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Planning "as late as possible" depending on successor element

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(@tjaeckle)
Posts: 15
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Début du sujet
 
[#2898]

Hello!
Following situation:
I plan a production. It should start, when all predecessors are finished.
For a very expensive part I would like to start ordering as late as possible. As successor for the ordering I entered the start of the production. I tried this with planning mode "as late as possible". Unfortunately this works only with an end date. But if planning changes, I would have to change the end date manually, very error prone.
Is there any way, that the ordering starts as late as possible with a reference date coming not from an input but from date of a successors?


 
Posté : 12 Jan PM 19:011
(@babynus)
Posts: 14952
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Without defining an end date, as late a possible woul plan to finish on 31/12/9999.
Ist'n it a bit too late ? 👿

But to really answer your Question, what you try to get is a start-end dependency.
This does not exist in Projeqtor, only end-start exists.


 
Posté : 12 Jan PM 21:011
(@tjaeckle)
Posts: 15
Active Member
Début du sujet
 

Hello Babynus,

Without defining an end date, as late a possible woul plan to finish on 31/12/9999.
Ist'n it a bit too late ? 👿

Well maybe it's too late for my boss, but it wouldn't be my problem any more. 😉

As such a planning method would be useful for many "just in time" problems:
Am I right, that such start-end-dependencies are not simple to implement?


 
Posté : 13 Jan AM 10:011
(@babynus)
Posts: 14952
Membre Admin
 

Am I right, that such start-end-dependencies are not simple to implement?

Yes, it's quite hard, moreover in the way ProjeQtOr calculates planning : without overloading resources.

For instance, imagine 2 tasks A->B, A as late as possible depending on B start, single resource R assigned to A and B.
In the way ProjeQtOr plans, it should start to plan B, to get start date. But this will use R availibiity, so leaving no more room to place A before; this would involve to plan A before B... unless B has a constraints pushing it a bit later in the planning.
But if now another resource S is assigned to A, problem may be completely different as S may have availability to work on A... or not (depending on other tasks).
And these are simple examples.
Taking into account all use cases will really be a mess and will possibly (I'm afraid it will) not give expected result in most cases.


 
Posté : 13 Jan PM 12:011
(@tjaeckle)
Posts: 15
Active Member
Début du sujet
 

It's a pity, but I see the problem.

Thanks


 
Posté : 13 Jan PM 12:011
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