Purpose
Specifies the maximum threshold number of outstanding I/O operations that can exist on a node above which the background temperature-based block-level compression (TBBLC) task pauses for a short period before running again. If the system remains busy, the process waits according to the interval defined by TempBLCInterval.
This field is effective only when TBBLC is enabled.
Field Group
Compression
Valid Range
1 through 1,000
Default
1
Changes Take Effect
After the DBS Control Record has been written.
Usage Notes
This field limits the impact of TBBLC on foreground workloads.
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 |