Transaction time

In temporal databases, transaction time (TT), like for example the load datetime,[1] is the time during which a fact stored in the database is considered to be true.

In a database table, the transaction time is often represented as an interval allowing the system to "remove" entries by using two table-columns start_tt and end_tt. The time interval is closed [ at its lower bound and open ) at its upper bound.[2]

When the ending transaction time is unknown, it may be considered as until_changed. Academic researchers and some relational database management systems (RDBMS) have represented until_changed with the largest timestamp supported or the keyword forever. This convention is a technical workaround, and not technically precise.

History

The term transaction time was coined by Richard T. Snodgrass and his doctoral student Ilsoo Ahn (1986).[3]

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).

See also

References
  1. "Transactional Links - AutomateDV". automate-dv.readthedocs.io. Retrieved 2024-02-10.
  2. Kedar, S. V. (2013). Database management systems. Pune, India: Technical Publications.
  3. Snodgrass; Ilsoo Ahn (1986). "Temporal Databases" (PDF). Computer. 19 (9): 35. doi:10.1109/MC.1986.1663327.
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