1. An arrangement comprising: a processor; a plurality of satellite databases communicating with said processor, each storing data; and a materialized database, under control of said processor, that stores a union of the data stored in all of said satellite databases, where said processor includes a queue that stores updates in a global database schema that are sent from said satellite databases to said processor, and said processor further includes a controller that retrieves said updates from said queue, sends said updates to one or more of said satellite databases in a corresponding satellite database schema, and applies said updates to said materialized database, in order to maintain consistency among said satellite databases and said materialized database; where said materialized database also sends updates to said queue; where said controller retrieves an update from said queue and, sequentially, applies each retrieved update to an outbound filter of each of said satellite databases and to said materialized database, where for each of said outbound filters, said materialized database is a source database and said each of said satellite databases, respectively, is a target database; and where said controller applies said each update to said materialized database after said each update has been applied to all of said satellite databases.