我们正在努力解决一个奇怪的问题：当原始SQL执行得相当快时，存储过程会变得非常慢。
我们有
代码：
ALTER Procedure [dbo].[spGetMovieShortDataList](
@MediaID int = null,
@Rfa nvarchar(8) = null,
@LicenseWindow nvarchar(8) = null,
@OwnerID uniqueidentifier = null,
@LicenseType nvarchar(max) = null,
@PriceGroupID uniqueidentifier = null,
@Format nvarchar(max) = null,
@GenreID uniqueidentifier = null,
@Title nvarchar(max) = null,
@Actor nvarchar(max) = null,
@ProductionCountryID uniqueidentifier = null,
@DontReturnMoviesWithNoLicense bit = 0,
@DontReturnNotReadyMovies bit = 0,
@take int = 10,
@skip int = 0,
@order nvarchar(max) = null,
@asc bit = 1)
as
begin
declare @SQLString nvarchar(max);
declare @ascending nvarchar(5);
declare @ParmDefinition nvarchar(max);
set @ParmDefinition = '@MediaID int,
declare @now DateTime;
declare @Rfa nvarchar(8),
@LicenseWindow nvarchar(8),
@OwnerID uniqueidentifier,
@LicenseType nvarchar(max),
@PriceGroupID uniqueidentifier,
@Format nvarchar(max),
@GenreID uniqueidentifier,
@Title nvarchar(max),
@Actor nvarchar(max),
@ProductionCountryID uniqueidentifier,
@DontReturnMoviesWithNoLicense bit = 0,
@DontReturnNotReadyMovies bit = 0,
@take int,
@skip int,
@now DateTime';
set @ascending = case when @asc = 1 then 'ASC' else 'DESC' end
set @now = GetDate();
set @SQLString = 'SELECT distinct m.ID, m.EpisodNo, m.MediaID, p.Dubbed, pf.Format, t.OriginalTitle into #temp
FROM Media m
inner join Asset a1 on m.ID=a1.ID
inner join Asset a2 on a1.ParentID=a2.ID
inner join Asset a3 on a2.ParentID=a3.ID
inner join Title t on t.ID = a3.ID
inner join Product p on a2.ID = p.ID
left join AssetReady ar on ar.AssetID = a1.ID
left join License l on l.ProductID=p.ID
left join ProductFormat pf on pf.ID = p.Format '
+ CASE WHEN @PriceGroupID IS NOT NULL THEN
'left join LicenseToPriceGroup lpg on lpg.LicenseID = l.ID ' ELSE '' END
+ CASE WHEN @Title IS NOT NULL THEN
'left join LanguageAsset la on la.AssetID = m.ID ' ELSE '' END
+ CASE WHEN @LicenseType IS NOT NULL THEN
'left join LicenseType lt on lt.ID=l.LicenseTypeID ' ELSE '' END
+ CASE WHEN @Actor IS NOT NULL THEN
'left join Cast c on c.AssetID = a1.ID ' ELSE '' END
+ CASE WHEN @GenreID IS NOT NULL THEN
'left join ListToCountryToAsset lca on lca.AssetID=a1.ID ' ELSE '' END
+ CASE WHEN @ProductionCountryID IS NOT NULL THEN
'left join ProductionCountryToAsset pca on pca.AssetID=t.ID ' ELSE '' END
+
'where (
1 = case
when @Rfa = ''All'' then 1
when @Rfa = ''Ready'' then ar.Rfa
when @Rfa = ''NotReady'' and (l.TbaWindowStart is null OR l.TbaWindowStart = 0) and ar.Rfa = 0 and ar.SkipRfa = 0 then 1
when @Rfa = ''Skipped'' and ar.SkipRfa = 1 then 1
end) '
+
CASE WHEN @LicenseWindow IS NOT NULL THEN
'AND
1 = (case
when (@LicenseWindow = 1 And (l.WindowEnd < @now and l.TbaWindowEnd = 0)) then 1
when (@LicenseWindow = 2 And (l.TbaWindowStart = 0 and l.WindowStart < @now and (l.TbaWindowEnd = 1 or l.WindowEnd > @now))) then 1
when (@LicenseWindow = 4 And ((l.TbaWindowStart = 1 or l.WindowStart > @now) and (l.TbaWindowEnd = 1 or l.WindowEnd > @now))) then 1
when (@LicenseWindow = 3 And ((l.WindowEnd < @now and l.TbaWindowEnd = 0) or (l.TbaWindowStart = 0 and l.WindowStart < @now and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)))) then 1
when (@LicenseWindow = 5 And ((l.WindowEnd < @now and l.TbaWindowEnd = 0) or ((l.TbaWindowStart = 1 or l.WindowStart > @now) and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)))) then 1
when (@LicenseWindow = 6 And ((l.TbaWindowStart = 0 and l.WindowStart < @now and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)) or ((l.TbaWindowStart = 1 or l.WindowStart > @now) and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)))) then 1
when ((@LicenseWindow = 7 Or @LicenseWindow = 0) And ((l.WindowEnd < @now and l.TbaWindowEnd = 0) or (l.TbaWindowStart = 0 and l.WindowStart < @now and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)) or ((l.TbaWindowStart = 1 or l.WindowStart > @now) and (l.TbaWindowEnd = 1 or l.WindowEnd > @now)))) then 1
end) ' ELSE '' END
+ CASE WHEN @OwnerID IS NOT NULL THEN
'AND (l.OwnerID = @OwnerID) ' ELSE '' END
+ CASE WHEN @MediaID IS NOT NULL THEN
'AND (m.MediaID = @MediaID) ' ELSE '' END
+ CASE WHEN @LicenseType IS NOT NULL THEN
'AND (lt.Name = @LicenseType) ' ELSE '' END
+ CASE WHEN @PriceGroupID IS NOT NULL THEN
'AND (lpg.PriceGroupID = @PriceGroupID) ' ELSE '' END
+ CASE WHEN @Format IS NOT NULL THEN
'AND (pf.Format = @Format) ' ELSE '' END
+ CASE WHEN @GenreID IS NOT NULL THEN
'AND (lca.ListID = @GenreID) ' ELSE '' END
+ CASE WHEN @DontReturnMoviesWithNoLicense = 1 THEN
'AND (l.ID is not null) ' ELSE '' END
+ CASE WHEN @Title IS NOT NULL THEN
'AND (t.OriginalTitle like N''%' + @Title + '%'' OR la.LocalTitle like N''%' + @Title + '%'') ' ELSE '' END
+ CASE WHEN @Actor IS NOT NULL THEN
'AND (rtrim(ltrim(replace(c.FirstName + '' '' + c.MiddleName + '' '' + c.LastName, '' '', '' ''))) like ''%'' + rtrim(ltrim(replace(@Actor,'' '','' ''))) + ''%'') ' ELSE '' END
+ CASE WHEN @DontReturnNotReadyMovies = 1 THEN
'AND ((ar.ID is not null) AND (ar.Ready = 1) AND (ar.CountryID = l.CountryID))' ELSE '' END
+ CASE WHEN @ProductionCountryID IS NOT NULL THEN
'AND (pca.ProductionCountryID = @ProductionCountryID)' ELSE '' END
+
'
select #temp.* ,ROW_NUMBER() over (order by ';
if @order = 'Title'
begin
set @SQLString = @SQLString + 'OriginalTitle';
end
else if @order = 'MediaID'
begin
set @SQLString = @SQLString + 'MediaID';
end
else
begin
set @SQLString = @SQLString + 'ID';
end
set @SQLString = @SQLString + ' ' + @ascending + '
) rn
into #numbered
from #temp
declare @count int;
select @count = MAX(#numbered.rn) from #numbered
while (@skip >= @count )
begin
set @skip = @skip - @take;
end
select ID, MediaID, EpisodNo, Dubbed, Format, OriginalTitle, @count TotalCount from #numbered
where rn between @skip and @skip + @take
drop table #temp
drop table #numbered';
execute sp_executesql @SQLString,@ParmDefinition, @MediaID, @Rfa, @LicenseWindow, @OwnerID, @LicenseType, @PriceGroupID, @Format, @GenreID,
@Title, @Actor, @ProductionCountryID, @DontReturnMoviesWithNoLicense,@DontReturnNotReadyMovies, @take, @skip, @now
end
存储过程工作得很好而且速度很快（执行通常需要1-2秒）。
电话示例
DBCC FREEPROCCACHE
EXEC value = [dbo].[spGetMovieShortDataList]
@LicenseWindow =N'1',
@Rfa = N'NotReady',
@DontReturnMoviesWithNoLicense = False,
@DontReturnNotReadyMovies = True,
@take = 20,
@skip = 0,
@asc = False,
@order = N'ID'
在执行存储过程执行3个SQL查询时，第一个Select Into查询占用了99％的时间。
此查询
declare @now DateTime;
set @now = GetDate();
SELECT DISTINCT
m.ID, m.EpisodNo, m.MediaID, p.Dubbed, pf.Format, t.OriginalTitle
FROM Media m
INNER JOIN Asset a1 ON m.ID = a1.ID
INNER JOIN Asset a2 ON a1.ParentID = a2.ID
INNER JOIN Asset a3 ON a2.ParentID = a3.ID
INNER JOIN Title t ON t.ID = a3.ID
INNER JOIN Product p ON a2.ID = p.ID
LEFT JOIN AssetReady ar ON ar.AssetID = a1.ID
LEFT JOIN License l on l.ProductID = p.ID
LEFT JOIN ProductFormat pf on pf.ID = p.Format
WHERE
((l.TbaWindowStart is null OR l.TbaWindowStart = 0)
and ar.Rfa = 0 and ar.SkipRfa = 0)
And (l.WindowEnd < @now and l.TbaWindowEnd = 0 )
AND ((ar.ID is not null) AND (ar.Ready = 1) AND (ar.CountryID = l.CountryID))
这个存储过程，在数据库上大量数据更新后（很多表和行受更新影响，但DB大小几乎没有变化，现在是752）变得非常慢。现在需要20到90秒。
如果我从存储过程中获取原始SQL查询 - 它将在1-2秒内执行。
我们尝试过：
使用参数
创建存储过程 SET ANSI_NULLS ON
使用参数with recompile
DBCC FREEPROCCACHE UPDATE STATISTICS Media WITH FULLSCAN 然而，存储过程的执行仍然是＆gt;＆gt; 30秒。
但是如果我运行由SP生成的SQL查询 - 它执行的时间不到2秒。
我已经比较了SP和原始SQL的执行计划 - 它们完全不同。在执行RAW SQL期间 - 优化器正在使用Merge Joins，但是当我们执行SP时 - 它使用Hash Match（内部连接），就像没有索引一样。
如果有人知道它会是什么 - 请帮忙。提前谢谢！
答案 0 :(得分：12)
尝试使用提示OPTIMIZE FOR UNKNOWN。如果它工作，这可能比每次强制重新编译更好。问题是，最有效的查询计划取决于所提供的日期参数的实际值。在编译SP时，sql server必须猜测将提供哪些实际值，并且可能在这里做出错误的猜测。 OPTIMIZE FOR UNKNOWN是针对这个确切的问题。
在查询结束时，添加
OPTION (OPTIMIZE FOR (@now UNKNOWN))
答案 1 :(得分：0)
由于您正在使用sp_executesql重新编译该过程，或者清除该过程的缓存计划实际上没有帮助，因此通过sp_executesql执行查询的查询计划
单独缓存到存储过程。
您需要将查询提示WITH (RECOMPILE)添加到执行的sql中，或者在执行之前清除该特定sql的缓存：
DECLARE @PlanHandle VARBINARY(64);
SELECT @PlanHandle = cp.Plan_Handle
FROM sys.dm_exec_cached_plans cp
CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS st
WHERE st.text LIKE '%' + @SQLString;
DBCC FREEPROCCACHE (@PlanHandle); -- CLEAR THE CACHE FOR THIS QUERY
EXECUTE sp_executesql @SQLString,@ParmDefinition, @MediaID, @Rfa, @LicenseWindow, @OwnerID, @LicenseType, @PriceGroupID, @Format, @GenreID,
@Title, @Actor, @ProductionCountryID, @DontReturnMoviesWithNoLicense,@DontReturnNotReadyMovies, @take, @skip, @now;
当你执行DBCC FREEPROCCACHE时，你没有传递任何参数并清除整个缓存，这当然无关紧要。