EF 6 查找生成派生自语句

Question

我对 EF 6 的 Find 方法生成派生查询的原因感到困惑。我在LinqPad中运行下面两条语句：

using (var ctx = new ApplicationDbContext())
            {
                var z = ctx.TicketTracker.Find(11277);
                var x = ctx.TicketTracker.Where(w => w.TicketTrackerId == 11277).FirstOrDefault();
                
            }

这是输出：

SELECT 
[Limit1].[TicketTrackerId] AS [TicketTrackerId], 
[Limit1].[BusinessId] AS [BusinessId], 
[Limit1].[DeviceId] AS [DeviceId], 
[Limit1].[ETicketStorageId] AS [ETicketStorageId], 
[Limit1].[TicketJSON] AS [TicketJSON], 
[Limit1].[DriverUpdateId] AS [DriverUpdateId], 
[Limit1].[OrderNumber] AS [OrderNumber], 
[Limit1].[OrderKey] AS [OrderKey], 
[Limit1].[TicketNumber] AS [TicketNumber], 
[Limit1].[CustomerId] AS [CustomerId], 
[Limit1].[VehicleId] AS [VehicleId], 
[Limit1].[Plant] AS [Plant], 
[Limit1].[Notes] AS [Notes], 
[Limit1].[PostedToKeystone] AS [PostedToKeystone], 
[Limit1].[EmailSuccess] AS [EmailSuccess], 
[Limit1].[EmailRecipients] AS [EmailRecipients], 
[Limit1].[FormType] AS [FormType], 
[Limit1].[Usage] AS [Usage], 
[Limit1].[JobId] AS [JobId], 
[Limit1].[JobLot] AS [JobLot], 
[Limit1].[CustomerPo] AS [CustomerPo], 
[Limit1].[CreateDate] AS [CreateDate], 
[Limit1].[PostedToKeystoneDate] AS [PostedToKeystoneDate], 
[Limit1].[Devices_DeviceId] AS [Devices_DeviceId]
FROM ( SELECT TOP (2) 
    [Extent1].[TicketTrackerId] AS [TicketTrackerId], 
    [Extent1].[BusinessId] AS [BusinessId], 
    [Extent1].[DeviceId] AS [DeviceId], 
    [Extent1].[ETicketStorageId] AS [ETicketStorageId], 
    [Extent1].[TicketJSON] AS [TicketJSON], 
    [Extent1].[DriverUpdateId] AS [DriverUpdateId], 
    [Extent1].[OrderNumber] AS [OrderNumber], 
    [Extent1].[OrderKey] AS [OrderKey], 
    [Extent1].[TicketNumber] AS [TicketNumber], 
    [Extent1].[CustomerId] AS [CustomerId], 
    [Extent1].[VehicleId] AS [VehicleId], 
    [Extent1].[Plant] AS [Plant], 
    [Extent1].[Notes] AS [Notes], 
    [Extent1].[PostedToKeystone] AS [PostedToKeystone], 
    [Extent1].[EmailSuccess] AS [EmailSuccess], 
    [Extent1].[EmailRecipients] AS [EmailRecipients], 
    [Extent1].[FormType] AS [FormType], 
    [Extent1].[Usage] AS [Usage], 
    [Extent1].[JobId] AS [JobId], 
    [Extent1].[JobLot] AS [JobLot], 
    [Extent1].[CustomerPo] AS [CustomerPo], 
    [Extent1].[CreateDate] AS [CreateDate], 
    [Extent1].[PostedToKeystoneDate] AS [PostedToKeystoneDate], 
    [Extent1].[Devices_DeviceId] AS [Devices_DeviceId]
    FROM [ETicket].[TicketTracker] AS [Extent1]
    WHERE [Extent1].[TicketTrackerId] = @p0
)  AS [Limit1]
GO

SELECT TOP (1) 
    [Extent1].[TicketTrackerId] AS [TicketTrackerId], 
    [Extent1].[BusinessId] AS [BusinessId], 
    [Extent1].[DeviceId] AS [DeviceId], 
    [Extent1].[ETicketStorageId] AS [ETicketStorageId], 
    [Extent1].[TicketJSON] AS [TicketJSON], 
    [Extent1].[DriverUpdateId] AS [DriverUpdateId], 
    [Extent1].[OrderNumber] AS [OrderNumber], 
    [Extent1].[OrderKey] AS [OrderKey], 
    [Extent1].[TicketNumber] AS [TicketNumber], 
    [Extent1].[CustomerId] AS [CustomerId], 
    [Extent1].[VehicleId] AS [VehicleId], 
    [Extent1].[Plant] AS [Plant], 
    [Extent1].[Notes] AS [Notes], 
    [Extent1].[PostedToKeystone] AS [PostedToKeystone], 
    [Extent1].[EmailSuccess] AS [EmailSuccess], 
    [Extent1].[EmailRecipients] AS [EmailRecipients], 
    [Extent1].[FormType] AS [FormType], 
    [Extent1].[Usage] AS [Usage], 
    [Extent1].[JobId] AS [JobId], 
    [Extent1].[JobLot] AS [JobLot], 
    [Extent1].[CustomerPo] AS [CustomerPo], 
    [Extent1].[CreateDate] AS [CreateDate], 
    [Extent1].[PostedToKeystoneDate] AS [PostedToKeystoneDate], 
    [Extent1].[Devices_DeviceId] AS [Devices_DeviceId]
    FROM [ETicket].[TicketTracker] AS [Extent1]
    WHERE 11277 = [Extent1].[TicketTrackerId]

我希望 Find 能够简单地生成一个 select 语句，但在我开始切换代码之前，EF 使用简单方法添加这个复杂查询是否有原因？我读过 Find 使用内部缓存而 Where 没有，但除此之外我还缺少什么？

Answer 1

这些查询是正常的，不会导致任何性能问题。对于一些更复杂的查询，您可能会发现编写自定义的 Raw SQL Query 是值得的，但在本例中不是。

this query is always either taking up too many resources or is the slowest.

打开 Query Store 以了解它正在占用哪些资源以及速度缓慢的原因。

Answer 2

当您看到随机查询运行似乎无缘无故地变慢，或者资源消耗非常高时，这通常是索引问题的迹象。

-- 将此答案放在这里，因为这实际上是 OP 查询的问题。

EF 6 查找生成派生自语句

EF 6 Find Generates Derived From Statement

c#

linq

entity-framework-6