Maximum recursion has been exhausted

问题:

I need an efficient way to pass in a parameter [StartingNumber] and to count from [StartingNumber] sequentially until I find a number that is missing.

I use the following sql to get the next number:

      DECLARE @StartOffset int
        SET  @StartOffset = 23
        ; With Missing as (
            select @StartOffset as N where not exists(
    select * from [QUEUE] where QueueNum = @StartOffset AND ismelutash = 1)
        ), Sequence as 
    (       select @StartOffset as N from [QUEUE] where QueueNum = @StartOffset 
            union all
            select b.QueueNum from [QUEUE] b inner join Sequence s 
on b.QueueNum = s.N + 1 and b.ismelutash = 1
        )
        select COALESCE((select N from Missing),(select MAX(N)+1 from Sequence))

It has been working for awhile but now when I run it I get 'The statement terminated. The maximum recursion 100 has been exhausted before statement completion.'

Anyone have any ideas? Thanks

EDIT:

I added maxrecursion but it just loads and doesn't return data:

DECLARE @StartOffset int
SET  @StartOffset = 50

DECLARE @isMelutash int
SET @isMelutash = 0


; With QueueFilters as (
    select queuenum from queue where ismelutash = 1
),  Missing as (
    select @StartOffset as N where not exists(select * from QueueFilters where queuenum = @StartOffset)
), Sequence as (
    select @StartOffset as N from QueueFilters  where queuenum = @StartOffset
    union all
    select b.queuenum from QueueFilters  b inner join Sequence s on b.queuenum = s.N + 1
)
select COALESCE((select N from Missing ),(select MAX(N)+1 from Sequence ) )
**OPTION(MAXRECURSION 150)**

回答1:

You could use the MAXRECURSION option in your current code

However, there is no need to recurse line by line (using Itzik Ben-Gan's method). This will detect cases where there are no rows on Queue with ismelutash = 1 too because it uses the Tally table as a reference sequence

;WITH
  Pass0 as (select 1 as C union all select 1), --2 rows
  Pass1 as (select 1 as C from Pass0 as A, Pass0 as B),--4 rows
  Pass2 as (select 1 as C from Pass1 as A, Pass1 as B),--16 rows
  Pass3 as (select 1 as C from Pass2 as A, Pass2 as B),--256 rows
  Pass4 as (select 1 as C from Pass3 as A, Pass3 as B),--65536 rows
  Pass5 as (select 1 as C from Pass4 as A, Pass4 as B),--4,294,967,296 rows
  Tally as (select row_number() over(order by C) as Number from Pass5)
 select TOP 1
    Number 
 from 
    Tally T
    LEFT JOIN   --corrected, oops.
    [QUEUE] Q ON T.Number = Q.QueueNum AND Q.ismelutash = 1
 where
    T.Number >= @StartOffset AND T.Number <= 1000000
    AND
    Q.QueueNum IS NULL
 ORDER BY
    T.Number

Edit:

Original code with MAXRECURSION hint at the end. This link is better too

      DECLARE @StartOffset int
        SET  @StartOffset = 23
        ; With Missing as (
            select @StartOffset as N where not exists(
    select * from [QUEUE] where QueueNum = @StartOffset AND ismelutash = 1)
        ), Sequence as 
    (       select @StartOffset as N from [QUEUE] where QueueNum = @StartOffset 
            union all
            select b.QueueNum from [QUEUE] b inner join Sequence s 
on b.QueueNum = s.N + 1 and b.ismelutash = 1
        )
        select COALESCE((select N from Missing),(select MAX(N)+1 from Sequence))
        OPTION (MAXRECURSION 0)

回答2:

I believe this is equivalent, and it doesn't use recursion:

    SELECT COALESCE(MIN(QueueNum)
        , (SELECT Max(QueueNum) + 1
            FROM [Queue] 
            WHERE QueueNum > @StartOffset)
        , @StartOffset)
    FROM [QUEUE]
    WHERE QueueNum >= @StartOffset
    AND ismelutash != 1