Filters between the originating and replicating systems perform rolling upgrades that involve database schema changes. The filters manipulate the data under the different schemas when the software revision levels on the systems differ.

GT.M provides the ability to invoke a filter; however, an application developer must write the filters specifically as part of each application release upgrade when schema changes are involved.

Filters should reside on the upgraded system and use logical database updates to update the schema before applying those updates to the database. The filters must invoke the replication Source Server (new schema to old) or the database replication Receiver Server (old schema to new), depending on the system's status as either originatig or replicating. For more information on Filters, refer to “Filters”.