Archiving in ArcGIS provides the functionality to record and access changes made to all or a subset of data in a versioned geodatabase. Geodatabase archiving is the mechanism for capturing, managing, and analyzing data change.
Organizations need to preserve the changes made to their data in order to answer common questions, such as
- What was the value for a specific attribute at a certain moment?
- How has a particular feature or row changed through time?
- How has a spatial area evolved over time?
Geodatabase archiving assists the organization in answering these types of questions by preserving data changes. It is important to understand that geodatabase archiving maintains change from the moment archiving is enabled until archiving is disabled.
Previous geodatabase archiving solutions relied on the creation of versions to capture historical snapshots of the entire database. However, once the data is unversioned or the version deleted, the historical representation of the data is lost.
Geodatabase archiving introduces a historical version in addition to the existing transactional version. Users connect to either a transactional version or a historical version. A transactional version allows users to edit the data. A historical version represents the data at a specific moment in time and provides a read-only representation of the geodatabase. One can connect to a historical version using an existing historical marker or a specified moment. A historical marker is a named moment in time that you create, for example,"Completion of Subdivision 158" referencing the date 2:13 PM July 11, 2006.
The archiving model supports the complete geodatabase data model. Stand-alone feature classes, feature datasets, tables, relationship classes, networks, topologies, and terrains can all participate in archiving. Archiving requires the data to be registered as versioned. Once archiving is enabled, all changes saved or posted to the DEFAULT version are maintained in the corresponding archive class. The archive class is a complete copy of the archive enabled class plus all the edits that have been saved or posted to the DEFAULT version.
Tools available in ArcGIS offer users the ability to easily investigate change to the data. The History Viewer tool allows users to quickly navigate to specific moments in time for displaying how the data appeared at that moment. Additionally, adding the archive class directly to ArcMap allows users to perform queries to explore how the data has evolved over time. For example, view all the edits that have occurred to a specific road between Jan 18, 2006, and July 1, 2006.