SSAS provides Process Incremental as one of the processing options for cubes, measure groups and partitions.

Process Incremental is extremely useful to process facts having journal entries. In a journal fact, updates to existing fact records are balanced by a corresponding negative or positive journal entry. In Process Incremental mode, a SQL query has to be provided that could identify the records inserted into the fact journal since last cube process.

To get more information about what's Process Incremental, please refer to the link below.

https://bennyaustin.wordpress.com/2011/10/29/ssas-process-incremental/[/url]