实体框架查询和性能
[英]entity framework query and performance
问题描述
我有一个像社交网络这样的项目，我必须写一个查询来获取一些帖子以及我的关注者（未被阻止）所喜欢的帖子的最后评论
public List<PostProject> GetFavoritePosts(string userId, int currentPage, int noOfRecords)
{
var skipPosts = noOfRecords * currentPage;
int i = -260;
var day = DateTime.Now.AddDays(i);
var blockedusers = DataContext.BlockedUsers.Where(bu => bu.BlockerId == userId);
var followers = DataContext.FollowUser.Where(u => u.FollowFromUserId == userId);
var posts = DataContext.Posts.Where(p => p.UserId != userId
&& p.DateOfUpdate > day
&& p.Likes.Any(l => followers.Any(fu => fu.FollowToUserId == l.UserId))
&& p.PostStatusId == 1
&& p.PostType == false
&& blockedusers.All(bu => bu.BlockedId != p.UserId));
var feed = posts
.OrderByDescending(post => post.Likes.Count)
.Select(post => new PostProject
{
PostId = post.PostId,
Content = post.Content,
Image = post.Image,
Location = post.Location,
Video = post.Video,
CreatedDate = post.CreatedDate,
DateOfUpdate = post.DateOfUpdate,
User = post.User,
ILiked = post.Likes.Any(like => like.UserId == userId),
LikeCount = post.Likes.Count,
CommentsCount = post.Comments.Count,
PostStatusId = post.PostStatusId,
ShareCount = post.SharePosts.Count,
Comments = new List<Comment> { post.Comments.OrderByDescending(c => c.CommentDate).FirstOrDefault() }
});
return feed.Skip(() => skipPosts).Take(() => noOfRecords).ToList();
}
这段代码生成带有16 select和50ms运行时间的sqlQuery !!!!
我的错在哪里谢谢
sql查询：
SELECT
[Project13].[PostStatusId] AS [PostStatusId],
[Project13].[PostId] AS [PostId],
[Project13].[Content] AS [Content],
[Project13].[Image] AS [Image],
[Project13].[Location] AS [Location],
[Project13].[Video] AS [Video],
[Project13].[CreatedDate] AS [CreatedDate],
[Project13].[DateOfUpdate] AS [DateOfUpdate],
[Project13].[Id] AS [Id],
[Project13].[VisualId] AS [VisualId],
[Project13].[ProfilePicUrl] AS [ProfilePicUrl],
[Project13].[DateCreated] AS [DateCreated],
[Project13].[Activated] AS [Activated],
[Project13].[ActivationCode] AS [ActivationCode],
[Project13].[RoleId] AS [RoleId],
[Project13].[TeamId] AS [TeamId],
[Project13].[RegisterToken] AS [RegisterToken],
[Project13].[Email] AS [Email],
[Project13].[EmailConfirmed] AS [EmailConfirmed],
[Project13].[PasswordHash] AS [PasswordHash],
[Project13].[SecurityStamp] AS [SecurityStamp],
[Project13].[PhoneNumber] AS [PhoneNumber],
[Project13].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project13].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project13].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project13].[LockoutEnabled] AS [LockoutEnabled],
[Project13].[AccessFailedCount] AS [AccessFailedCount],
[Project13].[UserName] AS [UserName],
[Project13].[C1] AS [C1],
[Project13].[C4] AS [C2],
[Project13].[C5] AS [C3],
[Project13].[C6] AS [C4],
[Project13].[C2] AS [C5],
[Project13].[CommentId] AS [CommentId],
[Project13].[CommentText] AS [CommentText],
[Project13].[PostId1] AS [PostId1],
[Project13].[CommentDate] AS [CommentDate],
[Project13].[UserId] AS [UserId],
[Project13].[RowVersion] AS [RowVersion]
FROM ( SELECT
[Project11].[PostId] AS [PostId],
[Project11].[Content] AS [Content],
[Project11].[PostStatusId] AS [PostStatusId],
[Project11].[Image] AS [Image],
[Project11].[Location] AS [Location],
[Project11].[Video] AS [Video],
[Project11].[CreatedDate] AS [CreatedDate],
[Project11].[DateOfUpdate] AS [DateOfUpdate],
[Project11].[Id] AS [Id],
[Project11].[VisualId] AS [VisualId],
[Project11].[ProfilePicUrl] AS [ProfilePicUrl],
[Project11].[DateCreated] AS [DateCreated],
[Project11].[Activated] AS [Activated],
[Project11].[ActivationCode] AS [ActivationCode],
[Project11].[RoleId] AS [RoleId],
[Project11].[TeamId] AS [TeamId],
[Project11].[RegisterToken] AS [RegisterToken],
[Project11].[Email] AS [Email],
[Project11].[EmailConfirmed] AS [EmailConfirmed],
[Project11].[PasswordHash] AS [PasswordHash],
[Project11].[SecurityStamp] AS [SecurityStamp],
[Project11].[PhoneNumber] AS [PhoneNumber],
[Project11].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project11].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project11].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project11].[LockoutEnabled] AS [LockoutEnabled],
[Project11].[AccessFailedCount] AS [AccessFailedCount],
[Project11].[UserName] AS [UserName],
[Project11].[C1] AS [C1],
[Limit1].[CommentId] AS [CommentId],
[Limit1].[CommentText] AS [CommentText],
[Limit1].[PostId] AS [PostId1],
[Limit1].[CommentDate] AS [CommentDate],
[Limit1].[UserId] AS [UserId],
[Limit1].[RowVersion] AS [RowVersion],
1 AS [C2],
[Project11].[C2] AS [C3],
[Project11].[C3] AS [C4],
[Project11].[C4] AS [C5],
[Project11].[C5] AS [C6]
FROM (SELECT
[Project9].[PostId] AS [PostId],
[Project9].[Content] AS [Content],
[Project9].[PostStatusId] AS [PostStatusId],
[Project9].[Image] AS [Image],
[Project9].[Location] AS [Location],
[Project9].[Video] AS [Video],
[Project9].[CreatedDate] AS [CreatedDate],
[Project9].[DateOfUpdate] AS [DateOfUpdate],
[Project9].[Id] AS [Id],
[Project9].[VisualId] AS [VisualId],
[Project9].[ProfilePicUrl] AS [ProfilePicUrl],
[Project9].[DateCreated] AS [DateCreated],
[Project9].[Activated] AS [Activated],
[Project9].[ActivationCode] AS [ActivationCode],
[Project9].[RoleId] AS [RoleId],
[Project9].[TeamId] AS [TeamId],
[Project9].[RegisterToken] AS [RegisterToken],
[Project9].[Email] AS [Email],
[Project9].[EmailConfirmed] AS [EmailConfirmed],
[Project9].[PasswordHash] AS [PasswordHash],
[Project9].[SecurityStamp] AS [SecurityStamp],
[Project9].[PhoneNumber] AS [PhoneNumber],
[Project9].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project9].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project9].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project9].[LockoutEnabled] AS [LockoutEnabled],
[Project9].[AccessFailedCount] AS [AccessFailedCount],
[Project9].[UserName] AS [UserName],
CASE WHEN ( EXISTS (SELECT
1 AS [C1]
FROM [dbo].[Likes] AS [Extent10]
WHERE ([Project9].[PostId] = [Extent10].[PostId]) AND (([Extent10].[UserId] = @p__linq__4) OR (([Extent10].[UserId] IS NULL) AND (@p__linq__4 IS NULL)))
)) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C1],
[Project9].[C1] AS [C2],
[Project9].[C2] AS [C3],
[Project9].[C3] AS [C4],
[Project9].[C4] AS [C5]
FROM ( SELECT
[Project8].[PostId] AS [PostId],
[Project8].[Content] AS [Content],
[Project8].[PostStatusId] AS [PostStatusId],
[Project8].[Image] AS [Image],
[Project8].[Location] AS [Location],
[Project8].[Video] AS [Video],
[Project8].[CreatedDate] AS [CreatedDate],
[Project8].[DateOfUpdate] AS [DateOfUpdate],
[Project8].[Id] AS [Id],
[Project8].[VisualId] AS [VisualId],
[Project8].[ProfilePicUrl] AS [ProfilePicUrl],
[Project8].[DateCreated] AS [DateCreated],
[Project8].[Activated] AS [Activated],
[Project8].[ActivationCode] AS [ActivationCode],
[Project8].[RoleId] AS [RoleId],
[Project8].[TeamId] AS [TeamId],
[Project8].[RegisterToken] AS [RegisterToken],
[Project8].[Email] AS [Email],
[Project8].[EmailConfirmed] AS [EmailConfirmed],
[Project8].[PasswordHash] AS [PasswordHash],
[Project8].[SecurityStamp] AS [SecurityStamp],
[Project8].[PhoneNumber] AS [PhoneNumber],
[Project8].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project8].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project8].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project8].[LockoutEnabled] AS [LockoutEnabled],
[Project8].[AccessFailedCount] AS [AccessFailedCount],
[Project8].[UserName] AS [UserName],
[Project8].[C1] AS [C1],
[Project8].[C2] AS [C2],
[Project8].[C3] AS [C3],
(SELECT
COUNT(1) AS [A1]
FROM [dbo].[SharePosts] AS [Extent9]
WHERE [Project8].[PostId] = [Extent9].[PostId]) AS [C4]
FROM ( SELECT
[Project7].[PostId] AS [PostId],
[Project7].[Content] AS [Content],
[Project7].[PostStatusId] AS [PostStatusId],
[Project7].[Image] AS [Image],
[Project7].[Location] AS [Location],
[Project7].[Video] AS [Video],
[Project7].[CreatedDate] AS [CreatedDate],
[Project7].[DateOfUpdate] AS [DateOfUpdate],
[Project7].[Id] AS [Id],
[Project7].[VisualId] AS [VisualId],
[Project7].[ProfilePicUrl] AS [ProfilePicUrl],
[Project7].[DateCreated] AS [DateCreated],
[Project7].[Activated] AS [Activated],
[Project7].[ActivationCode] AS [ActivationCode],
[Project7].[RoleId] AS [RoleId],
[Project7].[TeamId] AS [TeamId],
[Project7].[RegisterToken] AS [RegisterToken],
[Project7].[Email] AS [Email],
[Project7].[EmailConfirmed] AS [EmailConfirmed],
[Project7].[PasswordHash] AS [PasswordHash],
[Project7].[SecurityStamp] AS [SecurityStamp],
[Project7].[PhoneNumber] AS [PhoneNumber],
[Project7].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project7].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project7].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project7].[LockoutEnabled] AS [LockoutEnabled],
[Project7].[AccessFailedCount] AS [AccessFailedCount],
[Project7].[UserName] AS [UserName],
[Project7].[C1] AS [C1],
[Project7].[C2] AS [C2],
(SELECT
COUNT(1) AS [A1]
FROM [dbo].[Comments] AS [Extent8]
WHERE [Project7].[PostId] = [Extent8].[PostId]) AS [C3]
FROM ( SELECT
[Project6].[PostId] AS [PostId],
[Project6].[Content] AS [Content],
[Project6].[PostStatusId] AS [PostStatusId],
[Project6].[Image] AS [Image],
[Project6].[Location] AS [Location],
[Project6].[Video] AS [Video],
[Project6].[CreatedDate] AS [CreatedDate],
[Project6].[DateOfUpdate] AS [DateOfUpdate],
[Project6].[Id] AS [Id],
[Project6].[VisualId] AS [VisualId],
[Project6].[ProfilePicUrl] AS [ProfilePicUrl],
[Project6].[DateCreated] AS [DateCreated],
[Project6].[Activated] AS [Activated],
[Project6].[ActivationCode] AS [ActivationCode],
[Project6].[RoleId] AS [RoleId],
[Project6].[TeamId] AS [TeamId],
[Project6].[RegisterToken] AS [RegisterToken],
[Project6].[Email] AS [Email],
[Project6].[EmailConfirmed] AS [EmailConfirmed],
[Project6].[PasswordHash] AS [PasswordHash],
[Project6].[SecurityStamp] AS [SecurityStamp],
[Project6].[PhoneNumber] AS [PhoneNumber],
[Project6].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Project6].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Project6].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Project6].[LockoutEnabled] AS [LockoutEnabled],
[Project6].[AccessFailedCount] AS [AccessFailedCount],
[Project6].[UserName] AS [UserName],
[Project6].[C1] AS [C1],
(SELECT
COUNT(1) AS [A1]
FROM [dbo].[Likes] AS [Extent7]
WHERE [Project6].[PostId] = [Extent7].[PostId]) AS [C2]
FROM ( SELECT
[Project5].[PostId] AS [PostId],
[Project5].[Content] AS [Content],
[Project5].[PostStatusId] AS [PostStatusId],
[Project5].[Image] AS [Image],
[Project5].[Location] AS [Location],
[Project5].[Video] AS [Video],
[Project5].[CreatedDate] AS [CreatedDate],
[Project5].[DateOfUpdate] AS [DateOfUpdate],
[Extent6].[Id] AS [Id],
[Extent6].[VisualId] AS [VisualId],
[Extent6].[ProfilePicUrl] AS [ProfilePicUrl],
[Extent6].[DateCreated] AS [DateCreated],
[Extent6].[Activated] AS [Activated],
[Extent6].[ActivationCode] AS [ActivationCode],
[Extent6].[RoleId] AS [RoleId],
[Extent6].[TeamId] AS [TeamId],
[Extent6].[RegisterToken] AS [RegisterToken],
[Extent6].[Email] AS [Email],
[Extent6].[EmailConfirmed] AS [EmailConfirmed],
[Extent6].[PasswordHash] AS [PasswordHash],
[Extent6].[SecurityStamp] AS [SecurityStamp],
[Extent6].[PhoneNumber] AS [PhoneNumber],
[Extent6].[PhoneNumberConfirmed] AS [PhoneNumberConfirmed],
[Extent6].[TwoFactorEnabled] AS [TwoFactorEnabled],
[Extent6].[LockoutEndDateUtc] AS [LockoutEndDateUtc],
[Extent6].[LockoutEnabled] AS [LockoutEnabled],
[Extent6].[AccessFailedCount] AS [AccessFailedCount],
[Extent6].[UserName] AS [UserName],
[Project5].[C1] AS [C1]
FROM (SELECT
[Extent1].[PostId] AS [PostId],
[Extent1].[Content] AS [Content],
[Extent1].[PostStatusId] AS [PostStatusId],
[Extent1].[UserId] AS [UserId],
[Extent1].[Image] AS [Image],
[Extent1].[Location] AS [Location],
[Extent1].[Video] AS [Video],
[Extent1].[CreatedDate] AS [CreatedDate],
[Extent1].[DateOfUpdate] AS [DateOfUpdate],
(SELECT
COUNT(1) AS [A1]
FROM [dbo].[Likes] AS [Extent5]
WHERE [Extent1].[PostId] = [Extent5].[PostId]) AS [C1]
FROM [dbo].[Posts] AS [Extent1]
WHERE ( NOT (([Extent1].[UserId] = @p__linq__0) AND (0 = (CASE WHEN (@p__linq__0 IS NULL) THEN cast(1 as bit) ELSE cast(0 as bit) END)))) AND ([Extent1].[DateOfUpdate] > @p__linq__1) AND ( EXISTS (SELECT
1 AS [C1]
FROM ( SELECT
[Extent2].[UserId] AS [UserId]
FROM [dbo].[Likes] AS [Extent2]
WHERE [Extent1].[PostId] = [Extent2].[PostId]
) AS [Project1]
WHERE EXISTS (SELECT
1 AS [C1]
FROM [dbo].[FollowUsers] AS [Extent3]
WHERE ([Extent3].[FollowFromUserId] = @p__linq__2) AND ([Extent3].[FollowToUserId] = [Project1].[UserId])
)
)) AND (1 = [Extent1].[PostStatusId]) AND (0 = [Extent1].[PostType]) AND ( NOT EXISTS (SELECT
1 AS [C1]
FROM [dbo].[BlockedUsers] AS [Extent4]
WHERE ([Extent4].[BlockerId] = @p__linq__3) AND (([Extent4].[BlockedId] = [Extent1].[UserId]) OR (CASE WHEN ([Extent4].[BlockedId] <> [Extent1].[UserId]) THEN cast(1 as bit) WHEN ([Extent4].[BlockedId] = [Extent1].[UserId]) THEN cast(0 as bit) END IS NULL))
)) ) AS [Project5]
LEFT OUTER JOIN [dbo].[AspNetUsers] AS [Extent6] ON [Project5].[UserId] = [Extent6].[Id]
) AS [Project6]
) AS [Project7]
) AS [Project8]
) AS [Project9] ) AS [Project11]
OUTER APPLY (SELECT TOP (1) [Project12].[CommentId] AS [CommentId], [Project12].[CommentText] AS [CommentText], [Project12].[PostId] AS [PostId], [Project12].[CommentDate] AS [CommentDate], [Project12].[UserId] AS [UserId], [Project12].[RowVersion] AS [RowVersion]
FROM ( SELECT
[Extent11].[CommentId] AS [CommentId],
[Extent11].[CommentText] AS [CommentText],
[Extent11].[PostId] AS [PostId],
[Extent11].[CommentDate] AS [CommentDate],
[Extent11].[UserId] AS [UserId],
[Extent11].[RowVersion] AS [RowVersion]
FROM [dbo].[Comments] AS [Extent11]
WHERE [Project11].[PostId] = [Extent11].[PostId]
) AS [Project12]
ORDER BY [Project12].[CommentDate] DESC ) AS [Limit1]
) AS [Project13]
ORDER BY [Project13].[C3] DESC, [Project13].[PostId] ASC, [Project13].[Id] ASC, [Project13].[C2] ASC
2 个解决方案
解决方案1
1 2017-06-19 06:05:21
首先，Linq和Linq to SQL之间似乎存在混淆。 并非所有的Linq都可以转换为SQL查询。 例如： Any()和All()不能与Linq to Sql一起使用-它们是内存中的收集函数。 这意味着需要获取所有行，然后再解决。
您也没有解决前两个查询，例如，通过调用ToList() 。
var blockedusers = DataContext.BlockedUsers.Where(bu => bu.BlockerId == userId);
var followers = DataContext.FollowUser.Where(u => u.FollowFromUserId == userId);
这使它们每次使用时都可以按需运行（延迟查询执行），这意味着它们每次都调用SQL。 当心IEnumerable！
通过在同一查询中对BlockedUser和FollowUser进行联接，您可能会摆脱所有问题。 例如，对BlockedUser使用左联接，并通过测试被阻止的用户为空来消除这些行。
解决方案2
0 2017-06-19 06:09:14
我认为，您应该首先进行排序，跳过，获取然后选择新的PostObject作为回报
实体框架 6 - 查询性能
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