Purpose
Determines whether temperature-based block-level compression (TBBLC) is enabled.
Field Group
Compression
Valid Settings
| Setting | Description |
|---|---|
| TRUE | TBBLC is enabled. Tables using AUTOTEMP compression (specified in CREATE TABLE or ALTER TABLE statements) will have infrequently accessed data blocks automatically compressed for storage. In order to use TBBLC, BlockLevelCompression must be set to On.
|
| FALSE | TBBLC is disabled. Data blocks are not compressed based on frequency of access. |
Default
FALSE
Changes Take Effect
After the DBS Control Record has been written.
Usage Notes
When TBBLC is enabled, AutoCylPackColdData should be set to TRUE, and DisableAutoCylPack should be set to FALSE.
If TBBLC is disabled, tables that are set to use automatic temperature-based compression will behave like tables set to use manual compression until TBBLC is enabled again. The system default for whether tables use manual or automatic compression is set with the DefaultTableMode setting.
BLC enables data compression at the data block (DB) level of the Teradata Database file system. Compression reduces the amount of storage required for a given amount of data. The BlockLevelCompression field of DBS Control enables and disables BLC.
Data temperature refers to the frequency of access. Hot data is frequently accessed. Cold data is infrequently accessed. Warm data is accessed moderately frequently. TBBLC automatically compresses colder data to save storage space, and decompresses the data if it becomes hotter. At any time, different portions of a table, such as different partitions, may exist in different states of compression depending on their temperatures.
Related Topics
| For more information on… | See… |
|---|---|
| Block-level compression | Teradata Vantage™ - Database Design, B035-1094. |
| BLOCKCOMPRESSION table attribute | Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144. |
| DefaultTableMode field | DefaultTableMode. |
| Ferret COMPRESS, UNCOMPRESS, and FORCE commands | Ferret Utility (ferret). |
| Query bands for compression | Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144. |
| Storage group of DBS Control fields | Storage Group. |