Hi...I've been using NHibernate in a large financial software for the past 6 month with great success. I must admit NH helped my team to move quickly forward and be "free" to design our object model without much concern for the DB....

But now we are at a performance bottleneck. Where are experimenting the n+1 select problem and other performance issues. I've been looking in the web and there are many options to fix this, 2 which are yet no implemented in the current release. These are batch-fetching and query caching.

The third option is doing eager fetching in some cases but unfortunately we have a few queries that we will not be able to optimize this way.

So I was wondering if there is a chance to make batch-fetching and query caching a priority in the 1.0 release. I believe performance is a critical missing part to make NH as strong as the Java counterpart.

Keep the good work!!

Sorry that I answer to your post, because it's just another question :oops: :

I also have major performance troubles with NHibernate, but I'm not sure if it's my fault, or something you just described. My problem is, that when flushing the session, NHibernates checks for all objects and their collections in the DB if they are still valid, also if I didn't changed the objects in the memory.

Is that what you ment, or did you know what I'm doing wrong?

Thanks so much and sorry for another question.
Rainer.

I believe Sergey is working on query caching at the moment and it can't be too far away

Cepheus: I dont think what your seeing is what is slowing you application. The checking of the collection has more to do in how you configured the cascade option in collections probably. Be sure to set them right.

paulh: I appologize. I just saw StandardQueryCache.cs on the latest CVS build. What I didnt see is the batch fetch which I believe is an easy solution to the n+1 problem.

I think batch fetch is a bit more tricky as it's not a concept supported by ADO.NET.

I have just finished porting both features from H2.1 so you can try grabbing a nightly build from http://www.renewtek.com/nhibernate/ccnet/default.aspx@_action_ViewFarmReport=true.html in a day or so. Batch fetching does not require any special support, as opposed to command batching which refers to batching INSERT/UPDATE/DELETE statements, and is not supported by ADO.NET.

Sergey..you're the man!