Pushdown optimization improves mapping performance when the source database can process transformation logic faster than the Data Integration Service. The Data Integration Service also reads less data from the source.

The amount of transformation logic that the Data Integration Service pushes to the source database depends on the database, the transformation logic, and the mapping configuration. The Data Integration Service processes all transformation logic that it cannot push to a database.

When you configure pushdown optimization for the mapping, the Data Integration Service analyzes the optimized mapping from the source to the target or until it reaches a downstream transformation that it cannot push to the source database. The Data Integration Service generates and executes a SELECT statement for each source that has transformation logic pushed down. Then, it reads the results of this SQL query and processes the remaining transformations in the mapping.