Session.Get负载有N + 1甚至当懒惰=假

我有实体这样的：Session.Get负载有N + 1甚至当懒惰=假

public class User 
{ 
    public virtual int Id { get; set;} 
    public virtual Iesi.Collections.Generic.ISet<Character> Characters { get; set; } 
} 

public class Character 
{ 
    public virtual int Id { get; set;} 
    public virtual User User { get; set;} 
    public virtual Iesi.Collections.Generic.ISet<UserCharacterSmartChallengeTracker> SmartChallengeTrackers { get; set; } 
} 

public class UserCharacterSmartChallengeTracker 
{ 
    public virtual int Id { get; set; } 
    public virtual int? CharacterId { get; set; } 
}

他们都是不懒加载。

当我做session.Get<User>()我看到这样的疑问：

SELECT smartchall0_.character_id     as character3_1_, 
     smartchall0_.id        as id1_, 
     smartchall0_.id        as id51_0_, 
     smartchall0_.character_id     as character3_51_0_, 
FROM public.user_character_smart_challenge_trackers smartchall0_ 
WHERE smartchall0_.character_id = 48176 /* :p0 */ 

SELECT smartchall0_.character_id     as character3_1_, 
     smartchall0_.id        as id1_, 
     smartchall0_.id        as id51_0_, 
     smartchall0_.character_id     as character3_51_0_, 
FROM public.user_character_smart_challenge_trackers smartchall0_ 
WHERE smartchall0_.character_id = 48175 /* :p0 */ 

-- and others

我想所有这些预加载到会话缓存：

var ids = session.Query<Character>().Where(x => x.User.Id == id) 
      .Select(x => x.Id) 
      .ToArray(); 
session.Query<UserCharacterSmartChallengeTracker>().Where(x => ids.Contains(x.Id)).ToArray();

与查询

select character0_.id as col_0_0_ 
from public.characters character0_ 
where character0_.user_id = 9602 /* :p0 */ 
select usercharac0_.id        as id51_, 
     usercharac0_.character_id     as character3_5 
from public.user_character_smart_challenge_trackers usercharac0_ 
where usercharac0_.id in (48176 /* :p0 */, 48175 /* :p1 */, 48174 /* :p2 */, 48173 /* :p3 */, 
          48172 /* :p4 */, 48171 /* :p5 */, 48170 /* :p6 */, 48169 /* :p7 */)

但NHibernate的忽略了它们都已经加载到会话缓存并生成相同的事实N + 1个查询！如何解决这个问题？

更新：与

session.QueryOver<Character>().Where(x => x.User.Id == id) 
       .Fetch(x => x.User).Lazy 
       .Fetch(x=>x.SmartChallengeTrackers).Eager 
       .List();

预紧消除N + 1，但使NHibernate的负荷字符第二次，当我做session.Get<User>我想避免！

来源

2016-07-08 Vlad

你吃过一起来看看在这个文档中本节（http://nhibernate.info/doc/nh/en/index.html#performance-fetching-custom）？ –

我的理解是，预加载不会影响NH生成的查询，只是需要完全水合对象还是从第一级缓存中获取它们。 –

你真的想用session.Get ？为什么不写一个投影到某个对象的查询，以免每次都加载整个对象图？ – Fran

我用期货：

 var q = session.Query<User>().Where(x => x.Id == id); 

     var lst = new List<IEnumerable> 
     { 
      q.FetchMany(x => x.Characters).ToFuture(), 
      q.Fetch(x=>x.UpdateableData).ToFuture(), 
      session.QueryOver<User>().Where(x => x.Id == id) 
       .Fetch(x=>x.Characters).Eager 
       .Fetch(x => x.Characters.First().SmartChallengeTrackers).Eager 
       .Future() 
     }; 

     var r = session.QueryOver<User>().Where(x => x.Id == id) 
      .TransformUsing(Transformers.DistinctRootEntity) 
      .Future(); 

     foreach (IEnumerable el in lst) 
     { 
      foreach (object o in el) 
      { 

      } 
     } 

     return r.ToArray();

来源

2016-07-13 12:08:27 Vlad

Session.Get负载有N + 1甚至当懒惰=假

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