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
- Valid time
- Decision time
- Using transaction time
References
- v
- t
- e
- Flat
- Hierarchical
- Dimensional
- Network
- Relational
- Entity–relationship
- Graph
- Object-oriented
- Entity–attribute–value
This computer-programming-related article is a stub. You can help Wikipedia by expanding it. |
- v
- t
- e