Prior to ANSI/ISO developing a standard for temporal tables, Teradata developed proprietary technology and syntax for a similar, but more sophisticated temporal paradigm.
Teradata “valid-time” tables qualify as ANSI “application-time” temporal tables, if they are defined using a valid-time derived period column and have no temporal constraints. These tables are ANSI compliant without modifications.
Teradata “transaction-time” tables are analogous to ANSI “system-versioned system-time” temporal tables, but must be converted to system-versioned system-time tables in order to be used with ANSI-compliant temporal SQL. For sites that have implemented transaction-time tables, this appendix provides three methods to convert transaction-time tables to system-time tables. Teradata recommends contacting your Teradata representative for help with this process.
Although Teradata’s original temporal SQL that is used to qualify temporal queries and modifications does operate on Teradata’s ANSI temporal tables, it is not ANSI-compliant SQL.
Note: In order to use ANSI temporal tables on systems that used temporal tables prior to Teradata Database 15.0, the session temporal qualifier must be set to ANSIQUALIFIER. This is normally set appropriately by Teradata personnel. ANSIQUALIFIER changes the SQL behavior with respect to default temporal qualifiers such that unqualified queries and modifications of valid-time tables act as nonsequenced.
You can check the session temporal qualifier setting by looking at the Temporal Qualifier field of the output of the HELP SESSION statement. For more information on HELP SESSION, see SQL Data Definition Language.
For more information on session temporal qualifiers, see SET SESSION in Temporal Table Support.