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Performance gains by combining Lookups ???
Posted: Mon Feb 25, 2008 10:23 am
by tomengers
Hi Gang ...
I have a PX job with 3 Lookups - the reference file for each is a DataSet. Are there performance gains to be relized by combining these 3 Lookups into one Stage? ... or will the Optimizer do that for me?
thanks ...
... tom
Re: Performance gains by combining Lookups ???
Posted: Mon Feb 25, 2008 11:21 am
by priyadarshikunal
tomengers wrote:Hi Gang ...
I have a PX job with 3 Lookups - the reference file for each is a DataSet. Are there performance gains to be relized by combining these 3 Lookups into one Stage? ... or will the Optimizer do that for me?
thanks ...
... tom
why dont you try both the options and let us know what the result is.
The DataStage optimizer combines the operators as much as possible.
not necessary that it will combine all the operators.
To know the difference try both option and let us know the timings and score.
Regards,
Posted: Mon Feb 25, 2008 3:54 pm
by ray.wurlod
If the Lookup (and any other) stages are adjacent, use the same degree of parallelism and combinable, then their operators will be combined into one process. Therefore the answer to you question is likely to be "no".