用于Select N + 1的NHibernate QueryOver解决方案

Question

我遇到了我的多对多XML映射问题。最近我使用NHibernate Profiler并发现了这个Select N + 1问题。我似乎无法找到一个可行的解决方案，并且不知道我的映射是好还是与其查询有关。

场景：我有一个配置文件可以有多个预定义的标签。标签可以有父母和/或孩子。这些标签可以在许多配置文件中使用。我会告诉你我的相关类和映射。

Account.cs

public class Account 
{ 
    public int Id { get; set; } 
    public Profile Profile { get; set; } 
} 

Profile.cs

public class Profile 
{ 
    public int Id { get; set; } 
    public IList<ProfileTag> Tags { get; set; } 
} 

Profile.hbm.xml

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Agrolink.Application.Models" assembly="Agrolink.Application"> 
<class name="Agrolink.Application.Models.Profile" lazy="false" table="Profiles" > 

<id name="Id" column="Id" > 
    <generator class="identity" /> 
</id> 

<bag name="Tags" table="ProfileTags" cascade="all-delete-orphan" inverse="true"> 
    <key column="IdProfile" not-null="true"/> 
    <one-to-many class="Agrolink.Application.Models.ProfileTag" /> 
</bag> 

</class> 
</hibernate-mapping> 

ProfileTag.cs​​

public class ProfileTag 
{ 
    public int Id { get; set; } 

    public Profile Profile { get; set; } 

    public Tag Tag { get; set; } 
} 

ProfileTag.hbm.xml

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Agrolink.Application.Models" assembly="Agrolink.Application"> 
<class name="Agrolink.Application.Models.ProfileTag" lazy="false" table="ProfileTags" > 

<id name="Id" column="Id" > 
    <generator class="identity" /> 
</id> 

<many-to-one name="Profile" class="Agrolink.Application.Models.Profile" column="IdProfile" cascade="save-update" /> 
<many-to-one name="Tag" class="Agrolink.Application.Models.Tag" column="IdTag" cascade="none" /> 

</class> 
</hibernate-mapping> 

Tag.cs​​

public class Tag 
{ 
    public int Id { get; set; } 

    public Tag Parent { get; set; } 

    public IList<Tag> Children { get; set; } 
} 

Tag.hbm.xml

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Agrolink.Application.Models" assembly="Agrolink.Application"> 
<class name="Agrolink.Application.Models.Tag" lazy="false" table="Tags"> 

<id name="Id" column="Id" > 
    <generator class="identity" /> 
</id> 

<property name="Name" column="Name" /> 
<property name="Type" type="Agrolink.Application.Models.TagType, Agrolink.Application" column="IdType" /> 

<many-to-one name="Parent" class="Agrolink.Application.Models.Tag" column="IdParent" cascade="none" /> 

<bag name="Children" table="Tags" cascade="all" inverse="true"> 
    <key column="IdParent" not-null="true"/> 
    <one-to-many class="Agrolink.Application.Models.Tag" /> 
</bag> 

</class> 
</hibernate-mapping> 

当我QueryOver帐户我看到hes选择单独的所有标签。我怎样才能防止这一点？我尝试使用JoinAlias，但它没有任何区别。

我的地图可以和父母/孩子一起吗？

所有帮助表示赞赏！ Thx

Answer 1

将批量大小添加到Tag.hbm.xml中的Bag中。

<bag name="Children" table="Tags" cascade="all" inverse="true" batch-size="25"> 
    <key column="IdParent" not-null="true"/> 
    <one-to-many class="Agrolink.Application.Models.Tag" /> 
</bag>