temporal database A temporal database stores data relating to time instances. It offers temporal data types and stores information relating to past, present and future time. Temporal databases could be uni-temporal, bi-temporal or tri-temporal. More specifically th ...

s, transaction time (TT) is the time during which a fact stored in the database is considered to be true. As of December 2011, ISO/IEC 9075, Database Language SQL:2011 Part 2: SQL/Foundation included clauses in table definitions to define "system-versioned tables" (that is, transaction-time tables). In a database table transaction interval is often represented as an interval allowing the system to "remove" entries by using two table-columns ''StartTT'' and ''EndTT''. The time interval is closed at its

lower bound In mathematics, particularly in order theory, an upper bound or majorant of a subset of some preordered set is an element of that is greater than or equal to every element of . Dually, a lower bound or minorant of is defined to be an ele ...

and open at its

upper bound In mathematics, particularly in order theory, an upper bound or majorant of a subset of some preordered set is an element of that is greater than or equal to every element of . Dually, a lower bound or minorant of is defined to be an elem ...

. When the ending transaction time is unknown, it may be considered as "Until Changed". Academic researchers and some RDBMS have represented "Until Changed" with the largest timestamp supported or the keyword "forever". This convention is not technically precise. The term was coined by

Richard T. Snodgrass Richard Thomas Snodgrass (born April 19, 1955) is an American computer scientist and writer and is professor emeritus at the University of Arizona. He is best known for his work on temporal databases, query language design, query optimization a ...

and his doctoral student Ilsoo Ahn.

References

Database management systems Transaction processing {{Compu-prog-stub

See also

References