Use filters early in the data flow to improve mapping performance.
Use one of the following transformations to filter data:
•Source transformation. The Source transformation filters rows from database or data warehouse sources.
•Filter transformation. The Filter transformation filters data within a mapping. The Filter transformation filters rows from any type of source.
If you filter rows from the mapping, you can improve efficiency by filtering early in the data flow. Use a filter in the Source transformation to remove the rows at the source. The Source transformation limits the row set extracted from a database or data warehouse source.
If you can't use a filter in the Source transformation, use a Filter transformation and move it as close to the Source transformation as possible to remove unnecessary data early in the data flow. The Filter transformation limits the row set sent to a target.
Avoid using complex expressions in filter conditions. To optimize Filter transformations, use simple integer or true or false expressions in the filter condition.