Question

For a new project we are looking at NHibernate. We like it a lot overall, but one thing bothers us: it seems to be very resource consuming. Apparently NHibernate will load all the properties of an object even if you need only one of the properties. More over, it will do the same for the properties of child objects.

So we are weighing the pros and cons of NHibernate. What would you say they are, and if the upsides make up for the downsides?

Answer 1

Disadvantages:

1. It can take a while to get the hang of editing HBM files (although you could use Castle’s ActiveRecord, which does session management, and let’s you declare relationships with attributes, which it uses to generate HBM, since NH is underneath AR. Note: you don’t have to use the AR pattern with Castle’s AR).
2. It’s probably going to run more queries to retrieve a particular graph of data than you would if you wrote it by hand
3. It’s more difficult to make use of the power of the DB engine, since NH treats is like a dumb record store
4. Oracle support is not as good as other dialects.

Advantages

1. You can use Linq-to-NH, and use linq style queries against all the supported dialects.
2. You can use HQL instead of SQL
3. You can switch DBs venders with a couple lines in a config file
4. There are tools to generate your schema for you.
5. Support for versioning of instances