GEOG 868
Spatial Database Management

Introduction to Versioned Editing


Introduction to Versioned Editing

In the last lesson, you digitized streets from a set of Sanborn maps. Perhaps without realizing it, you were performing non-versioned editing. This editing model, also sometimes called the short transaction model, is typical of traditional non-spatial database systems and has the advantage of being simple to implement. It can be preferable to versioned editing in situations where it is important for edits to be available to users immediately or if the data are frequently accessed by non-Esri applications.

However non-versioned editing has a longer list of limitations and disadvantages that often makes versioned editing the more logical choice. Among these are:

  • inability to undo/redo individual edits. This is an even bigger problem in ArcGIS Pro versus ArcMap.  In ArcMap, because it employs the concept of an editing session, it is possible to quit out of an editing session without saving, but you lose all edits made since the last save. For example, if you make 9 good edits and make a mistake on the 10th, you either need to end the edit session without saving (and lose all 10 edits) or accept the mistake and go back and correct it. A workaround for this is to save edits frequently.  ArcGIS Pro, on the other hand, does not employ editing sessions.  Thus, if you make a mistake editing a non-versioned feature class in Pro, you have no way to roll back that edit.  You'll have no choice but to correct the error yourself. 
  • inability to edit complex data (e.g., feature classes participating in a topology or geometric network). Only simple features can be edited.
  • locking of features being edited. If a second user attempts to edit the same feature, ArcGIS desktop software will become unresponsive.
  • no mechanism for resolving conflicts when multiple users edit the same feature. Non-versioned editing is a "last save wins" environment.

The versioned editing, or long transaction, model addresses all of these issues. Editors of a versioned feature class are able to undo/redo individual edits and can perform edits on either simple or complex data. Different editors can perform edits to the same features because, as the name implies, all of the editors are working off of their own version of the data. As we'll see, mechanisms exist for merging changes made in different versions and resolving conflicts when they crop up.

As you might guess, versioned editing is especially useful for organizations that make frequent and/or complicated edits to their data. Land parcels are a classic example in that they are in a constant state of flux and require a great deal of care to delineate properly.

Versioned editing relies on the usage of delta tables (tables that track changes made to the base feature class). One good reason to avoid using a versioned editing workflow is that non-Esri applications are not built to work with the data in these delta tables. If your organization uses non-Esri tools to access your data, you may need to develop workarounds or live with the limitations of non-versioned editing.

With these introductory notes behind us, let's take a look at how versioned editing works.