This classification of transformations is based on the number of records in the input and output port of the transformation. This classification is not based on the number of ports or the number of groups.

If the transformation does not change the number of records in its input and output ports, it is said to be a passive transformation. If the transformation changes the number of records in the input and output ports of the transformation, it is said to be an active transformation. Also, if the transformation changes the sequence of records passing through it, it is classed as an active transformation, as with Union transformations. Let's take an example to understand this classification.

Consider the Expression transformation from the mapping we used in the example of Expression transformations, where we concatenated FIRST_NAME and LAST_NAME, as shown in the following screenshot:

As you can see, the number of input ports is seven and the number of output ports is five. Say our source contains 10 records in the mapping. When we pass all the records to the transformation, the total records that will reach the input ports will be 10 and the total records that will reach the output ports will also be 10, so this makes Expression transformation passive. We are not concerned about the number of ports in the input and output.

Consider the example of filter transformations that filter out unwanted records, as this changes the number of records, it is an active transformation.

A transformation is said to be connected if it is connected to any source, target, or any other transformation by at least one link. If the transformation is not connected by any link, it it classified as unconnected. Only the lookup and Stored Procedure transformations can be connected and unconnected, all other transformations are connected.