CTE query in SQL Server : exit when one row exists in result - sql

Question

I'm writing a SQL Server procedure to optimize cut of bars. I haven't found yet the best method. Seems to be CTE request, but I'm stuck.
I try to write a stored procedure to optimize cut of bars. For my test, I have to cut 18 pieces (3 of 1000 mm, 3 of 1500 mm, 3 of 2500mm, 3 of 3500 mm, 3 of 4500 mm and 3 of 6000 mm), and I have 3 sizes of bars (5500mm, 7000mm and 8500mm).
After that, I generate every combination of bars with any cuts as possible.
I tried with a while loop and a temporary table, It takes me one hour and a half. But I think I can do better with a CTE request...
Now, I must generate every combination of many bars to have my 18 cuts. I made another CTE request, but I haven't find the way to stop recursivity when at least one combination has all the cuts. So, my request find over 150 millions combinations, with 8,9,10,11... bars. And it tries every loop with 18 bars. I want it to stop with 8 bars (I know it is the smallest bar count I need for my cuts). And it takes more than two days !
I have 2 temporary tables, on with my combination of bars (#COMBI_BARRE) with this structure : ID_ART : identity for article, COLOR, CUT_COMBI : a varchar concat the cut ID of the bar combination : 1-2-3-4..., NB_CUTSan integer to get the count of cuts in the bar, FIRST_CUT the smaller cut ID of the bar.
I have another temporary table #DET_BAR with the detail of my cuts, with 2 columns : ID_COMBI_BAR the bar combination ID and ID_CUT_STR, the cut ID in varchar (to avoid cast or convert in CTE for better performance).
I store the result in a table call Combi, with the ID_ART, the COLOR, a varchar column Combi who concat the the bar combination ID (1-2-3-4...), a varchar column COMBI_CUT who concat the ID_CUT (1-2-3-4-5...), NB_BAR the count of bar in the combination, NB_CUTS : the count of cuts in the combination, MAX_CUTS the total number of cut I must to for my article and color.
As it makes one loop per bar,I tried to add a exists clause to stop recursivity when the number of loop has at least one combination with all my cuts. I know I must not cut 10 bars if I can do it with 8. But I get an error "the recursive table has multiple reference'.
How can I make my request and avoid every loop ?
;WITH Combi (ID_ART, COLOR, COMBI, COMBI_CUT, NB_BAR, NB_CUTS, MAX_CUTS)
AS
( SELECT C.ID_ART,
C.COLOR,
'-' + ID_COMBI_BAR_STR + '-',
'-' + C.CUT_COMBI + '-',
1,
C.NB_CUTS,
ISNULL(MAXI.CUT_NUM,0)
FROM #COMBI_BARRE C with(nolock)
outer apply (select top 1 D.CUT_NUM
from #DEBITS D
where D.ID_ART = C.ID_ART
and D.COLOR= C.COLOR
order by D.NUM_OCC_DEB desc) MAXI
WHERE C.FIRST_CUT = 1
UNION ALL
SELECT C.ID_ART,
C.COLOR,
Combi.COMBI + ID_COMBI_BAR_STR + '-',
Combi.COMBI_CUT+ C.CUT_COMBI + '-',
Combi.NB_BAR+ 1,
Combi.NB_CUTS+ C.NB_CUTS,
Combi.MAX_CUTS
FROM #COMBI_BARRE C with(nolock)
INNER JOIN Combi on C.ID_ART = Combi.ID_ART
and C.COLOR= Combi.COLOR
where C.FIRST_CUT > Combi.NB_BAR
and Combi.NB_CUTS+ C.NB_CUTS<= Combi.MAX_CUTS
and NOT EXISTS(select * from #DET_BAR D with(nolock)
where D.ID_COMBI_BAR = C.ID_COMBI_BAR
and PATINDEX(D.ID_CUT_STR, Combi.COMBI_CUT) > 0)
and NOT EXISTS(select top 1 * from Combi Combi2 where Combi2.ID_ART = C.ID_ART and Combi2.COLOR = C.COLOR and Combi2.NB_CUTS = Combi2.MAX_CUTS)
)
select * from Combi

Answer 1

This is a variation of the bin packing problem. That search term might help you in the right direction.
Also, you can to go my Bin Packing page, which gives several approaches to the more simplified version of your problem.
A small warning: the linked article(s) don't use any (recursive) CTE, so they won't answer your specific CTE question.