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Performance Issue

Aug 17, 2017 at 10:38 PM

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Hi Gurus,

I have a four queries each of which supplies data to the next. When I test each query as a stand alone object in a dataflow they each take about 300 seconds to run. When I daisy-chain them in sequence in a single dataflow they take about 7500 seconds. Clearly DS is doing something strange under the hood. Can anyone enlighten me as to the cause of this behavior and how to fix it?

Interestingly I was able to unify them into a single query (an eight table join) and it ran in the same time as the individual queries.

Thanks

Cliff

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1 Answer

Best Answer
Dirk Venken
Aug 18, 2017 at 03:49 PM
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Most probably, when you run them separately, DS pushes the logic to the underlying database.; when you chain them together, it doesn't.

See

https://blogs.sap.com/2014/02/13/let-the-database-do-the-hard-work-better-performance-in-sap-data-services-thanks-to-full-sql-pushdown/ for an explanation of those so-called SQL-pushdown mechanisms.

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