ABSTRACT
This chapter focuses on the database support that is required for a geographical information systems (GIS) that is used for design activities. Such activities have special requirements, including the management of more than one alternative plan and the handling of transactions with the system that are much more complex and lengthy than traditional database interactions. The chapter discusses the requirements for GIS as a design tool and consider how well traditional GIS databases meet these requirements. It presents background material on database consistency maintenance and version management. The copy-on-update principle used is one of the basic concepts used within our GIS version-managed data-store. Whenever a read access is issued, the version controller retrieves the most up-to-date version of the data accessible by that user, and whenever a write access is issued the version controller makes a copy of the record, updates it and amends all pointers to it.
