Pushdown optimization increases 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 apply pushdown optimization, 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 query for each source that has transformation logic pushed down. The Data Integration Service can also generate an INSERT query if the target was pushed to the database. The Data Integration Service reads the results of the SQL queries and processes the remaining transformations in the mapping.
The Data Integration Service applies pushdown optimization to a mapping when you select the pushdown type in the mapping run-time properties.
You can select the following pushdown types:
None. Select no pushdown type for the mapping.
Source. The Data Integration Service tries to push down as much transformation logic as it can to the source database.
Full. The Data Integration Service pushes the full transformation logic to the source database.
You can also create a string parameter for the pushdown type and use the following parameter values: