带有选项的无限循环CTE（最大递归0）

Question

我有大量记录的CTE查询。以前它工作正常。但是最近，它对某些成员抛出了错误声明终止。在语句完成之前，最大递归100已用尽。因此，我提出OPTION (maxrecursion 0)或接受OPTION (maxrecursion 32767)查询，因为我不想限制记录。但是，结果是查询需要永远加载。我该如何解决？这是我的代码：with cte as(-- Anchor member definition    SELECT  e.SponsorMemberID , e.MemberID, 1 AS Level    FROM tblMember AS e     where e.memberid = @MemberIDunion all-- Recursive member definition    select child.SponsorMemberID , child.MemberID, Level + 1    from tblMember child join cte parenton parent.MemberID = child.SponsorMemberID)-- Select the CTE result    Select distinct a.*     from cte a    option (maxrecursion 0)

Answer 1

如果您要达到递归限制，那么您可能在赞助关系或数据循环方面有相当大的深度。如下所示的查询将检测循环并终止递归：

declare @tblMember as Table ( MemberId Int, SponsorMemberId Int );

insert into @tblMember ( MemberId, SponsorMemberId ) values

  ( 1, 2 ), ( 2, 3 ), ( 3, 5 ), ( 4, 5 ), ( 5, 1 ), ( 3, 3 );

declare @MemberId as Int = 3;

declare @False as Bit = 0, @True as Bit = 1;

with Children as (

  select MemberId, SponsorMemberId,

    Convert( VarChar(4096), '>' + Convert( VarChar(10), MemberId ) + '>' ) as Path, @False as Loop

    from @tblMember

    where MemberId = @MemberId

  union all

  select Child.MemberId, Child.SponsorMemberId,

    Convert( VarChar(4096), Path + Convert( VarChar(10), Child.MemberId ) + '>' ),

    case when CharIndex( '>' + Convert( VarChar(10), Child.MemberId ) + '>', Path ) = 0 then @False else @True end

    from @tblMember as Child inner join

      Children as Parent on Parent.MemberId = Child.SponsorMemberId

    where Parent.Loop = 0 )

  select *

    from Children

    option ( MaxRecursion 0 );

Answer 2

因此问题不是来自maxrecursion。来自CTE。我不知道为什么，但是可能包含任何赞助者周期：A-> B-> C-> A-> ...（