我正在使用Linq-To-Entities进行查询,返回的结果只有947行,但运行时间达到了18秒。我已经使用"ToTraceString"获取底层SQL,并在数据库中直接运行相同的查询,时间也一样长。
我已经使用调优顾问并创建了一些索引,但影响很小。
查看查询执行计划,发现有几个嵌套循环占用了95%以上的时间,但这些循环已经在索引上运行了?
是否有任何想法来强制优化EF查询??
编辑:提供附加信息
三张表的基本ER图如下:
我正在运行的LINQ查询旨在获取特定人员(使用P_ID)的所有事件:
我已经使用调优顾问并创建了一些索引,但影响很小。
查看查询执行计划,发现有几个嵌套循环占用了95%以上的时间,但这些循环已经在索引上运行了?
是否有任何想法来强制优化EF查询??
编辑:提供附加信息
三张表的基本ER图如下:
People >----People_Event_Link ----< Events
P_ID P_ID E_ID
E_ID
我正在运行的LINQ查询旨在获取特定人员(使用P_ID)的所有事件:
var query = from ev in genesisContext.Events
join pe in genesisContext.People_Event_Link
on ev equals pe.Event
where pe.P_ID == key
select ev;
return query;
以下是生成的SQL语句(深呼吸!):
SELECT
1 AS [C1],
[Extent1].[E_ID] AS [E_ID],
[Extent1].[E_START_DATE] AS [E_START_DATE],
[Extent1].[E_END_DATE] AS [E_END_DATE],
[Extent1].[E_COMMENTS] AS [E_COMMENTS],
[Extent1].[E_DATE_ADDED] AS [E_DATE_ADDED],
[Extent1].[E_RECORDED_BY] AS [E_RECORDED_BY],
[Extent1].[E_DATE_UPDATED] AS [E_DATE_UPDATED],
[Extent1].[E_UPDATED_BY] AS [E_UPDATED_BY],
[Extent1].[ET_ID] AS [ET_ID],
[Extent1].[L_ID] AS [L_ID]
FROM [dbo].[Events] AS [Extent1]
INNER JOIN [dbo].[People_Event_Link] AS [Extent2] ON EXISTS (SELECT
1 AS [C1]
FROM ( SELECT 1 AS X ) AS [SingleRowTable1]
LEFT OUTER JOIN (SELECT
[Extent3].[E_ID] AS [E_ID]
FROM [dbo].[Events] AS [Extent3]
WHERE [Extent2].[E_ID] = [Extent3].[E_ID] ) AS [Project1] ON 1 = 1
LEFT OUTER JOIN (SELECT
[Extent4].[E_ID] AS [E_ID]
FROM [dbo].[Events] AS [Extent4]
WHERE [Extent2].[E_ID] = [Extent4].[E_ID] ) AS [Project2] ON 1 = 1
WHERE ([Extent1].[E_ID] = [Project1].[E_ID]) OR (([Extent1].[E_ID] IS NULL) AND ([Project2].[E_ID] IS NULL))
)
WHERE [Extent2].[P_ID] = 291