TSQL优化多个相交

Question

问题查询使用多个相交。

使用count（）= 6将它更改为in（'alpha'，'beta'，'gamma'，'delta'，'epsilon'，'phi'）组不是一个选项，因为应用程序支持像通配符（如alpha％）。但count（）= 6查询在少于1秒内运行。

使用通配符可以使用多个连接，这就是它的结构。在4或更少的情况下，相交表现比多重联结更好，但不幸的是没有测试5或更多。

查询对任何4个术语表现都很好 - 少于1秒。
字面上任何4 - 前4，后4或中4 4.
5或更多，然后它死了 - 我在2分钟杀死查询。
在6个术语让它运行 - 5分钟返回795行。

最多4个术语查询计划将循环与合并连接进行混合。
在5个或更多的术语中，查询计划都是循环连接。
是否有将查询提示应用于相交的语法？

尝试了两套使用（）（）但没有更改查询计划的3套。

(-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'alpha') 
) -- end term 
INTERSECT 
    (-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'beta') 
) -- end term 
INTERSECT 
    (-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'gamma') 
) -- end term 
INTERSECT 
    (-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'delta') 
) -- end term 
INTERSECT 
    (-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'epsilon') 
) -- end term 
INTERSECT 
    (-- start term 
     select [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     where [ftsIndexWordOnce].[wordID] in ( 
      select [id] from [FTSwordDef] with (nolock) 
            where [word] like 'phi') 
) -- end term 

认为我有一个修复

 select distinct [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     Inner Merge Join [FTSwordDef] with (nolock) 
     On [FTSwordDef].[ID] = [ftsIndexWordOnce].[wordID] 
     And [FTSwordDef].[word] like 'alpha' 
    INTERSECT 
    select distinct [ftsIndexWordOnce].[sID] 
     from [ftsIndexWordOnce] with (nolock) 
     Inner Merge Join [FTSwordDef] with (nolock) 
     On [FTSwordDef].[ID] = [ftsIndexWordOnce].[wordID] 
     And [FTSwordDef].[word] like 'beta' 

查询优化器还是那张愚蠢的在5个以上，但是这会强制先加入是合并，并将其保存。

Answer 1

可能想尝试“存在”。 “IN”可能会变得昂贵，特别是对于大型列表。 “EXISTS”只是寻找第一场比赛，而“IN”则试图找到他们。如果sID在ftsIndexWordOnce中是唯一的，则下面的代码应该可以工作。如果没有，你可以添加不同的或组。

编辑：第一个脚本有逻辑错误。看评论。

SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'alpha' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    ) 
INTERSECT 
SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'beta' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    ) 
INTERSECT 
SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'gamma' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    ) 
INTERSECT 
SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'delta' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    ) 
INTERSECT 
SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'epsilon' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    ) 
INTERSECT 
SELECT 
    [ftsIndexWordOnce].[sID] 
FROM 
    [ftsIndexWordOnce] WITH (NOLOCK) 
WHERE 
    EXISTS 
    (
     SELECT 
      NULL 
     FROM 
      [FTSwordDef] WITH (NOLOCK) 
     WHERE 
      [FTSwordDef].[word] LIKE 'phi' 
      AND 
      [FTSwordDef].id = [ftsIndexWordOnce].wordid 
    )