The Union transformation is an active transformation with multiple input groups and one output group. It merges sources with matching ports, and it passes data through an output group that has the same port structure as the input groups. Use a Union transformation in the Developer tool to merge data from multiple sources without removing the duplicate rows.

For example, you want to combine customer account data from American Bank and California Bank. You can create a mapping that contains a Union transformation to merge data from the source objects and write to a target object.

The following figure shows a mapping with a Union transformation: