Querying Temporal Databases with Multiple Views

Abstract

A prominent feature of temporal information is its richness in semantics associated with its temporal domain. When querying a temporal database, a user naturally assumes some “usual” semantics on stored temporal data. For instance, she expects that her bank account balance persists, i.e., the balance stays the same unless a transaction—deposit, withdrawal, or accrual of interest—is performed. Therefore, if she wishes to find the balance at a particular time and no balance amount is stored for that time, she looks for the balance of the last transaction that was performed before the time in question. Semantic assumptions may also involve different time granularities. For example, when the user asks for the account holder of a certain account in a particular month and account holders are stored in terms of days, she assumes that the answer is someone who is the account holder of that account on all the days within that month.

Do nothing secretly; for Time sees and hears all things, and discloses all.

Sophocles. 496–406 B. C.