The Aggregator
transformation allows you to perform aggregate calculations, such as averages
and sums. The Aggregator transformation is unlike the Expression
transformation, in that you can use the Aggregator transformation to perform
calculations on groups. The Expression transformation permits you to perform
calculations on a row-by-row basis only.
When using the
transformation language to create aggregate expressions, you can use
conditional clauses to filter records, providing more flexibility than SQL
language.
The Informatica
Server performs aggregate calculations as it reads, and stores necessary data
group and row data in an aggregate cache.
After you create a
session that includes an Aggregator transformation, you can enable the session
option, Incremental Aggregation. When the Informatica Server performs
incremental aggregation, it passes new source data through the mapping and uses
historical cache data to perform new aggregation calculations incrementally.
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