Check my blog
Let the database do the hard work! Better performance in SAP Data Services thanks to full SQL-Pushdown, and more particularly the comment I posted on 18 Feb 2014:
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In, general, I do not recommend the use of SQL-transforms to our customers. Why would you want to hand-code something yourself that can be automatically generated by the tool?
Also, with SQL-transform as a source, DS cannot generate a full SQL-pushdown anymore. It will have to pull all data in memory before writing out to the target, not good for performance with high data volumes.
On top of that, it will break lineage and impact analysis functionality. Making your application maintenance more complex.
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