The transformation language includes a group of variable functions to update the current value of a mapping variable throughout the session. When you run a workflow, the PowerCenter Integration Service evaluates the start and current value of a variable at the beginning of the session based on the final value of the variable from the last session run. Use the following variable functions:
Use different variable functions with a variable based on the aggregation type of the variable.
When using mapping variables in sessions with multiple partitions, use variable functions to determine the final value of the variable for each partition. At the end of the session, the PowerCenter Integration Service performs the aggregate function across all partitions to determine one final value to save to the repository. Unless overridden, it uses the saved value as the start value of the variable for the next time you use this session.
For example, you use SetMinVariable to set a variable to the minimum evaluated value. The PowerCenter Integration Service calculates the minimum current value for the variable for each partition. Then at the end of the session, it finds the minimum current value across all partitions and saves that value into the repository.
Use SetVariable only once for each mapping variable in a pipeline. When you create multiple partitions in a pipeline, the PowerCenter Integration Service uses multiple threads to process that pipeline. If you use this function more than once for the same variable, the current value of a mapping variable may have indeterministic results.