy cases?

Thanks again!!!

How about you let me worry about circular references. Thats the point.

That weren't nice answer Gavin ;)

nick - if you really want to now then look for the source ;)

(but I can tell you that to resolve such stuff it utilizes the session cache and some standard magick to do it - look for any decent ORM articles about this ;)

Gavin: I respect what you have done with Hibernate and that you have a lot of work to do, but don't be disrespectful. I actually find no answer to be way better than answers that makes me feel even more stupid than I am...

Yeah well, I know - I was feeling a bit frustrated this afternoon. I'm just not sure what a "nice" answer to "how does Hibernate handle circular references?" looks like.

You want me to completely explain the session level cache, two-phase load, disassembly/reassembly to and from the second-level cache, etc, etc? If you want to know, look at the code. The user shouldn't need to care, however.

sorry for being rude this time, all previous times, and all future times.....

Hum, can be in the faq ;-)

"You want me to completely explain the session level cache, two-phase load, disassembly/reassembly to and from the second-level cache, etc, etc? "

Hell no... saying "hibernate handles it for you" would suffice. I don't really care about the implementation - just tried to ask if I had to think about it when doing mapping, using the API, etc. Maybe my wording was wrong... hum, yes, obvisouly so.

"sorry for being rude this time, all previous times, and all future times....."

Sarcasm.... Fine.

I'm warning you about this grumpiness because I know of people who don't use JBoss because of Marc Fleury's way of handling people (on forums, mail lists and otherwise) It is easy to get put off.

So be careful.

/Nick

Actually it was not sarcasm.

And before you start with criticism of myself, Marc, or any one else, you should try to understand exactly how hard it is to handle the volume of user questions on this list, particularly when some people don't take the time to phrase questions properly (eg. asking "how does Hibernate handle circular references?" when all they really want to know is "Does Hibernate handle circular references?") or give enough information for me to be able to help. Yes, the forum actually comes with explicit instructions about what information to provide when you have a problem, but an enormous amount of the noise here consists of requests by those of us who answer questions for exactly that information. Guys it really doesnt take that much extra effort on your part to ask questions well - and it saves a lot of time for us.

Before I went fulltime on this, the forum traffic was absolutely killing me. You actually can't imagine how impossible it was to keep up. Now that its actually a paying job, I try to resolve to be much more patient and not get frustrated as often. Saying nothing is better than being rude. But, surprise, surprise, I am actually an imperfect human.

Now, I am grateful that too much success is our problem and certainly we can and do always continue to improve many things.

For example, Christian went to a lot of effort to give us a great new fully searchable forum, and I really hope that people will make use of this. I think the signal-to-noise has improved since we switched, so obviously some people are.

And finally, Nick, don't take this the wrong way, but no software vendor on earth, commercial or opensource would not have got a bit frustrated with you after your 95-questions-in-two-and-a-half-weeks marathon run, many of which were definitely stretching the limits of politeness in their own right.

I know its hard, but that's no excuse for responding like a 9 year old when he face a problem.

I've been one many heavy traffic lists and forums where the core members behave as they would if they met posters face to face. The Subversion and GLUE projects are excellent examples.

More often than not, however, forums and lists are driven by elitism and grumpiness. I hate that.

Still love your work, though :-)