A temporal database contains time-referenced, or timestamped, facts. A time reference in such a database is absolute if its value is independent of the context, including the current time, now.
An example is “Mary’s salary was raised on March 30, 2007.” The fact here is that Mary’s salary was raised. The absolute time reference is March 30, 2007, which is a time instant at the granularity of day.
Another example is “Mary’s monthly salary was $15,000 from January 1, 2006 to November 30, 2007.” In this example, the absolute time reference is the time period [January 1, 2006–November 30, 2007].
Absolute time can be contrasted with relative time.
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