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.

can anyone explain about incremental aggregation with an example?

 When you use aggregator transformation to aggregate it creates index              and data caches to store the data 1.Of group By columns 2. Of   aggreagte columns             the incremental aggreagtion is used when we have historical data in              place which will be used in aggregation incremental aggregation uses  the cache which contains the historical data and for each group by  column value already present in cache it add the data value to its             corresponding data cache value and outputs the row in case of a             incoming value having no match in index cache the new values for             group by and output ports are inserted into the cache .

What is the use of incremental aggregation? Explain me in brief with an example.

1) its a session option. when the informatica server performs cremental aggr. it passes new source data through the mapping and   uses historical chache data to perform new aggregation caluculations     incrementaly. for performance we will use it.

2) Incremental aggregation is in session properties i have 500 records    in my source and again i got 300 records if u r not using incremental aggregation what are calculation r using on 500 records  again that calculation will be done on 500+ 300 records if u r using  incremental aggregation calculation will be done one only what are  new records (300) that will be calculated dur to this one   performance will increasing.

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.