[Informatica] Union Transformation

Union Transformation

::Transformation type::
Connected
Active

::Use::
Union Transformation is used to merge data form multiple pipeline to form a single pipeline. All the rows from all the input pipelines pass though the Union Transformation. Its noteworthy that Union Transformation DOES NOT remove duplicates. This makes Union a Active transformation. You can Union as many pipelines / sources in a single Union Transformation. However, such is not the case with a Join Transformation.

::Union Groups::
-    As soon as you add a single input pipeline / source to the Union Transformation. The Designer automatically adds output ports groups to the Union Transformation. One cannot edit/delete the output port.
-    The Groups tab displays the Input groups. All the input pipelines appear in this tab. One can rename the groups based on their convention. 
-    The Group Ports displays the column name along with datatype, scale and precision. 

::Rules::
-    The participating sources in a Union must have same number of columns.
-    The datatype, precision and scale for the input ports must match exactly.
-    As discussed earlier, Union Transformation is similar to Union All operation and does not remove duplicate values. However, to do so, you can add a Filter Transformation or alternatively a Router Transformation.

::Note::
-    If you connect all ports in one input group, but do not connect a port in another input group, the PowerCenter Server passes NULLs to the unconnected port.
- One can join heterogeneous sources to the Union Transformation ie. a Flat file, Table etc to form a single pipeline. The only condition is to keep the number of columns, datatype and precision the same.

::Example::
The following example shows union of table1 and table2 with diffrent tabs for Uniion transformation.
The below image highlights how a new group can be added and renamed.