Question

我的Linq查询在我的开发服务器上“快速”运行，在生产服务器上运行速度非常慢（本地2秒，生产3分钟）。在尝试调查和比较两者的执行计划时，我决定从sp_executesql语句中“解包”Linq查询，并在本地（快速）环境中将其作为动态查询运行。

现在同一个服务器，相同的查询但是一个包裹在sp_executesql内的另一个动态在运行时间上有更大的差距：前者在2秒内运行，后者需要14分钟。

我正在读这篇文章 http://technet.microsoft.com/en-au/library/cc966425.aspx 在哪里解释sp_executesql如何使用缓存的执行计划，是否会构成13分钟和58秒的差异？

我认为发布实际查询可能无关紧要（并且看起来很丑陋和复杂）但是，如果可以提供更多洞察力，我会将它们粘贴到此处。

首先，在2秒内执行：

exec sp_executesql N'SELECT [t0].[id] AS [Id], (CONVERT(Float,[dbo].[RankWords]((
    SELECT [t18].[searchable_1]
    FROM (
        SELECT TOP (1) [t17].[searchable_1]
        FROM [dbo].[contents] AS [t17]
        WHERE [t17].[navigation_tree_id] = [t0].[id]
        ) AS [t18]
    ), @p12, @p13, @p14))) + (CONVERT(Float,[dbo].[RankWords]((
    SELECT [t20].[name]
    FROM (
        SELECT TOP (1) [t19].[name]
        FROM [dbo].[contents] AS [t19]
        WHERE [t19].[navigation_tree_id] = [t0].[id]
        ) AS [t20]
    ), @p15, @p16, @p17))) AS [GlobalRank], [t0].[modified_date] AS [ModifiedDate], [t0].[parent_id] AS [ParentId], [t0].[template_id] AS [TemplateId], (
    SELECT [t22].[name]
    FROM (
        SELECT TOP (1) [t21].[name]
        FROM [dbo].[contents] AS [t21]
        WHERE [t21].[navigation_tree_id] = [t0].[id]
        ) AS [t22]
    ) AS [Name], [t0].[id] AS [id2], [t0].[uri], [t0].[site_id], [t0].[list_order], [t0].[pointed_node_id], [t0].[start_date], [t0].[expiry_date], [t0].[is_external_link], [t0].[priority_level], [t0].[is_active], [t0].[power_level_required]
FROM [dbo].[navigation_trees] AS [t0]
WHERE (((
    SELECT COUNT(*)
    FROM [dbo].[label__navigation_tree] AS [t1]
    WHERE [t1].[navigation_tree_id] = [t0].[id]
    )) > @p0) AND ([t0].[template_id] IS NOT NULL) AND (([t0].[template_id]) IN (@p1, @p2, @p3)) AND (EXISTS(
    SELECT TOP (1) NULL AS [EMPTY]
    FROM [dbo].[contents] AS [t2]
    WHERE [t2].[navigation_tree_id] = [t0].[id]
    )) AND (((CONVERT(Bit,[dbo].[HasMatch](
    (CASE 
        WHEN ((
            SELECT [t4].[name]
            FROM (
                SELECT TOP (1) [t3].[name]
                FROM [dbo].[contents] AS [t3]
                WHERE [t3].[navigation_tree_id] = [t0].[id]
                ) AS [t4]
            )) IS NOT NULL THEN CONVERT(NVarChar(MAX),(
            SELECT [t6].[name]
            FROM (
                SELECT TOP (1) [t5].[name]
                FROM [dbo].[contents] AS [t5]
                WHERE [t5].[navigation_tree_id] = [t0].[id]
                ) AS [t6]
            ))
        WHEN (@p4 + ((
            SELECT [t8].[title]
            FROM (
                SELECT TOP (1) [t7].[title]
                FROM [dbo].[contents] AS [t7]
                WHERE [t7].[navigation_tree_id] = [t0].[id]
                ) AS [t8]
            ))) IS NOT NULL THEN CONVERT(NVarChar(MAX),@p5 + ((
            SELECT [t10].[title]
            FROM (
                SELECT TOP (1) [t9].[title]
                FROM [dbo].[contents] AS [t9]
                WHERE [t9].[navigation_tree_id] = [t0].[id]
                ) AS [t10]
            )))
        WHEN (@p6 + ((
            SELECT [t12].[description]
            FROM (
                SELECT TOP (1) [t11].[description]
                FROM [dbo].[contents] AS [t11]
                WHERE [t11].[navigation_tree_id] = [t0].[id]
                ) AS [t12]
            ))) IS NOT NULL THEN @p7 + ((
            SELECT [t14].[description]
            FROM (
                SELECT TOP (1) [t13].[description]
                FROM [dbo].[contents] AS [t13]
                WHERE [t13].[navigation_tree_id] = [t0].[id]
                ) AS [t14]
            ))
        ELSE CONVERT(NVarChar(MAX),@p8)
     END), @p9))) = 1) OR ((CONVERT(Bit,[dbo].[HasMatch]((
    SELECT [t16].[searchable_1]
    FROM (
        SELECT TOP (1) [t15].[searchable_1]
        FROM [dbo].[contents] AS [t15]
        WHERE [t15].[navigation_tree_id] = [t0].[id]
        ) AS [t16]
    ), @p10))) = 1)) AND ([t0].[pointed_node_id] IS NULL) AND ([t0].[site_id] = @p11) AND ([t0].[is_active] = 1)',N'@p0 int,@p1 int,@p2 int,@p3 int,@p4 nvarchar(4000),@p5 nvarchar(1),@p6 nvarchar(4000),@p7 nvarchar(1),@p8 nvarchar(4000),@p9 nvarchar(3),@p10 nvarchar(3),@p11 int,@p12 nvarchar(3),@p13 int,@p14 bit,@p15 nvarchar(3),@p16 int,@p17 bit',@p0=0,@p1=158,@p2=159,@p3=160,@p4=N'',@p5=N' ',@p6=N'',@p7=N' ',@p8=N'',@p9=N'actor',@p10=N'actor',@p11=15,@p12=N'actor',@p13=3,@p14=0,@p15=N'actor',@p16=3,@p17=0

第二个在14分钟内执行：

DECLARE @p0 int,@p1 int,@p2 int,@p3 int,@p4 nvarchar(4000),@p5 nvarchar(1),@p6 nvarchar(4000),@p7 nvarchar(1),@p8 nvarchar(4000),@p9 nvarchar(3),@p10 nvarchar(3),@p11 int,@p12 nvarchar(3),@p13 int,@p14 bit,@p15 nvarchar(3),@p16 int,@p17 bit

SET @p0=0
SET @p1=158
SET @p2=159
SET @p3=160
SET @p4=N''
SET @p5=N' '
SET @p6=N''
SET @p7=N' '
SET @p8=N''
SET @p9=N'actor'
SET @p10=N'actor'
SET @p11=15
SET @p12=N'actor'
SET @p13=3
SET @p14=0
SET @p15=N'actor'
SET @p16=3
SET @p17=0

SELECT 
    [t0].[id] AS [Id], 
    (
        CONVERT(Float,[dbo].[RankWords]
        ((
            SELECT [t18].[searchable_1]
            FROM (
                SELECT TOP (1) [t17].[searchable_1]
                FROM [dbo].[contents] AS [t17]
                WHERE [t17].[navigation_tree_id] = [t0].[id]
                ) AS [t18]
            ), 
            @p12, 
            @p13, 
            @p14
        ))
    ) + 
    (
        CONVERT(Float,[dbo].[RankWords]((
            SELECT [t20].[name]
            FROM (
                SELECT TOP (1) [t19].[name]
                FROM [dbo].[contents] AS [t19]
                WHERE [t19].[navigation_tree_id] = [t0].[id]
                ) AS [t20]
            ), 
            @p15, 
            @p16, 
            @p17
        ))
    ) 
    AS [GlobalRank], 
    [t0].[modified_date] AS [ModifiedDate], 
    [t0].[parent_id] AS [ParentId], 
    [t0].[template_id] AS [TemplateId], 
    (
        SELECT [t22].[name]
        FROM (
            SELECT TOP (1) [t21].[name]
            FROM [dbo].[contents] AS [t21]
            WHERE [t21].[navigation_tree_id] = [t0].[id]
            ) AS [t22]
    ) AS [Name], 
    [t0].[id] AS [id2], 
    [t0].[uri], 
    [t0].[site_id], 
    [t0].[list_order], 
    [t0].[pointed_node_id], 
    [t0].[start_date], 
    [t0].[expiry_date], 
    [t0].[is_external_link], 
    [t0].[priority_level], 
    [t0].[is_active], 
    [t0].[power_level_required]

FROM [dbo].[navigation_trees] AS [t0]
WHERE 

    (
        ((
        SELECT COUNT(*)
        FROM [dbo].[label__navigation_tree] AS [t1]
        WHERE [t1].[navigation_tree_id] = [t0].[id]
        )) > @p0
    ) 
    AND 
    ([t0].[template_id] IS NOT NULL) 
    AND 
    (([t0].[template_id]) IN (@p1, @p2, @p3)) 
    AND 
    (EXISTS(
        SELECT TOP (1) NULL AS [EMPTY]
        FROM [dbo].[contents] AS [t2]
        WHERE [t2].[navigation_tree_id] = [t0].[id]
    )) 
    AND 
    (
        ((
            CONVERT(Bit,[dbo].[HasMatch](
        (CASE 
            WHEN ((
                SELECT [t4].[name]
                FROM (
                    SELECT TOP (1) [t3].[name]
                    FROM [dbo].[contents] AS [t3]
                    WHERE [t3].[navigation_tree_id] = [t0].[id]
                    ) AS [t4]
                )) IS NOT NULL 
            THEN 
                CONVERT(NVarChar(MAX),
                (
                    SELECT [t6].[name]
                    FROM (
                        SELECT TOP (1) [t5].[name]
                        FROM [dbo].[contents] AS [t5]
                        WHERE [t5].[navigation_tree_id] = [t0].[id]
                        ) AS [t6]
                    )               
                )
            WHEN 
                (@p4 + ((SELECT [t8].[title]
                            FROM (
                                SELECT TOP (1) [t7].[title]
                                FROM [dbo].[contents] AS [t7]
                                WHERE [t7].[navigation_tree_id] = [t0].[id]
                                ) AS [t8]
                            ))
                ) IS NOT NULL 
            THEN CONVERT(NVarChar(MAX),@p5 + ((
                SELECT [t10].[title]
                FROM (
                    SELECT TOP (1) [t9].[title]
                    FROM [dbo].[contents] AS [t9]
                    WHERE [t9].[navigation_tree_id] = [t0].[id]
                    ) AS [t10]
                )))
            WHEN (@p6 + ((
                SELECT [t12].[description]
                FROM (
                    SELECT TOP (1) [t11].[description]
                    FROM [dbo].[contents] AS [t11]
                    WHERE [t11].[navigation_tree_id] = [t0].[id]
                    ) AS [t12]
                ))) IS NOT NULL THEN @p7 + ((
                SELECT [t14].[description]
                FROM (
                    SELECT TOP (1) [t13].[description]
                    FROM [dbo].[contents] AS [t13]
                    WHERE [t13].[navigation_tree_id] = [t0].[id]
                    ) AS [t14]
                ))
            ELSE CONVERT(NVarChar(MAX),@p8)
         END), @p9))) = 1)

        OR ((CONVERT(Bit,[dbo].[HasMatch]((
        SELECT [t16].[searchable_1]
        FROM (
            SELECT TOP (1) [t15].[searchable_1]
            FROM [dbo].[contents] AS [t15]
            WHERE [t15].[navigation_tree_id] = [t0].[id]
            ) AS [t16]
        ), @p10))) = 1)

    ) AND ([t0].[pointed_node_id] IS NULL) AND ([t0].[site_id] = @p11) AND ([t0].[is_active] = 1)

感谢。

编辑（添加解决方案的说明）：

我已经重写了Linq表达式以生成内部选择较少的精简查询，结果将动态查询从14分钟降低到35秒仍然与使用sp_executesql运行的查询之间保持33秒的差异和动态的。

然后我使用执行计划索引建议来创建以下索引：

CREATE NONCLUSTERED INDEX [JH_contents_navigation_tree_id]
ON [dbo].[contents] ([navigation_tree_id])


CREATE NONCLUSTERED INDEX [JH_label_navigation_tree_navigation_tree_id]
ON [dbo].[label__navigation_tree] ([navigation_tree_id])

CREATE NONCLUSTERED INDEX [JH_navigation_trees_sid_pnid_isactv_tmplid]
ON [dbo].[navigation_trees] ([site_id],[pointed_node_id],[is_active],[template_id])

将两个查询标记为几百毫秒。

这也解决了我的开发服务器和生产服务器之间执行时间差异的另一个问题，但是，虽然我可以解释生产和开发服务器之间执行时间的差异，直到服务器安装特性，但我仍然没有理解为什么在同一台服务器上运行sp_executesql的查询仍然非常快，尽管基础表仍然缺少索引！？（即使我已经标记为已回答，也请添加评论，这将很有趣）

所有建议都帮助我缩小了问题范围，谢谢大家。不过我觉得Aaron Kempf的回答确定了实际问题。

Answer 1

听起来像是使用了不同的计划，或者数据库中的数据不一样。

获取新的查询计划尝试向动态（不是sp_executesql）添加空格并重新运行它

您也可以尝试更新统计信息。

如果您在加入的列上转换/转换数据类型，也会发生这种情况。

Answer 2

我认为你应该考虑索引正确的字段。谁更关心哪一个更快，除非你返回了大量的行，我在过去的十年中没有任何查询超过30秒。

使用sp_executesql运行时的相同SQL查询是快速的，如果在查询分析器中作为动态查询执行，速度非常慢，为什么？

2 个答案: