Use one of the following transformations to filter data:
Source Qualifier transformation.
The Source Qualifier transformation filters rows from relational sources.
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 Qualifier transformation to remove the rows at the source. The Source Qualifier transformation limits the row set extracted from a relational source.
If you cannot use a filter in the Source Qualifier transformation, use a Filter transformation and move it as close to the Source Qualifier 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/false expressions in the filter condition.
You can also use a Filter or Router transformation to drop rejected rows from an Update Strategy transformation if you do not need to keep rejected rows.