Each field in the Storage group specifies the initial temperature that will be assigned to data loaded or inserted into empty subtables of a particular type. The temperature represents the expected frequency of access to that data, and can determine whether the data is compressed, and where the data is stored.
The individual Storage setting names and defaults are listed below. These fields are relevant and visible only when temperature-based block level compression (TBBLC) is enabled, or on systems that have licensed Teradata Virtual Storage (VS).
|Storage Field||Default Temperature|
|GLOBAL TEMP Fallback Temperature||WARM|
|GLOBAL TEMP Fallback CLOB Temperature||WARM|
|GLOBAL TEMP Primary Temperature||WARM|
|GLOBAL TEMP Primary CLOB Temperature||WARM|
|PERMANENT JOURNAL Temperature||HOT|
|PERM Fallback Temperature||WARM|
|PERM Fallback CLOB Temperature||WARM|
|PERM Primary Temperature
The Parallel Upgrade Tool (PUT) sets the default for PERM primary data based on the system configuration. For some configurations the default is HOT.
|PERM Primary CLOB Temperature||WARM|
|All Other Temperature
Controls initial data temperature set for data loaded into empty subtables that are not specifically controlled by other Storage group fields.
|HOT||Data is expected to be accessed frequently.|
|WARM||Data is expected to be accessed moderately frequently.|
|COLD||Data is expected to be accessed infrequently.|
|DEFAULT||Uses the default temperature for this type of data. Resets the field to the factory default value for the specified table or data type.|
Changes Take Effect
After the DBS Control record has been written.
The Storage field settings are honored when data is loaded into empty tables by any of the following techniques:
- INSERT/INSERT ... SELECT statement
- CREATE TABLE AS ... WITH DATA statement
- CREATE JI statement
- Load utilities TPump, FastLoad, MultiLoad, Teradata Parallel Transporter
- Teradata Archive/Recovery (ARC) utility
- Table Rebuild utility
Because data temperature is assigned at the cylinder level, after initial assignment, data in different partitions of a partitioned table can have different temperatures.
For systems licensed to use Teradata VS, data can be automatically moved (migrated) to faster or slower grades of storage as data temperatures change due to changing data access patterns.