17.10 - Dropping System Versioning and System-Time - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - ANSI Temporal Table Support

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1186-171K
Language
English (United States)

System-versioned system-time tables are typically used for regulatory and compliance purposes, and for keeping a table-resident history of database operations on the table data. Consequently, most types of ALTER TABLE changes to these tables are not allowed. However, ALTER TABLE can be used to remove system versioning. After system versioning has been removed from a temporal table, the table becomes a regular nontemporal table, and all normal ALTER TABLE operations are permitted.

Use the following ALTER TABLE syntax to remove system versioning from a system-time table:

ALTER TABLE  your_system_time_table  DROP SYSTEM VERSIONING;

Where your_system_time_table is the name of a system-versioned system-time table.

Dropping the SYSTEM VERSIONING from a system-time table deletes all closed rows from the table, and makes the table a nontemporal table.

To drop the system-time columns, including the derived period column and its component beginning and ending bound TIMESTAMP columns, use the following ALTER TABLE syntax:

ALTER TABLE  your_system_time_table  DROP PERIOD FOR SYSTEM_TIME;

Where, again, your_system_time_table is the name of a system-versioned system-time table.

Dropping the system-time derived period column will automatically drop the two component columns.

You must drop the SYSTEM VERSIONING from a system-time table before you can drop the SYSTEM_TIME derived period column and component columns.