Hello.

I have a parent object with the list of the depending children objects (one-to-many)...After setting the list to null and updating the parent object nhibernate executes a delete statement for each single child object in the list. THis takes to long and it is a performance loss.

Is there any way to delete n children in a single statement????
(like: delete child where parent = 1)???

thanx for any reply.

markov

Does it help if you do list.Clear();? See http://www.hibernate.org/hib_docs/nhibernate/html/performance.html#performance-collections-oneshotdelete (although this reference suggests that your approach should work too).

list.Clear() deletes all children but still one by one....

any idea how to write it in standard SQL?

maybe
session.Delete("from object o where o.Parent.id=...")

btw. I think GeAr is right, just follow the link he provided. Or we misunderstand your problem.

your example still executes multiple delete statements.
like:
delete child where id = ....
delete child where id = ....
delete child where id = ....
delete child where id = ....

deleting 1000 childs takes about 10 seconds and one sigle query takes 0 seconds for the same result!

Hm that's strange. I didn't tested it but I'm sure I used "one shoot delete" without problems. Looks like some driver or dialect issue, btw. what db driver/dialect you are using?

As a workaround I can propose sth like this:
IDBConnection conn=session.Connection()
IDBCommand cmd=conn.CreateCommand()
cmd.CommandText="delete from table where idparent=...."
cmd.ExecuteNonQuery()

("hibernate.connection.provider" ,"NHibernate.Connection.DriverConnectionProvider");
("hibernate.dialect" ,"NHibernate.Dialect.MsSql2000Dialect");
("hibernate.connection.driver_class" ,"NHibernate.Driver.SqlClientDriver");