15.10 - Considerations - Teradata Database

Teradata Database Teradata Virtual Storage

Teradata Database

Temperature-based data migration is available only to sites licensed to use Teradata VS. To license and enable Teradata VS, contact your Teradata sales representative.

Note: Teradata Database temperature-based block-level data compression (TBBLC) does not require a Teradata VS license. For more information about TBBLC, see Database Design and Utilities.

When data is loaded into a new table, Teradata Database does not yet know how frequently the data will be accessed, so the data is initially assigned a temperature specified by the appropriate Storage setting in DBS Control. Typically, you can allow the system to set the temperature according to this setting.

Over time, Teradata VS monitors data access patterns, assigns table data a temperature based on those access patterns, and moves data between faster and slower storage to place the hotter data on faster-accessed physical storage.

For tables with very specific data access requirements, you can use the TVSTemperature query band (at load time) or the Ferret FORCE command (after a table has been created) to lessen the time required to move the data into the proper storage grade.

Note: Only use the TVSTemperature query band or the Ferret FORCE command when you know that the standard background migration will not move the data to appropriate storage quickly enough.

Teradata VS monitors frequency of data access and adjusts data temperatures dynamically as it monitors frequency of data access. Consequently, temperatures can change from those specified using the TVSTemperature query band or the FORCE command, if the measured frequency of actual data access differs from the temperature that is initially set.