An arrangement maintains consistency among satellite databases and an integrated database that is the union of the satellite databases with a controller that fetches update requests from a queue and applies each fetched request to all of the databases, in sequence, ending with the integrated database. In applying a modification request to a target database, a filter is used that comprises two components. The first component processes the modification request submitted by the queue to a modification request that is appropriate for the schema of the target database and that is based on the data that is already present in the target database. When appropriate, the first component also creates an update request that is sent to the queue, to achieve transitive closure. The second component communicates with the target database, using the API and protocols of the target database.