What is temporal data?
In a table with temporal support, the header represents a predicate with at least one time parameter that represents when the rest of the predicate is valid; the complete predicate is therefore a timestamped predicate. Rows represent timestamped propositions, and the row's valid time period is expressed with one of two attributes: since (for semi temporal data) or during (for fully temporal data); the latter attribute is usually represented with two values, from and to. The following table shows the original and two additional timestamped versions of an exemplarySuppliers table:
Original Suppliers table and two tables with temporal support
From the original table header, you can read a predicate saying that a supplier with identification supplierid, named companyname, with a contact contactname, and so on is currently our supplier, or is currently under contract. You pretend that this supplier is the supplier forever. The Suppliers_Since table header has this predicate...
