实体框架GroupBy到Sql生成

本文关键字：Sql 生成 GroupBy 框架 实体 | 更新日期: 2023-09-27 18:09:53

我坚持EF的性能问题。

        using (var context = new CustomDbContext())
        {
            var result = context.
                TransactionLines
                .Where(x => 
                    x.Transaction.TransactionTypeId == 1433 &&
                    (x.Transaction.Eob.EobBatchId == null || x.Transaction.Eob.EobBatch.Status == EobBatchStatusEnum.Completed)
                )
                .GroupBy(x => x.VisitLine.ProcedureId)
                .Select(x => new
                {
                    Id = x.Key,
                    PaidAmount = x.Sum(t => t.PaidAmount),
                    Code = context.Procedures.Where(h => h.Id == x.Key).Select(h => h.Code).FirstOrDefault()
                }).ToArray();
        }
EF生成下一个sql: 
SELECT 
1 AS [C1], 
[Project6].[ProcedureId] AS [ProcedureId], 
[Project6].[C2] AS [C2], 
[Project6].[C1] AS [C3]
FROM ( SELECT 
    [Project5].[ProcedureId] AS [ProcedureId], 
    [Project5].[C1] AS [C1], 
    (SELECT 
        SUM([Extent7].[PaidAmount]) AS [A1]
        FROM     [dbo].[TransactionLines] AS [Extent7]
        INNER JOIN [dbo].[Transactions] AS [Extent8] ON [Extent7].[TransactionId] = [Extent8].[Id]
        LEFT OUTER JOIN [dbo].[Eobs] AS [Extent9] ON [Extent8].[EobId] = [Extent9].[Id]
        LEFT OUTER JOIN [dbo].[EobBatches] AS [Extent10] ON [Extent9].[EobBatchId] = [Extent10].[Id]
        LEFT OUTER JOIN [dbo].[VisitLines] AS [Extent11] ON [Extent7].[VisitLineId] = [Extent11].[Id]
        WHERE (([Extent9].[EobBatchId] IS NULL) OR (1 = [Extent10].[Status])) AND ([Extent8].[TransactionTypeId] = 1433) AND (([Project5].[ProcedureId] = [Extent11].[ProcedureId]) OR (([Project5].[ProcedureId] IS NULL) AND ([Extent11].[ProcedureId] IS NULL)))) AS [C2]
    FROM ( SELECT 
        [Project4].[ProcedureId] AS [ProcedureId], 
        [Project4].[C1] AS [C1]
        FROM ( SELECT 
            [Project2].[ProcedureId] AS [ProcedureId], 
            (SELECT TOP (1) 
                [Extent6].[Code] AS [Code]
                FROM [dbo].[Procedures] AS [Extent6]
                WHERE [Extent6].[Id] = [Project2].[ProcedureId]) AS [C1]
            FROM ( SELECT 
                [Distinct1].[ProcedureId] AS [ProcedureId]
                FROM ( SELECT DISTINCT 
                    [Extent5].[ProcedureId] AS [ProcedureId]
                    FROM     [dbo].[TransactionLines] AS [Extent1]
                    INNER JOIN [dbo].[Transactions] AS [Extent2] ON [Extent1].[TransactionId] = [Extent2].[Id]
                    LEFT OUTER JOIN [dbo].[Eobs] AS [Extent3] ON [Extent2].[EobId] = [Extent3].[Id]
                    LEFT OUTER JOIN [dbo].[EobBatches] AS [Extent4] ON [Extent3].[EobBatchId] = [Extent4].[Id]
                    LEFT OUTER JOIN [dbo].[VisitLines] AS [Extent5] ON [Extent1].[VisitLineId] = [Extent5].[Id]
                    WHERE (([Extent3].[EobBatchId] IS NULL) OR (1 = [Extent4].[Status])) AND ([Extent2].[TransactionTypeId] = 1433)
                )  AS [Distinct1]
            )  AS [Project2]
        )  AS [Project4]
    )  AS [Project5]
)  AS [Project6]

查询时间为~3秒。如果直接使用Group By写sql查询，则查询时间为1.5秒，节省一半的CPU资源。

    SELECT sq.ProcedureId, SUM(sq.PaidAmount), (SELECT TOP(1) Procedures.Code From Procedures Where Procedures.Id = sq.ProcedureId) as Code
FROM(
    SELECT [Extent5].[ProcedureId] AS [ProcedureId],[Extent1].PaidAmount as [PaidAmount]
    FROM     [dbo].[TransactionLines] AS [Extent1]
    INNER JOIN [dbo].[Transactions] AS [Extent2] ON [Extent1].[TransactionId] = [Extent2].[Id]
    LEFT OUTER JOIN [dbo].[Eobs] AS [Extent3] ON [Extent2].[EobId] = [Extent3].[Id]
    LEFT OUTER JOIN [dbo].[EobBatches] AS [Extent4] ON [Extent3].[EobBatchId] = [Extent4].[Id]
    LEFT OUTER JOIN [dbo].[VisitLines] AS [Extent5] ON [Extent1].[VisitLineId] = [Extent5].[Id]
    WHERE (([Extent3].[EobBatchId] IS NULL) OR (1 = [Extent4].[Status])) AND ([Extent2].[TransactionTypeId] = 1433)
) sq
GROUP BY sq.ProcedureId

我写了不同的链接，但仍然不能强制EF生成GroupBy而不是子查询。理想情况下，我不想使用函数或手动编写sql，因为我在构建linq逻辑时有很多条件。

是否有可能强制EF生成与linq中编写的完全相同的SQL ?

实体框架GroupBy到Sql生成

尽量避免

context.Procedures.Where(h => h.Id == x.Key).Select(h => h.Code).FirstOrDefault()

通过在GroupBy子句中包含Code—我知道这似乎是多余的，但是EF在翻译涉及到除使用键访问器和聚合之外的其他内容的分组操作时存在问题:

//...
.GroupBy(x => new { Id = x.VisitLine.ProcedureId, x.VisitLine.Procedure.Code })
.Select(x => new
{
    Id = x.Key.Id,
    PaidAmount = x.Sum(t => t.PaidAmount),
    Code = x.Key.Code
}).ToArray();

Update:在我的测试环境(最新的EF6.1.3)中生成以下SQL:

SELECT
    1 AS [C1],
    [GroupBy1].[K1] AS [ProcedureId],
    [GroupBy1].[A1] AS [C2],
    [GroupBy1].[K2] AS [Code]
    FROM ( SELECT
        [Extent5].[ProcedureId] AS [K1],
        [Extent6].[Code] AS [K2],
        SUM([Filter1].[PaidAmount]) AS [A1]
        FROM    (SELECT [Extent1].[VisitLineId] AS [VisitLineId], [Extent1].[PaidAmount] AS [PaidAmount]
            FROM    [dbo].[TransactionLine] AS [Extent1]
            INNER JOIN [dbo].[Transaction] AS [Extent2] ON [Extent1].[TransactionId] = [Extent2].[Id]
            LEFT OUTER JOIN [dbo].[Eob] AS [Extent3] ON [Extent2].[EobId] = [Extent3].[Id]
            LEFT OUTER JOIN [dbo].[EobBatch] AS [Extent4] ON [Extent3].[EobBatchId] = [Extent4].[Id]
            WHERE (1433 = [Extent2].[TransactionTypeId]) AND ([Extent3].[EobBatchId] IS NULL OR [Extent4].[Status] = 1) ) AS [Filter1]
        LEFT OUTER JOIN [dbo].[VisitLine] AS [Extent5] ON [Filter1].[VisitLineId] = [Extent5].[Id]
        LEFT OUTER JOIN [dbo].[Procedure] AS [Extent6] ON [Extent5].[ProcedureId] = [Extent6].[Id]
        GROUP BY [Extent5].[ProcedureId], [Extent6].[Code]
    )  AS [GroupBy1]

这比我预期的要好得多。

更新2: EF是一个奇怪的野兽。使用双投影会产生期望的结果:

//...
.GroupBy(x => x.VisitLine.ProcedureId)
.Select(x => new
{
    Id = x.Key,
    PaidAmount = x.Sum(t => t.PaidAmount),
})
.Select(x => new
{
    x.Id,
    x.PaidAmount,
    Code = context.Procedures.Where(h => h.Id == x.Id).Select(h => h.Code).FirstOrDefault()
}).ToArray();

生成以下内容:

SELECT
    1 AS [C1],
    [Project2].[ProcedureId] AS [ProcedureId],
    [Project2].[C1] AS [C2],
    [Project2].[C2] AS [C3]
    FROM ( SELECT
        [GroupBy1].[A1] AS [C1],
        [GroupBy1].[K1] AS [ProcedureId],
        (SELECT TOP (1)
            [Extent6].[Code] AS [Code]
            FROM [dbo].[Procedure] AS [Extent6]
            WHERE [Extent6].[Id] = [GroupBy1].[K1]) AS [C2]
        FROM ( SELECT
            [Extent5].[ProcedureId] AS [K1],
            SUM([Filter1].[PaidAmount]) AS [A1]
            FROM   (SELECT [Extent1].[VisitLineId] AS [VisitLineId], [Extent1].[PaidAmount] AS [PaidAmount]
                FROM    [dbo].[TransactionLine] AS [Extent1]
                INNER JOIN [dbo].[Transaction] AS [Extent2] ON [Extent1].[TransactionId] = [Extent2].[Id]
                LEFT OUTER JOIN [dbo].[Eob] AS [Extent3] ON [Extent2].[EobId] = [Extent3].[Id]
                LEFT OUTER JOIN [dbo].[EobBatch] AS [Extent4] ON [Extent3].[EobBatchId] = [Extent4].[Id]
                WHERE (1433 = [Extent2].[TransactionTypeId]) AND ([Extent3].[EobBatchId] IS NULL OR [Extent4].[Status] = 1) ) AS [Filter1]
            LEFT OUTER JOIN [dbo].[VisitLine] AS [Extent5] ON [Filter1].[VisitLineId] = [Extent5].[Id]
            GROUP BY [Extent5].[ProcedureId]
        )  AS [GroupBy1]
    )  AS [Project2]

注:如果不清楚，你的具体问题的答案

是否有可能强制EF生成与linq中完全相同的SQL ?

是否定的。相反，您应该以某种方式编写LINQ查询，以便获得所需的(或更接近的)SQL查询。

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