我坚持使用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]
查询持续时间约为3秒.
如果直接使用Group By编写sql查询,则查询持续时间为1.5秒,并且它使用的资源减少了一半.
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linqs但仍然无法强制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SQL完全相同的SQL？
最佳答案 试着避免
context.Procedures.Where(h => h.Id == x.Key).Select(h => h.Code).FirstOrDefault()
通过在GroupBy子句中包含Code – 我知道它似乎是多余的,但是已知EF在转换分组操作时遇到问题,这些操作涉及除了使用密钥访问器和聚合之外的其他内容：
//...
.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();
更新：以上在我的测试环境中生成以下SQL(最新的EF6.1.3)：
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]
这比我预想的要好得多.
更新2：EF是一个奇怪的野兽.使用双投影可产生所需的结果：
//...
.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();
产生以下内容：
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]
附：如果不清楚,请回答您的具体问题
Is it possible to force EF to generate SQL exactly as it was written within linq ?
没有.相反,您应该以某种方式编写LINQ查询,以获得所需(或更接近)的SQL查询.
