How to use incremental aggregation in real time?

The first time you run a session with incremental aggregation  enabled the server process the entire source.
At the end of the session the server stores aggregate data from that session ran in   two files the index file and data file.
 The server creates the file in local directory.The second time you run the session use only  changes in the source as source data for the session.
 The server  then performs the following actions:For each input record the   session checks the historical information in the index file for a corresponding group then:If it finds a corresponding group – The
            server performs the aggregate operation incrementally using the  aggregate data for that group and saves the incremental changes.
Else  Server create a new group and saves the record dataWhen writing to  the target the server applies the changes to the existing target.
Updates modified aggregate groups in the targetInserts new  aggregate dataDelete removed aggregate dataIgnores unchanged      aggregate dataSaves modified aggregate data in Index/Data files to  be used as historical data the next time you run the session.
Each Subsequent time you run the session with incremental aggregation you use only the incremental source changes in the session.
If the source changes significantly and you want the server to continue saving the  aggregate data for the future incremental changes configure the   server to overwrite existing aggregate data with new aggregate data.