Difference between data mart and data warehouse

Incremental Aggregation

Using this, you apply captured changes in the source to aggregate calculation in a session. If the source changes only incrementally and you can capture changes, you can configure the session to process only those changes

This allows the sever to update the target incrementally, rather than forcing it to process the entire source and recalculate the same calculations each time you run the session.

Steps:

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 data