Modeling temporal validity using Oracle Database’s embedded PERIOD

The original concept of the PERIOD data type was specified in the temporal paradigm definition, but it was not, however, completely accepted. The principle was based on providing an extra data type covering the duration, internally modeled by the beginning and end points of the state validity. It was based on direct mapping and comparison; thus, the positional relationships were assumed to be widespread. Thanks to that, sorting the states over the evolution was easy, and there was an emphasis on the consistency of the duration and the definition – the beginning point was placed before the end point. It was primarily designed for validity management, but any time frame could be used generally. Since the standardization process did not approve the concept of the PERIOD data type, many research and development prospects were either refused or at least not further developed. As a result, individual developers...