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Custom Transformation
Custom transformations operate in conjunction with procedures you create outside of the Designer interface to extend PowerCenter functionality. You can create a Custom transformation and bind it to a procedure that you develop using the Custom transformation functions. Use the Custom transformation to create transformation applications, such as sorting and aggregation, which require all input rows to be processed before outputting any output rows. To support this process, the input and
output functions occur separately in Custom transformations compared to External Procedure transformations.
The Integration Service passes the input data to the procedure using an input function. The output function is a separate function that you must enter in the procedure code to pass output data to the Integration Service. In contrast, in the External Procedure transformation, an external procedure function does both input and output, and its parameters consist of all the ports of the transformation
output functions occur separately in Custom transformations compared to External Procedure transformations.
The Integration Service passes the input data to the procedure using an input function. The output function is a separate function that you must enter in the procedure code to pass output data to the Integration Service. In contrast, in the External Procedure transformation, an external procedure function does both input and output, and its parameters consist of all the ports of the transformation
Aggregator Transformation
The Aggregator transformation performs aggregate calculations, such as averages and sums. The Integration Service performs aggregate calculations as it reads and stores data group and row data in an aggregate cache.The Aggregator transformation is unlike the Expression transformation, in that you use the Aggregator transformation to perform calculations on groups. The Expression transformation permits you to perform calculations on a row-by-row basis.
When you use the transformation language to create aggregate expressions, you can use conditional clauses to filter rows, providing more flexibility than SQL language.
After you create a session that includes an Aggregator transformation, you can enable the session option, Incremental Aggregation. When the Integration Service performs incremental aggregation, it passes source data through the mapping and uses historical cache data to perform aggregation calculations incrementally.
When you use the transformation language to create aggregate expressions, you can use conditional clauses to filter rows, providing more flexibility than SQL language.
After you create a session that includes an Aggregator transformation, you can enable the session option, Incremental Aggregation. When the Integration Service performs incremental aggregation, it passes source data through the mapping and uses historical cache data to perform aggregation calculations incrementally.
Working with Transformations
Transformations Overview
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 Integration Service performs on the data. Data passes through transformation ports that you link in a mapping or mapplet. Transformations can be active or passive. Transformations can be connected to the data flow, or they can be unconnected.
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 Integration Service performs on the data. Data passes through transformation ports that you link in a mapping or mapplet. Transformations can be active or passive. Transformations can be connected to the data flow, or they can be unconnected.
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