Oracle7 Server Distributed Systems Volume II: Replicated Data

Overwrite and Discard Update Conflict Resolution Methods

The overwrite and discard methods ignore the values from either the originating or destination site and therefore can never guarantee convergence with more than one master site. These methods are designed to be used by a single master site and multiple snapshot sites, or with some form of a user-defined notification facility.

For example, if you have a single master site that you expect to be used primarily for queries, with all updates being performed at the snapshot sites, you might select the overwrite method. The overwrite and discard methods are also useful if:

your primary concern is data convergence

you have a single master site

there is no particular business rule for selecting one update over the other

or if

you have multiple master sites

you supply a notification facility to notify the person who ensures that data is correctly applied, instead of logging the conflict in the DefError view and leaving the resolution to your local database administrator

The overwrite routine replaces the current value at the destination site with the new value from the originating site. Conversely, the discard method ignores the new value from the originating site.