A spatial database is defined as a collection of inter-related geodspatial data, that can handle and maintain a large amout of data which is shareable between different GIS applications.
Required functions of a spatial database are as follows.
- consistency with little or no redundancy
- maintenance of data quality including updating
- self descriptive with metadata
- high performance by database mangement system with database langauage
- security including access control
In 1980's, GIS institution was centralized with a centralized spatial database. But in 1990's, the network concept arose, whice will be more convenient to meet user needs with distributed databases as shown in Figure 4.1. Such distributed databases in a network structure have the following benefits.
- better data storage and updating
- more efficient retrieval
- more efficient output