The Data Integration Service generates and executes a SELECT statement based on the transformation logic for each transformation it can push to the database. Then, it reads the results of this SQL query and processes the remaining transformations.

You can configure a mapping to use source pushdown if the source and target reside in different databases. For example, if a mapping contains a Teradata source and an Oracle target, you can configure source pushdown to push some transformation logic for processing to the Teradata source.