Dealing with Temporal Schema Anomalies in History Databases

Abrtract Current databarer do not proceu temporal information well. Databarer containing hirtorieal information (history databaser) have been proposed to provide more temporal capability by appending new data to relationr in&cad of deetructivaly updating them. Becauee hirtory databuee do not dircard data, they cannot diecard outdated database achemae. Thus, in any propoeal for a practical hiitory databw ryrtem, come method murt be provided for accarring data from outdated, yet hirtorically valid, database echemae. This paper investigates the probleme rerulting from restructuring a hirtory database. It then explorer different technique@ for maintaining multiple rchemae. Finally, it presentr Schema Temporal Logic (STL) ae a meane of retrieving data from multiple hirtorically valid databaee rchemae uring temporal logic.