After you run an incremental aggregation session, avoid moving or modifying the index and data files that store historical aggregate information.
If you move the files into a different directory, and you want the Integration Service to use the aggregate files, you must also change the path to those files in the session properties. As well, if you change the path to the files, but you do not move the files, the Integration Service rebuilds the files the next time you run the session.
If you change certain session or Integration Service properties, the Integration Service cannot use the incremental aggregation files, and it fails the session. To avoid session failure, delete existing incremental aggregation files when you perform any of the following tasks:
Change the Integration Service data movement mode from ASCII to Unicode or from Unicode to ASCII.
Change the Integration Service code page to an incompatible code page.
Change the session sort order when the Integration Service runs in Unicode mode.
Change the Enable High Precision session option.