Track modifications

AVEVA Historian tracks modifications (inserts, updates, and deletions) to columns in the Runtime database. If your plant tracks changes for compliance with regulatory agencies, you can configure the Historian to use modification tracking.

Modification tracking is system-wide; it is controlled by the ModLogTrackingStatus system parameter. You cannot turn modification tracking on or off at a table level. Enabling modification tracking decreases the Historian's performance when making changes to the system. This is due to the extra work and space required to track the changes. However, there is no performance degradation during run-time operation.

Information in the modification tracking tables are stored in the data files of the Microsoft SQL Server database. If modification tracking is turned on, the amount of data that is stored in these files is greatly increased.

All of the objects for which modifications can be tracked are stored in the HistorianSysObjects table.

You can track changes to configuration data. For example, additions or changes to tag, I/O Server, and storage location definitions. For more information, see About modification tracking for configuration changes.

Note: Changes to history data are tracked through an internal stored procedure called aaInternalHistoryModTrack. It captures the data modification with History view.

The types of changes that will be tracked is controlled by the ModLogTrackingStatus system parameter. You can track inserts, updates, and deletes, as well as various combinations. For more information, see Turn modification tracking on/off.