Purpose
Specifies the temperature at and below which data blocks are automatically compressed if temperature-based block-level compression (TBBLC) is enabled.
Field Group
Compression
Valid Settings
| Setting | Description |
|---|---|
| COLD | Only COLD data is compressed by TBBLC. By default, cold data is the least frequently accessed 20% of data. |
| WARM | WARM and COLD data is compressed by TBBLC. |
| HOT | All data is compressed by TBBLC. |
| n | A floating point number greater than zero and less than or equal to 100 that represents the coldest n percent of table data that is compressed by TBBLC. |
Default
COLD
Changes Take Effect
After the DBS Control Record has been written.
Usage Notes
Tables using TBBLC are those having the BLOCKCOMPRESSION table attribute set to AUTOTEMP.
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 | Database Design |
| BLOCKCOMPRESSION table attribute | SQL Data Definition Language - Syntax and Examples |
| Enabling TBBLC | EnableTempBLC |
| Ferret COMPRESS, UNCOMPRESS, and FORCE commands | Ferret Utility (ferret) |
| Query bands for compression | SQL Data Definition Language - Syntax and Examples |
| Storage group of DBS Control fields | Storage Group |