what is incremantal aggregation?

1) When using incremental aggregation, you apply captured changes in the 

source to aggregate calculations in a session.

 2) If the source changes only incrementally and you can capture changes, 

you can configure the session to process only those changes. 

3) This allows the Informatica Server to update your target incrementally,

 rather than forcing it to process the entire source and recalculate the 

same calculations each time you run the session.