Research And Implementation Of Data Model And Query Language In Spatio-temporal Databases

Spatio-temporal databases is the research hotspot on the basis of spatial databases and temporal databases, which is mainly used for processing discrete or continuous changes with time in spatial objects, and the cores are spatio-temporal objects data model, storage structure and topological analysis operations, with the aim to provide a highly reliable and efficient software platform for analysis and decision making of spatio-temporal information. Many key issues about spatio-temporal databases are discussed profoundly in this paper, as follows.On the basis of discussing the core issues of spatio-temporal databases, through the use of spatio-temporal data modeling based on the data type, from the abstract level to the discrete level, a complete spatio-temporal data types system is provided, and two new types are proposed,enriches the expressive power of the original types system. The first type which can support the both past and future movements of spatio-temporal objects, fully support full-time queries, and resolve that the prior data type could not support the past and future movements at same time. The second type spatio-temporal composite type which can support fractal in the movement life of spatio-temporal objects, can represent more complex spatio-temporal objects, and resolve that a data type can only describe a topological object.According to proposed spatio-temporal data types, the implementation of core data structure is given. In order to support different types of queries effectively, two kinds of storage structures are used which are spatio-temporal snapshots by sequence and two-level balanced binary tree(AVL-tree) at the same time. On this basis, one typical algorithm is presented.Based on O-RDBMS AMOSII expansion enabling spatio-temporal database management system NHSTDB, technical routes and query language design are dicussed in detail. Finally, a practical application example, demonstrating the use NHSTDB, confirms it is easy and efficiently to use the prototype system.