NHibernate 3.1.0.4000 QueryOver SQL Optimisation

I have Entity 'Content'. Each Content has a 'Placement' property. Placement has a many-to-many relationship width 'AdType' entity (Placement has IList<\AdType> property mapped).

I need to load all Placements that are used at least in one Content and associated width specified AdType.

My DAL function looks like this:

    public IList<Placement> Load(AdType adType)
    {
        return NHibernateSession.QueryOver<Content>()
            .JoinQueryOver(content => content.Placement)
            .JoinQueryOver<AdType>(placement => placement.AdTypes)
            .Where(_adType => _adType.Id == adType.Id)
            .Select(x => x.Placement).List<Placement>();
    }

This works fine but when I look to the SQL log i see:

SELECT this_.PlacementId as y0_ FROM AdManager.dbo.[Content] this_ inner join AdManager.dbo.[Placement] placement1_ on this_.PlacementId=placement1_.PlacementId inner join AdManager.dbo.AdTypeToPlacement adtypes5_ on placement1_.PlacementId=adtypes5_.PlacementId inner join AdManager.dbo.[AdType] adtype2_ on adtypes5_.AdTypeId=adtype2_.AdTypeId WHERE adtype2_.AdTypeId = @p0

SELECT placement0_.PlacementId as Placemen1_26_0_, placement0_.Name as Name26_0_ FROM AdManager.dbo.[Placement] placement0_ WHERE placement0_.PlacementId=@p0

SELECT placement0_.PlacementId as Placemen1_26_0_开发者_开发知识库, placement0_.Name as Name26_0_ FROM AdManager.dbo.[Placement] placement0_ WHERE placement0_.PlacementId=@p0

This means that NHibernate takes all placements Id in first query and then queries all fields from Placement table by Id.

My question is: Does enyone know how to modify QueryOver method to force NHibernate load data in one query?

it seems NHibernate does think there might be something in the where which maybe filters out data which is needed tro initialize the placement. You can go with a subquery:

public IList<Placement> Load(AdType adType)
{
    var subquery = QueryOver.For<Content>()
        .JoinQueryOver(content => content.Placement)
        .JoinQueryOver<AdType>(placement => placement.AdTypes)
        .Where(_adType => _adType.Id == adType.Id)
        .Select(x => x.Id);

    return NHibernateSession.QueryOver<Content>()
        .WithSubquery.Where(content => content.Id).IsIn(subquery))
        //.Fetch(x => x.Placement).Eager   try with and without
        .Select(x => x.Placement).List<Placement>();
}

or SQL (has the disadvantage that it just fills the new Placement but doest track it)

public IList<Placement> Load(AdType adType)
{
    return NHibernateSession.CreateSQLQuery("SELECT p.Name as Name, ... FROM content c join placement p...")
        .SetResultTransformer(Transformers.AliastoBean<Placement>())
        .List<Placement>();
}