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why to use copy stage .....

Posted: Wed Jun 06, 2007 7:08 am
by ajay.prakash03
can my job performance will improve with the use of copy stage if my source and target is same db(db2)? anyone can tell me how?

Posted: Wed Jun 06, 2007 7:19 am
by DSguru2B
Copy stage, like its name, just makes copies of your input. It has nothing to do with your source and target. It will make copies regardless. Its performance is pretty good too.

Re: why to use copy stage .....

Posted: Wed Jun 06, 2007 9:54 am
by wenfei.chen
You can drop or change the order of columns. You can have extra copies for backup purpose.

Posted: Wed Jun 06, 2007 10:13 am
by Minhajuddin
But I don't think that adding a Copy stage between your DB Stages would improve Performance.

Posted: Wed Jun 06, 2007 11:26 am
by DSguru2B
Minhajuddin wrote:But I don't think that adding a Copy stage between your DB Stages would improve Performance.
Right. The copy stage is intended to make copies of the input stream. If that is not the intension then un-necessarily do not stick in any stage.

Posted: Wed Jun 06, 2007 9:12 pm
by ray.wurlod
A Copy stage that does nothing will be optimized out of the design when the score is composed.

While the Copy stage is not permitted to change or add data, it can do any or all of the following:
- re-order columns
- drop columns
- rename columns

Posted: Wed Jun 06, 2007 11:52 pm
by wannabexpert
If there is any enhancements in your job in the future this copy stage(placeholder) will be useful.i think it wont improve the performance of a job

Posted: Thu Jun 07, 2007 12:55 am
by ray.wurlod
A Copy stage with no output link is an excellent placeholder while you are effecting incremental design. It will consume all the rows sent into it and have nowhere to transfer them, so will simply discard them.