tsql - contains 和 containstable 之间有显着区别吗？

Question

我在启用了文件流的 varchar(max) 类型列上创建了全文索引。文件流包含 JPG、TIF、PDF 和 XML 等数据(尽管我认为这与问题大多无关)。

我创建了两个查询，允许我在索引上进行搜索。

全文搜索#1--

select
      parentObj.ObjectID as 'GroupingID',
      parentObj.Name as 'Grouping',
      childObj.ObjectID as 'FileObjID', 
      childObj.Name as 'FileName',
      fs.FileStreamID
    from dbo.dat_FileStream fs
    inner join dbo.dat_Object childObj
        on fs.ObjectID = childObj.ObjectID
    inner join dbo.dat_Collection c
        on fs.ObjectID = c.ObjectID
    inner join dbo.dat_Object parentObj
        on c.ParentID = parentObj.ObjectID
    where contains(FileStreamData, @srchTerm)
        and parentObj.ObjectTypeID = 1
    ORDER BY 'Grouping'

全文搜索#2--

select
      KEY_TBL.RANK,
      parentObj.ObjectID as 'GroupingID',
      parentObj.Name as 'Grouping',
      childObj.ObjectID as 'FileObjID',
      childObj.Name as 'FileName',
      fs.FileStreamID
    from dbo.dat_FileStream fs
    inner join containstable(dbo.dat_FileStream, FileStreamData, @srchTerm, 1000) as KEY_TBL
        on fs.FileStreamID = KEY_TBL.[KEY]
    inner join dbo.dat_Object childObj
        on fs.ObjectID = childObj.ObjectID
    inner join dbo.dat_Collection c
        on fs.ObjectID = c.ObjectID
    inner join dbo.dat_Object parentObj
        on c.ParentID = parentObj.ObjectID
    where parentObj.ObjectTypeID = 1
    ORDER BY 'Grouping'

两个全文搜索之间唯一显着的区别是查询 #1 使用 contains，而查询 #2 使用 containstable。

我的问题是两个查询并不总是产生相同的结果。例如，如果我搜索短语“独立承包商”，查询 #1 将生成 10 个不同文档(PDF 和 XML)的结果集，而查询 #2 将仅生成 6 个结果集。这似乎是规则:查询 #1 总是比查询 #2 产生更多的结果，而查询 #2 总是产生与查询 #1 完全相同的匹配项。

查询#1 - 搜索“独立承包商”结果:

4262    AAA-00-12   4561    AAA-00-12.pdf   4235
4316    AAA-00-15   4753    AAA-00-15.pdf   4427
4316    AAA-00-15   4754    AAA-00-15.xml   4428
3873    AAA-00-19   4784    AAA-00-19.pdf   4458
3903    AAA-00-22   6795    AAA-00-22.pdf   6459
3953    AAA-00-24   6899    AAA-00-24.pdf   6563
3953    AAA-00-24   6900    AAA-00-24.xml   6564
4842    AAA-00-9    4905    AAA-00-9.pdf    4577
4842    AAA-00-9    4906    AAA-00-9.xml    4578
4057    AAA-0001    4260    AAA-0001.pdf    3936

查询 #2 - 搜索“独立承包商”结果:

19  4262    AAA-00-12   4561    AAA-00-12.pdf   4235
126 4316    AAA-00-15   4754    AAA-00-15.xml   4428
126 4316    AAA-00-15   4753    AAA-00-15.pdf   4427
116 3873    AAA-00-19   4784    AAA-00-19.pdf   4458
125 3903    AAA-00-22   6795    AAA-00-22.pdf   6459
57  3953    AAA-00-24   6900    AAA-00-24.xml   6564
57  3953    AAA-00-24   6899    AAA-00-24.pdf   6563

Answer 1

CONTAINSTABLE :

top_n_by_rank

Specifies that only the nhighest ranked matches, in descending order, are returned. Applies only when an integer value, n, is specified. If top_n_by_rank is combined with other parameters, the query could return fewer rows than the number of rows that actually match all the predicates.

尝试在没有顶部的情况下运行，看看它是否匹配CONTAINS。