Use the following guidelines when you configure the session for incremental aggregation:
Verify the location where you want to store the aggregate files.
The index and data files grow in proportion to the source data. Be sure the cache directory has enough disk space to store historical data for the session.
When you run multiple sessions with incremental aggregation, decide where you want the files stored. Then, enter the appropriate directory for the process variable, $PMCacheDir, in the Workflow Manager. You can enter session-specific directories for the index and data files. However, by using the process variable for all sessions using incremental aggregation, you can easily change the cache directory when necessary by changing $PMCacheDir.
Changing the cache directory without moving the files causes the Integration Service to reinitialize the aggregate cache and gather new aggregate data.
In a grid, Integration Services rebuild incremental aggregation files they cannot find. When an Integration Service rebuilds incremental aggregation files, it loses aggregate history.
Verify the incremental aggregation settings in the session properties.
You can configure the session for incremental aggregation in the Performance settings on the Properties tab.
You can also configure the session to reinitialize the aggregate cache. If you choose to reinitialize the cache, the Workflow Manager displays a warning indicating the Integration Service overwrites the existing cache and a reminder to clear this option after running the session.
You cannot use incremental aggregation when the mapping includes an Aggregator transformation with Transaction transformation scope. The Workflow Manager marks the session invalid.