System Clocks | ANSI Temporal Table Support | Teradata Vantage - System Clocks - Advanced SQL Engine - Teradata Database

ANSI Temporal Table Support
Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Published
July 2021
Language
English (United States)
Last Update
2021-07-27
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B035-1186
lifecycle
previous
Product Category
Teradata Vantage™
Temporal table support depends on all database system nodes running network time protocol (NTP). NTP keeps the system node clocks synchronized within 100 milliseconds. If NTP is unavailable on the system, or is not running on any system node, temporal table support is disabled.
NTP is not required on SMP systems.
To install the teradata-ntp package:
  1. Go to https://support.teradata.com.
  2. Log in.

To configure NTP, see Knowledge Article KAP1A9C72, also available at https://support.teradata.com.

The database can manage the small differences between node clocks due to the minute drift that NTP allows. In the unlikely event that an update is made to an existing row such that the beginning of a time period is after the end time, the transaction is automatically aborted.

Teradata recommends synchronizing the system to an external master time source, such as a Web-based or government sponsored standard time service.

Do not make manual changes to individual node clocks. Circumventing NTP, as by the use of operating system commands to directly change the current time on a node, will compromise temporal table support, and could result in incorrect data or a loss of data.

When new nodes are added to the system, the database administrator must manually set the initial time on those nodes. The time must closely match the time on the other nodes in the system. If a node must be replaced, the initial time set on the replacement must be greater (later) than the time the previous node went down.