Literature Review on Temporal, Spatial, and Spatiotermpoal Data Models

Conventional database systems are capable of storing only the current perception of reality and the current relationship among objects. Such databases enforce currency of data by excluding old data values when newer ones become available. After such currency updates, the old values are lost from the logical level and only the current state remains available. On the other hand, temporal database systems are capable of storing multiple versions of data, thereby allowing users the facility of examining complete object histories [1]. Chomicki defined a temporal database as a repository of temporal information and a temporal query language as any query language for temporal databases in [2]. Jensen in [3] argued that most applications of database technology are temporal in nature and listed applicable examples such as financial applications, record-keeping applications, scheduling applications, and scientific applications. He also pointed out that temporal database management is a vibrant field of research and an active community of several hundred researchers had produced some 2000 papers1. Temporal databases can be classified into two groups based on schemes of timestampping. The first one is a tuple level timestampping and the second one is an attribute level timestampping. Temporal databases also can be classified into three categories based on the feature of timestamps– point-based, interval-based, and temporal element-based. Therefore, there are six different combinations possible. The parametric database is the attribute timestampping and temporal elements are used as timestamp. In this chapter, we will discuss temporal data models and their temporal query languages. There exist many temporal query languages and examples include TQuel, TSQL2, SQLT , IXSQL, SQL/TP, TOLAP, TOSQL, HSQL, ChronoSQL, SQL/Temporal, and so on. Since ParaSQL is an extended SQL and we need to compare it with other temporal query languages, we only select four temporal query languages–SQL/TP, IXSQL, SQLT , and TSQL2. All queries used in this chapter are from literature describing each query language.