combinality mode

[legendkiller]

What is the functionality of combinality mode in Advance tab of stage? Where it can be useful?

[Kirtikumar]

DS can combine multiple stages as a single process. You can use this mode if you want to decide the combining by your own.

The mode can have values: Auto, Combinable, Don't Combine.
Auto: let the DataStage decide whether to combine the stages
Combinable: Combine the operator with other stage if possible
Don't Combine: do not combine them at all

As multiple stages are running as a single process, sync overhead in stages is also minimized.

[kumar_s]

Hi,
May i know some of scenario in which we can use the diferent options.

regards
kumar

[DEVESHASTHANA]

Kirti,

Can u explain combinability mode in more detail,
What do you mean by combine the operator with other stage if possible,
Please explain this with some example,

Thanking you in anticipation,

Regards,
Devesh

[roy]

Hi,
It is in the manuals,but...
combine means try to combine what ever you can to 1 operator.
don't combine means leave all operators seperate as in the job design.
if you read between the lines you see that the later will probably get you better performance.

IHTH,

[vmcburney]

We usually leave it at the default combine mode for faster processing. The only time we change it is when a lookup and a transformer get combined and the reject behaviour becomes different to what we want. You can have a lookup stage with no reject link that sends rows down the transformer reject link before it reaches transformer processing.

[roy]

The logic behind not combining operators being faster can be explained via a simple "fill the pool" example.
let us say you want to fill your pool with water.
you have 2 choices:
1. use a single long but narrow hose
2. put many shorter but a lot wider hoses 1 after the other.

suposing you can thruput to maximum any hose caliber, what choice will get your pool filled up faster?
(assuming were not talking 1 pint pools aka bear glases )