Question

我对我们的Microsoft sql数据库的查询很慢。而且，如果我删除了一部分，它的速度会加快，但是我不明白为什么，查询计划程序也无法帮助我（有一些我所缺少的东西）。

查询时间超过30秒（queryplan）：

SELECT COUNT(*)
FROM [dbo].[CarImage] AS [t0]
     LEFT OUTER JOIN [dbo].[Dismantled] AS [t1] ON [t1].[Id] = [t0].[DismantledId]
WHERE([t1].[FinishedReason] <> 0)
     AND ([t1].[FinishedDate] < GETDATE() - 365)
     AND (NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Part] AS [t2]
    WHERE([t2].[Status] <> 4)
         AND ([t2].[Status] <> 3)
         AND ([t2].[DismantledId] = [t1].[Id])
)))
     AND (NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Part] AS [t3]
    WHERE([t3].[Status] = 3)
         AND ([t3].[SoldDate] > GETDATE() - 365)
         AND ([t3].[DismantledId] = [t1].[Id])
)))
     AND ((NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Partner] AS [t4], 
         [dbo].[SelfPickSite] AS [t5]
    WHERE([t4].[Id] = [t1].[PartnerId])
         AND ([t5].[PartnerId] = [t4].[Id])
)))
          OR (EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[SelfPickCar] AS [t6]
    WHERE [t6].[DismantledId] = [t1].[Id]
)));

如果我删除最后一部分，则是<1秒（queryplan）：

SELECT COUNT(*)
FROM [dbo].[CarImage] AS [t0]
     LEFT OUTER JOIN [dbo].[Dismantled] AS [t1] ON [t1].[Id] = [t0].[DismantledId]
WHERE([t1].[FinishedReason] <> 0)
     AND ([t1].[FinishedDate] < GETDATE() - 365)
     AND (NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Part] AS [t2]
    WHERE([t2].[Status] <> 4)
         AND ([t2].[Status] <> 3)
         AND ([t2].[DismantledId] = [t1].[Id])
)))
     AND (NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Part] AS [t3]
    WHERE([t3].[Status] = 3)
         AND ([t3].[SoldDate] > GETDATE() - 365)
         AND ([t3].[DismantledId] = [t1].[Id])
)))
     AND ((NOT(EXISTS
(
    SELECT NULL AS [EMPTY]
    FROM [dbo].[Partner] AS [t4], 
         [dbo].[SelfPickSite] AS [t5]
    WHERE([t4].[Id] = [t1].[PartnerId])
         AND ([t5].[PartnerId] = [t4].[Id])
))));

Answer 1

OR是性能杀手；请尝试此查询并给我结果

Any

ps：如果您遇到性能问题，请运行以下代码SELECT COUNT(*) FROM ( SELECT 1 FROM [dbo].[CarImage] AS [t0] LEFT JOIN [dbo].[Dismantled] AS [t1] ON [t1].[Id] = [t0].[DismantledId] WHERE ([t1].[FinishedReason] <> 0) AND ([t1].[FinishedDate] < GETDATE() - 365) AND ( NOT ( EXISTS ( SELECT NULL AS [EMPTY] FROM [dbo].[Part] AS [t2] WHERE ([t2].[Status] <> 4) AND ([t2].[Status] <> 3) AND ([t2].[DismantledId] = [t1].[Id]) ) ) ) AND ( NOT ( EXISTS ( SELECT NULL AS [EMPTY] FROM [dbo].[Part] AS [t3] WHERE ([t3].[Status] = 3) AND ([t3].[SoldDate] > GETDATE() - 365) AND ([t3].[DismantledId] = [t1].[Id]) ) ) ) AND ( ( NOT ( EXISTS ( SELECT NULL AS [EMPTY] FROM [dbo].[Partner] AS [t4] ,[dbo].[SelfPickSite] AS [t5] WHERE ([t4].[Id] = [t1].[PartnerId]) AND ([t5].[PartnerId] = [t4].[Id]) ) ) ) UNION ALL SELECT 1 FROM [dbo].[CarImage] AS [t0] LEFT JOIN [dbo].[Dismantled] AS [t1] ON [t1].[Id] = [t0].[DismantledId] WHERE ( EXISTS ( SELECT NULL AS [EMPTY] FROM [dbo].[SelfPickCar] AS [t6] WHERE [t6].[DismantledId] = [t1].[Id] ) ) ) ) X，然后运行查询并发布结果

我不明白为什么这个查询很慢

1 个答案: