Transformations are the objects in Informatica which creates, modifies or passes data to the defined target structures (tables, files or any other target).
The purpose of the transformation in Informatica is to modify the source data as per the requirement of target system. It also ensures the quality of the data being loaded into the target.
Informatica provides various transformations to perform specific functionalities.
For example, performing tax calculation based upon source data, data cleansing operation, etc. In transformations, we connect the ports to pass data to it, and transformation returns the output through output ports.
Classification of Transformation
Transformation is classified into two categories, one based on connectivity, and other based on the change in no of rows. First we will look the transformation based on connectivity.
Types of transformation based on connectivity
- Connected Transformations
- Unconnected Transformations
In Informatica, during mappings the transformations which are connected to other transformations are called connected transformations.
For example, Source qualifier transformation of Source table EMP is connected to filter transformation to filter employees of a dept.
Those transformations that are not connected to any other transformations are called unconnected transformations.
Their functionality is used by calling them inside other transformations like Expression transformation. These transformations are not part of the pipeline.
The connected transformations are preferred when for every input row, transformation is called or is expected to return a value. For example, for the zip codes in every row, the transformation returning city name.
The unconnected transformations are useful when their functionality is only required periodically or based upon certain conditions. For example, calculation the tax details if tax value is not available.
Types of transformations based on the change in no of rows
- Active Transformations
- Passive Transformations
Active Transformations are those who modifies the data rows and the number of input rows passed to them. For example, if a transformation receives ten number of rows as input, and it returns fifteen number of rows as an output then it is an active transformation. The data in the row is also modified in the active transformation.
Passive transformations are those who does not change the number of input rows. In passive transformations the number of input and output rows remain the same, only data is modified at row level.
In the passive transformation, no new rows are created, or existing rows are dropped.