Session Temporal Qualifiers | Temporal Table Support | Teradata Vantage - 17.05 - Session Temporal Qualifiers - Teradata Database

Teradata Vantage™ - Temporal Table Support

prodname
Advanced SQL Engine
Teradata Database
vrm_release
17.00
17.05
created_date
June 2020
category
Programming Reference
featnum
B035-1182-170K

The SET SESSION statement lets you set session temporal qualifiers in the valid-time dimension, transaction-time dimension, or both dimensions. When a DML or SELECT statement refers to a temporal table but omits a temporal qualifier, the system uses the value of the session temporal qualifier.

A session temporal qualifier of CURRENT VALIDTIME AND CURRENT TRANSACTIONTIME allows applications written prior to the temporal capability to continue functioning without modifications in a non-temporal way on tables that may have been converted to temporal tables.

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 session temporal qualifiers, see SET SESSION (Session Temporal Qualifiers). For more information on HELP SESSION, see Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144.

Best practice is to always use explicit temporal qualifiers on SELECT and DML statements that operate on temporal tables, rather than relying on the default temporal session qualifiers.