实体框架嵌套投影很慢

Question

我正在运行查询来获取用户配置文件。查询获取用户的详细信息，以及他们发布的所有评论，以及评论中的评论。

这很可能是我试图找回太多的情况，但是随着api从移动设备被呼叫，我宁愿尽可能地在一个网络呼叫中获得，而不是在多个网络中调用。

目前这是生成一些非常长的SQL，并需要大约25秒！

，关于如何提高它的任何提示，或者是否预测是连做它用每LINQ查询一个很大的SQL查询的

public UserVM GetUserInfo(string userId, string currentUserId) 
{ 
    var results = 
     from u in context.AspNetUsers 
     where u.Id == userId 
     select new UserVM 
     { 
      Name = u.UserName, Id = u.Id, ProfilePic = u.ProfilePicUrl, FollowerCount = u.Followers.Count, FollowingCount = u.Following.Count, 
      MemberSince = u.RegisteredDate, 
      RatingsCount = u.Ratings.Count(x => x.IsDeleted!=true), 
      FollowedByCurrentUser = currentUserId != null && u.Followers.Any(x => x.FollowedByUserId == currentUserId && x.UserId == userId), 
      reviews = 
       from r in u.Ratings 
       where r.IsDeleted != true 
       && r.IsDraft != true 

       select new RatingVM() 
       { 
        ratingId = r.Id, 
        author_name = r.User.UserName, 
        userId = r.UserId, 
        profile_photo_url = r.User.ProfilePicUrl, 
        rating = r.RatingValue, 
        text = r.RatingComment, 
        created = r.Created, 
        likeCount = r.RatingLikes.Count(x => x.IsLiked && x.RatingId == r.Id), 
        likedByCurrentUser = currentUserId != null && r.RatingLikes.Any(x => x.IsLiked && x.RatingId == r.Id && x.UserId == currentUserId), 
        photos = from ri in r.RatingImages 
          select new PhotoVM { Id = ri.Id, width = 0, height = 0, photo_reference = ri.PhotoUrl, isMember = true, googlePlaceId = r.Place.GooglePlaceId, placeName = r.Place.Name }, 
        comments = from c in r.Comments 
           where c.IsDeleted != true 
           select new CommentVM { commentId = c.Id, Created = c.Created, CommentText = c.CommentText, RatingId = r.Id , UserName = c.User.UserName, ProfilePicUrl = c.User.ProfilePicUrl, userId = c.UserId } 
       } 
     }; 

    return results.FirstOrDefault(); 
} 



SELECT 
[Project17].[C1] AS [C1], 
[Project17].[UserName] AS [UserName], 
[Project17].[Id] AS [Id], 
[Project17].[ProfilePicUrl] AS [ProfilePicUrl], 
[Project17].[C32] AS [C2], 
[Project17].[C33] AS [C3], 
[Project17].[RegisteredDate] AS [RegisteredDate], 
[Project17].[C34] AS [C4], 
[Project17].[C2] AS [C5], 
[Project17].[C31] AS [C6], 
[Project17].[C4] AS [C7], 
[Project17].[C5] AS [C8], 
[Project17].[C6] AS [C9], 
[Project17].[C7] AS [C10], 
[Project17].[C8] AS [C11], 
[Project17].[C9] AS [C12], 
[Project17].[C10] AS [C13], 
[Project17].[C11] AS [C14], 
[Project17].[C12] AS [C15], 
[Project17].[C13] AS [C16], 
[Project17].[C14] AS [C17], 
[Project17].[C3] AS [C18], 
[Project17].[C15] AS [C19], 
[Project17].[C16] AS [C20], 
[Project17].[C17] AS [C21], 
[Project17].[C18] AS [C22], 
[Project17].[C19] AS [C23], 
[Project17].[C20] AS [C24], 
[Project17].[C21] AS [C25], 
[Project17].[C22] AS [C26], 
[Project17].[C23] AS [C27], 
[Project17].[C24] AS [C28], 
[Project17].[C25] AS [C29], 
[Project17].[C26] AS [C30], 
[Project17].[C27] AS [C31], 
[Project17].[C28] AS [C32], 
[Project17].[C29] AS [C33], 
[Project17].[C30] AS [C34] 
FROM (SELECT 
    [Limit1].[Id] AS [Id], 
    [Limit1].[UserName] AS [UserName], 
    [Limit1].[ProfilePicUrl] AS [ProfilePicUrl], 
    [Limit1].[RegisteredDate] AS [RegisteredDate], 
    [Limit1].[C1] AS [C1], 
    [Limit1].[C2] AS [C2], 
    [UnionAll1].[C1] AS [C3], 
    [UnionAll1].[Id] AS [C4], 
    [UnionAll1].[Id1] AS [C5], 
    [UnionAll1].[C2] AS [C6], 
    [UnionAll1].[C3] AS [C7], 
    [UnionAll1].[UserId] AS [C8], 
    [UnionAll1].[C4] AS [C9], 
    [UnionAll1].[RatingValue] AS [C10], 
    [UnionAll1].[RatingComment] AS [C11], 
    [UnionAll1].[Created] AS [C12], 
    [UnionAll1].[C5] AS [C13], 
    [UnionAll1].[C6] AS [C14], 
    [UnionAll1].[Id2] AS [C15], 
    [UnionAll1].[Id3] AS [C16], 
    [UnionAll1].[C7] AS [C17], 
    [UnionAll1].[C8] AS [C18], 
    [UnionAll1].[PhotoUrl] AS [C19], 
    [UnionAll1].[C9] AS [C20], 
    [UnionAll1].[GooglePlaceId] AS [C21], 
    [UnionAll1].[Name] AS [C22], 
    [UnionAll1].[C10] AS [C23], 
    [UnionAll1].[C11] AS [C24], 
    [UnionAll1].[C12] AS [C25], 
    [UnionAll1].[C13] AS [C26], 
    [UnionAll1].[C14] AS [C27], 
    [UnionAll1].[C15] AS [C28], 
    [UnionAll1].[C16] AS [C29], 
    [UnionAll1].[C17] AS [C30], 
    CASE WHEN ([UnionAll1].[Id] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C31], 
    [Limit1].[C3] AS [C32], 
    [Limit1].[C4] AS [C33], 
    [Limit1].[C5] AS [C34] 
    FROM (SELECT TOP (1) 
     @p__linq__4 AS [p__linq__4], 
     @p__linq__5 AS [p__linq__5], 
     [Project3].[Id] AS [Id], 
     [Project3].[UserName] AS [UserName], 
     [Project3].[ProfilePicUrl] AS [ProfilePicUrl], 
     [Project3].[RegisteredDate] AS [RegisteredDate], 
     1 AS [C1], 
     CASE WHEN ((@p__linq__1 IS NOT NULL) AND (EXISTS (SELECT 
      1 AS [C1] 
      FROM [dbo].[Followers] AS [Extent5] 
      WHERE ([Project3].[Id] = [Extent5].[UserId]) AND ([Extent5].[FollowedByUserId] = @p__linq__2) AND ([Extent5].[UserId] = @p__linq__3) 
     ))) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C2], 
     [Project3].[C1] AS [C3], 
     [Project3].[C2] AS [C4], 
     [Project3].[C3] AS [C5] 
     FROM (SELECT 
      [Project2].[Id] AS [Id], 
      [Project2].[UserName] AS [UserName], 
      [Project2].[ProfilePicUrl] AS [ProfilePicUrl], 
      [Project2].[RegisteredDate] AS [RegisteredDate], 
      [Project2].[C1] AS [C1], 
      [Project2].[C2] AS [C2], 
      (SELECT 
       COUNT(1) AS [A1] 
       FROM [dbo].[Ratings] AS [Extent4] 
       WHERE ([Project2].[Id] = [Extent4].[UserId]) AND (1 <> [Extent4].[IsDeleted])) AS [C3] 
      FROM (SELECT 
       [Project1].[Id] AS [Id], 
       [Project1].[UserName] AS [UserName], 
       [Project1].[ProfilePicUrl] AS [ProfilePicUrl], 
       [Project1].[RegisteredDate] AS [RegisteredDate], 
       [Project1].[C1] AS [C1], 
       (SELECT 
        COUNT(1) AS [A1] 
        FROM [dbo].[Followers] AS [Extent3] 
        WHERE [Project1].[Id] = [Extent3].[FollowedByUserId]) AS [C2] 
       FROM (SELECT 
        [Extent1].[Id] AS [Id], 
        [Extent1].[UserName] AS [UserName], 
        [Extent1].[ProfilePicUrl] AS [ProfilePicUrl], 
        [Extent1].[RegisteredDate] AS [RegisteredDate], 
        (SELECT 
         COUNT(1) AS [A1] 
         FROM [dbo].[Followers] AS [Extent2] 
         WHERE [Extent1].[Id] = [Extent2].[UserId]) AS [C1] 
        FROM [dbo].[AspNetUsers] AS [Extent1] 
        WHERE [Extent1].[Id] = @p__linq__0 
       ) AS [Project1] 
      ) AS [Project2] 
     ) AS [Project3]) AS [Limit1] 
    OUTER APPLY (SELECT 
     CASE WHEN ([Filter10].[Id1] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1], 
     [Project9].[Id] AS [Id], 
     [Project9].[Id] AS [Id1], 
     [Project9].[C1] AS [C2], 
     [Project9].[C2] AS [C3], 
     [Project9].[UserId] AS [UserId], 
     [Project9].[C3] AS [C4], 
     [Project9].[RatingValue] AS [RatingValue], 
     [Project9].[RatingComment] AS [RatingComment], 
     [Project9].[Created] AS [Created], 
     [Project9].[C5] AS [C5], 
     [Project9].[C4] AS [C6], 
     [Filter10].[Id1] AS [Id2], 
     [Filter10].[Id1] AS [Id3], 
     CASE WHEN ([Filter10].[Id1] IS NULL) THEN CAST(NULL AS int) ELSE 0 END AS [C7], 
     CASE WHEN ([Filter10].[Id1] IS NULL) THEN CAST(NULL AS int) ELSE 0 END AS [C8], 
     [Filter10].[PhotoUrl] AS [PhotoUrl], 
     CASE WHEN ([Filter10].[Id1] IS NULL) THEN CAST(NULL AS bit) ELSE cast(1 as bit) END AS [C9], 
     [Filter10].[GooglePlaceId] AS [GooglePlaceId], 
     [Filter10].[Name] AS [Name], 
     CAST(NULL AS int) AS [C10], 
     CAST(NULL AS int) AS [C11], 
     CAST(NULL AS datetime2) AS [C12], 
     CAST(NULL AS varchar(1)) AS [C13], 
     CAST(NULL AS int) AS [C14], 
     CAST(NULL AS varchar(1)) AS [C15], 
     CAST(NULL AS varchar(1)) AS [C16], 
     CAST(NULL AS varchar(1)) AS [C17] 
     FROM (SELECT 
      [Project7].[Id] AS [Id], 
      [Project7].[RatingValue] AS [RatingValue], 
      [Project7].[RatingComment] AS [RatingComment], 
      [Project7].[Created] AS [Created], 
      [Project7].[PlaceId] AS [PlaceId], 
      [Project7].[UserId] AS [UserId], 
      [Limit1].[UserName] AS [C1], 
      N'' AS [C2], 
      [Limit1].[ProfilePicUrl] AS [C3], 
      CASE WHEN ((@p__linq__4 IS NOT NULL) AND (EXISTS (SELECT 
       1 AS [C1] 
       FROM [dbo].[RatingLikes] AS [Extent8] 
       WHERE ([Project7].[Id] = [Extent8].[RatingId]) AND ([Extent8].[IsLiked] = 1) AND ([Extent8].[RatingId] = [Project7].[Id]) AND ([Extent8].[UserId] = @p__linq__5) 
      ))) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C4], 
      [Project7].[C1] AS [C5] 
      FROM (SELECT 
       [Project6].[Id] AS [Id], 
       [Project6].[RatingValue] AS [RatingValue], 
       [Project6].[RatingComment] AS [RatingComment], 
       [Project6].[Created] AS [Created], 
       [Project6].[PlaceId] AS [PlaceId], 
       [Project6].[UserId] AS [UserId], 
       (SELECT 
        COUNT(1) AS [A1] 
        FROM [dbo].[RatingLikes] AS [Extent7] 
        WHERE ([Project6].[Id] = [Extent7].[RatingId]) AND ([Extent7].[IsLiked] = 1) AND ([Extent7].[RatingId] = [Project6].[Id])) AS [C1] 
       FROM (SELECT 
        [Extent6].[Id] AS [Id], 
        [Extent6].[RatingValue] AS [RatingValue], 
        [Extent6].[RatingComment] AS [RatingComment], 
        [Extent6].[Created] AS [Created], 
        [Extent6].[PlaceId] AS [PlaceId], 
        [Extent6].[UserId] AS [UserId] 
        FROM [dbo].[Ratings] AS [Extent6] 
        WHERE ([Limit1].[Id] = [Extent6].[UserId]) AND (1 <> [Extent6].[IsDeleted]) AND (1 <> [Extent6].[IsDraft]) 
       ) AS [Project6] 
      ) AS [Project7]) AS [Project9] 
     OUTER APPLY (SELECT [Extent9].[Id] AS [Id1], [Extent9].[PhotoUrl] AS [PhotoUrl], [Project10].[Name] AS [Name], [Project10].[GooglePlaceId] AS [GooglePlaceId] 
      FROM [dbo].[RatingImages] AS [Extent9] 
      LEFT OUTER JOIN (SELECT 
       [Extent10].[Id] AS [Id], 
       [Extent10].[Name] AS [Name], 
       [Extent10].[GooglePlaceId] AS [GooglePlaceId] 
       FROM [dbo].[Places] AS [Extent10] 
       WHERE [Project9].[PlaceId] = [Extent10].[Id]) AS [Project10] ON 1 = 1 
      WHERE [Project9].[Id] = [Extent9].[RatingId]) AS [Filter10] 
    UNION ALL 
     SELECT 
     2 AS [C1], 
     [Project15].[Id] AS [Id], 
     [Project15].[Id] AS [Id1], 
     [Project15].[C1] AS [C2], 
     [Project15].[C2] AS [C3], 
     [Project15].[UserId] AS [UserId], 
     [Project15].[C3] AS [C4], 
     [Project15].[RatingValue] AS [RatingValue], 
     [Project15].[RatingComment] AS [RatingComment], 
     [Project15].[Created] AS [Created], 
     [Project15].[C5] AS [C5], 
     [Project15].[C4] AS [C6], 
     CAST(NULL AS int) AS [C7], 
     CAST(NULL AS int) AS [C8], 
     CAST(NULL AS int) AS [C9], 
     CAST(NULL AS int) AS [C10], 
     CAST(NULL AS varchar(1)) AS [C11], 
     CAST(NULL AS bit) AS [C12], 
     CAST(NULL AS varchar(1)) AS [C13], 
     CAST(NULL AS varchar(1)) AS [C14], 
     [Join2].[Id2] AS [Id2], 
     [Join2].[Id2] AS [Id3], 
     [Join2].[Created] AS [Created1], 
     [Join2].[CommentText] AS [CommentText], 
     [Project15].[Id] AS [Id4], 
     [Join2].[UserName] AS [UserName], 
     [Join2].[ProfilePicUrl] AS [ProfilePicUrl], 
     [Join2].[UserId] AS [UserId1] 
     FROM (SELECT 
      [Project13].[Id] AS [Id], 
      [Project13].[RatingValue] AS [RatingValue], 
      [Project13].[RatingComment] AS [RatingComment], 
      [Project13].[Created] AS [Created], 
      [Project13].[UserId] AS [UserId], 
      [Limit1].[UserName] AS [C1], 
      N'' AS [C2], 
      [Limit1].[ProfilePicUrl] AS [C3], 
      CASE WHEN ((@p__linq__4 IS NOT NULL) AND (EXISTS (SELECT 
       1 AS [C1] 
       FROM [dbo].[RatingLikes] AS [Extent13] 
       WHERE ([Project13].[Id] = [Extent13].[RatingId]) AND ([Extent13].[IsLiked] = 1) AND ([Extent13].[RatingId] = [Project13].[Id]) AND ([Extent13].[UserId] = @p__linq__5) 
      ))) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C4], 
      [Project13].[C1] AS [C5] 
      FROM (SELECT 
       [Project12].[Id] AS [Id], 
       [Project12].[RatingValue] AS [RatingValue], 
       [Project12].[RatingComment] AS [RatingComment], 
       [Project12].[Created] AS [Created], 
       [Project12].[UserId] AS [UserId], 
       (SELECT 
        COUNT(1) AS [A1] 
        FROM [dbo].[RatingLikes] AS [Extent12] 
        WHERE ([Project12].[Id] = [Extent12].[RatingId]) AND ([Extent12].[IsLiked] = 1) AND ([Extent12].[RatingId] = [Project12].[Id])) AS [C1] 
       FROM (SELECT 
        [Extent11].[Id] AS [Id], 
        [Extent11].[RatingValue] AS [RatingValue], 
        [Extent11].[RatingComment] AS [RatingComment], 
        [Extent11].[Created] AS [Created], 
        [Extent11].[UserId] AS [UserId] 
        FROM [dbo].[Ratings] AS [Extent11] 
        WHERE ([Limit1].[Id] = [Extent11].[UserId]) AND (1 <> [Extent11].[IsDeleted]) AND (1 <> [Extent11].[IsDraft]) 
       ) AS [Project12] 
      ) AS [Project13]) AS [Project15] 
     INNER JOIN (SELECT [Extent14].[Id] AS [Id2], [Extent14].[CommentText] AS [CommentText], [Extent14].[Created] AS [Created], [Extent14].[RatingId] AS [RatingId], [Extent14].[IsDeleted] AS [IsDeleted], [Extent14].[UserId] AS [UserId], [Extent15].[UserName] AS [UserName], [Extent15].[ProfilePicUrl] AS [ProfilePicUrl] 
      FROM [dbo].[Comments] AS [Extent14] 
      INNER JOIN [dbo].[AspNetUsers] AS [Extent15] ON [Extent14].[UserId] = [Extent15].[Id]) AS [Join2] ON ([Project15].[Id] = [Join2].[RatingId]) AND (1 <> [Join2].[IsDeleted])) AS [UnionAll1] 
) AS [Project17] 
ORDER BY [Project17].[Id] ASC, [Project17].[C31] ASC, [Project17].[C5] ASC, [Project17].[C3] ASC 

Answer 1

EF6的加载策略正确的方法是不是最佳的加载复杂的对象图。还有其他几种方法来加载图形。

例如，您可以加载根AspNetUser实体，然后遍历导航属性来构建图形。 EF会根据需要延迟加载。一旦一个实体被缓存在上下文中，后续的导航就不会引起额外的查询。

事实上，如果您预取部分或全部相关实体，EF将“缝合”或“修复”您的导航属性。

因此，作为一种优化，您可以编写查询，使用一些简单而便宜的查询来获取您需要的实体。

像

var user = context.AspNetUsers.Where(u => u.Id == userId).Single(); 
var followers = context.Followers.Where(f => f.UserId == userId).ToList(); 
var ratings = context.Ratings.Where(f => f.UserId == userId).ToList(); 
var ratingIds = ratings.Select(r => r.Id).ToList(); 
var ratingLikes = context.RatingLikes.Where(x => ratingIds.Contains(x.RatingId) && x.IsLiked).ToList(); 
var ratingPhotos = context.RatingPhotos.Where(x => ratingIds.Contains(x.RatingId)).ToList(); 

然后建立从负载AspNetUser你的结果，例如

var u = user; 
    var results = 
       select new UserVM 
        { 
         Name = u.UserName, 
         Id = u.Id, 
         ProfilePic = u.ProfilePicUrl, 
         FollowerCount = u.Followers.Count, . . .