NHibernate with Sql Azure and Sharding

Question

Does anyone have any good sources of information of using NHibernate with Sql Azure with the implications of sharding (because of the 10gb cap)? I know there are posts on the internet that reference a sharding project for NH but they are from 3rd quarter 09 and I haven't found any much more relevant on google.

Related does anyone have information about manually implementing sharding if the sharding project isn't viable to use yet? Would it just be as simple as creating a session factory for each shard and keep a collection of factories? That seems like it would be problematic reproducing the ISession calls through each factory however I suppose it could be achieved by passing operations as Funcs that get invoked on the ISession from each factory but seems more like the wrong path to be going down.

Answer 1

I wrote a proof of concept about a month ago using NHibernate on SQLAzure/Sharding. As you've pointed out, there are aspects that just do not feel right about it. Until the NH support has evolved, you may have to try a few things to find out what works best for you. I can tell you a general flow of how it worked for us.

We implemented a simple sharding strategy factory that provides strategies that decide which shard to place you in based on our needs. Your needs may vary here. The key is creating strategies that process, merge and order your query results. From there, session creation and usage is all the same as any other session usage, which is highly desirable.

EDIT: I know this post by Ayende is a few months old, but it's exactly how we implemented it and it works. The rumor is better support in nHibernate will be coming.