Infinite loop CTE with OPTION (maxrecursion 0)

问题:

I have CTE query with large record on it. Previously it worked fine. But lately, it throws an error for some members

The statement terminated. The maximum recursion 100 has been exhausted before statement completion.

So I put OPTION (maxrecursion 0) or OPTION (maxrecursion 32767) on my query, because I don't want to limit the records. But, the result is the query takes forever to load. How do I solve this?

Here's my code:

with cte as( -- Anchor member definition     SELECT  e.SponsorMemberID , e.MemberID, 1 AS Level     FROM tblMember AS e      where e.memberid = @MemberID  union all  -- Recursive member definition     select child.SponsorMemberID , child.MemberID, Level + 1     from tblMember child   join cte parent  on parent.MemberID = child.SponsorMemberID ) -- Select the CTE result     Select distinct a.*      from cte a     option (maxrecursion 0) 

EDIT: remove unnecessary code to easy understand

SOLVED: So the issue is not came from maxrecursion. It's from the CTE. I don't know why but possibly it contain any sponsor cycles: A -> B -> C -> A -> ... (Thanks to @HABO)

I tried this method and it works. Infinite loop in CTE when parsing self-referencing table

回答1:

If you are hitting the recursion limit, you either have considerable depth in sponsoring relationships or a loop in the data. A query like the following will detect loops and terminate the recursion:

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 ); 

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