DBMS (Data Base Management System) play an important role in GIS by forming a link between spatial and aspatial data. DBMS provide access to data to multiple users at the same time, prevent loss of data and provide security access. Currently available DBMS are generally based on the hierarchical model, network model, relational model or their derivatives. Columns of the table are called attributes and all the values of an attribute describe the set of all possible values. Rows are also called records, tuples or relation elements.
However, the data model on which most relational DBMS are based do not meet the requirements of modern GIS. GIS integrate data from a variety of sources into a single homogeneous system and hence need powerful and flexible data models to meet the requirements of multiple tasks. For example:
However, the data model on which most relational DBMS are based do not meet the requirements of modern GIS. GIS integrate data from a variety of sources into a single homogeneous system and hence need powerful and flexible data models to meet the requirements of multiple tasks. For example:
- Sophisticated treatment of real world geometry
- Representation of data at different conceptual levels of resolution and detail
- management of history and versions of objects
- Combinations of measurements of different resolutions and accuracy
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