Union Transformation

The Union transformation is a multiple input group transformation that you use to merge data from multiple pipelines or pipeline branches into one pipeline branch. It merges data from multiple sources similar to the UNION ALL SQL statement to combine the results from two or more SQL statements. Similar to the UNION ALL statement, the Union transformation does not remove duplicate rows.

The Integration Service processes all input groups in parallel. It concurrently reads sources connected to the Union transformation and pushes blocks of data into the input groups of the transformation. The Union transformation processes the blocks of data based on the order it receives the blocks from the Integration Service.

You can connect heterogeneous sources to a Union transformation. The transformation merges sources with matching ports and outputs the data from one output group with the same ports as the input groups.

The Union transformation is developed using the Multigroup External Procedure transformation.

Union Transformation Rules and Guidelines

Use the following rules and guidelines when you work with a Union transformation:

You can create multiple input groups, but only one output group.

All input groups and the output group must have matching ports. The precision, datatype, and scale must be identical across all groups.

The Union transformation does not remove duplicate rows. To remove duplicate rows, you must add another transformation such as a Router or Filter transformation.

You cannot use a Sequence Generator or Update Strategy transformation upstream from a Union transformation.

The Union transformation does not generate transactions.