What is a Transformation in Informatica

A transformation is a repository object that generates, modifies, or passes data. The Designer provides a set of transformations that perform specific functions. For example, an Aggregator transformation performs calculations on groups of data.

Transformations in a mapping represent the operations the Informatica Server performs on the data. Data passes into and out of transformations through ports that you connect in a mapping or mapplet.

Transformations can be active or passive. An active transformation can change the number of rows that pass through it, such as a Filter transformation that removes rows that do not meet the configured filter condition. A passive transformation does not change the number of rows that pass through it, such as an Expression transformation that performs a calculation on data and passes all rows through the transformation.

Transformations can be connected to the data flow, or they can be unconnected. An unconnected transformation is not connected to other transformations in the mapping. It is called within another transformation, and returns a value to that transformation

Transformation Descriptions
Transformation	Type	Description
Advanced External Procedure	Active/ Connected	Calls a procedure in a shared library or in the COM layer of Windows NT.
Aggregator	Active/ Connected	Performs aggregate calculations.
ERP Source Qualifier	Active/ Connected	Represents the rows that the Informatica Server reads from an ERP source when it runs a session.
Expression	Passive/ Connected	Calculates a value.
External Procedure	Passive/ Connected or Unconnected	Calls a procedure in a shared library or in the COM layer of Windows NT.
Filter	Active/ Connected	Filters records.
Input	Passive/ Connected	Defines mapplet input rows. Available only in the Mapplet Designer.
Joiner	Active/ Connected	Joins records from different databases or flat file systems.
Lookup	Passive/ Connected or Unconnected	Looks up values.
Normalizer	Active/ Connected	Normalizes records, including those read from COBOL sources.
Output	Passive/ Connected	Defines mapplet output rows. Available only in the Mapplet Designer.
Rank	Active/ Connected	Limits records to a top or bottom range.
Sequence Generator	Passive/ Connected	Generates primary keys.
Source Qualifier	Active/ Connected	Represents the rows that the Informatica Server reads from a relational or flat file source when it runs a session.
Router	Active/ Connected	Routes data into multiple transformations based on a group expression.
Stored Procedure	Passive/ Connected or Unconnected	Calls a stored procedure.
Update Strategy	Active/ Connected	Determines whether to insert, delete, update, or reject records.
XML Source Qualifier	Passive/ Connected	Represents the rows that the Informatica Server reads from an XML source when it runs a session.