Is it possible in NHibernate to lock an entire table against read and writres. Basically I have a bidirectional 1-M relationship in which I need to query a table if the 1 side of the relationships exists and use it if it does. Otherwise, I want to create a new row in the table a use it subsequently.

thanks,
craig

No, it's not possible but you can obtain Connection from a session and use that to issue any commands you need.

Thanks Sergey,

Is there something specific in NHibernate that might help me achieve this in a different way?

thanks,
craig

If you set the connection isolation mode to Serializable, then most databases will acquire a read lock over the range of the values that you are querying over. That way, if you query again, you receive exactly the same set of values.

So, if the data is not there, no-one else will be permitted to commit a transaction that puts it there whilst your transaction is active.

Note that although Serializable is strictly correct, you can end up locking a large portion of the database out from other people so make sure that the transaction is as tight as possible.