Union transformation

Union transformation is used to the merge data from multiple sources. A union is a multiple-input-single-output transformation. This is the opposite of the router transformation that we discussed earlier. The basic criterion for using union transformation is that you should have data with matching data type. If you do not have data with matching data type coming from multiple sources, union transformation will not work. Union transformation merges the data coming from multiple sources and does not remove duplicates, that is. it acts as UNION ALL of SQL statements.

As mentioned previously, Union requires data coming from multiple sources. It reads the data concurrently from multiple sources and processes the data. You can use heterogeneous sources to merge the data using Union transformation.

A mapping indicating the Union transformation is shown in the following screenshot:

Working on Union transformation is a little different from working on other transformations, which...