Avoiding SELECT+1 when working with discriminators - nhibernate

Question

I'm using discriminators to deal with item states. I'm using the NHibernate Profiler and noticing that my application is going quite bonkers over selecting my states. I have 8 states in total and NHibernate keeps querying like so:
SELECT state0_.State_id as State1_10_0_,
state0_.Name as Name10_0_
FROM States state0_
WHERE state0_.State_id = **3** /* #p0 */
What triggers this SELECT+1 is when I select all items where the state is for example equal to 1, 2, 3, 4 or 5. This would issue one query for my items as well 5 queries for each state. Since I'm querying for items (with state) very often I'm executing an awful lot of queries.
Now, looking at the profiler I'm not sure it's much of an issue because the first state I query takes 6ms to query and 6ms to materialize. All other states display as being taken 0ms to query and 0ms to materialize. NHibernate Profiler still displays this as the notorious SELECT+1 problem.
From my aggregate root mapping I have:
References(x => x.State)
.Not.Nullable()
.Not.LazyLoad();
For my state discriminator mapping I have:
Id(x => x.Id, "State_id").GeneratedBy.Assigned();
Map(x => x.Name).Not.Nullable();
DiscriminateSubClassesOnColumn("State_id");
Is there something I'm not understanding regarding discriminators?
Here is the query causing trouble:
var items =
session.QueryOver(() => itemAlias)
.SelectList(x => x
.Select(xx => xx.Id).WithAlias(() => sentTo.Id)
.Select(xx => xx.State).WithAlias(() => sentTo.State)
.Select(xx => xx.Status).WithAlias(() => sentTo.Status)
)
.JoinAlias(() => itemAlias.State, () => stateAlias)
.WhereRestrictionOn(() => stateAlias.Id).IsInG(filters)
.Where(() => itemAlias.Status == Status.InProgress)
.TransformUsing(Transformers.AliasToBean<SentToDto>())
.List<SentToDto>();
Solution
The culprit was
.WhereRestrictionOn(() => stateAlias.Id).IsInG(filters)
To resolve my SELECT+1 issue I simply need to query by a list of discriminator objects instead of individual id's.
.Where(() => itemAlias.State.IsIn(new []{State.FooState, State.BarState}))

Answer 1

It sounds like you eager load the states themselves, so your first query is something like:
SELECT * FROM Items where StateID IN (1,2,3,4,5)
And then you have five queries one for each state:
SELECT Name FROM State WHERE StateID = 1
SELECT Name FROM State WHERE StateID = 2
....
It does that to eager load the name of the state, so to avoid it you should in your first query specify a join from your "items" to the "states" so you get the name there, otherwise set the State object to be lazy loaded if you don't need other info than the identifier in your result.