|TRUE||The system default settings for block-level compression are used to determine whether restored tables are block-level compressed.|
|FALSE||The effective table BLOCKCOMPRESSION value at the time of archiving determines whether restored tables are block-level compressed.|
Changes Take Effect
After the DBS Control Record has been written.
This field does not affect tables with effective BLOCKCOMPRESSION values of ALWAYS or NEVER. This includes tables that were created or altered to have their BLOCKCOMPRESSION option:
- set to ALWAYS or NEVER
- set to DEFAULT, and the DefaultTableMode DBS Control field is set to ALWAYS or NEVER
- unspecified, and the DefaultTableMode DBS Control field is set to ALWAYS or NEVER
This field does not affect subtables for which the effective BLOCKCOMPRESSION is set to ALWAYS or NEVER on the target system to which the data is restored.
For permanent tables and global temporary tables, different subtables hold primary data, fallback data, and LOB data. BLC for these categories of data can be independently controlled using DBS Control Compression fields 14 - 21 (Compress...DBs fields). These subtable settings are effective only when the BLOCKCOMPRESSION setting for the corresponding base table is set to MANUAL, either explicitly, or as a result of being set to DEFAULT (or left unset) while the DefaultTableMode DBS Control field is set to MANUAL.
Block compression that is controlled by the BLOCKCOMPRESSION query band takes precedence over the OverrideARCBLC field 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.
|For More Information on…||See…|
|Block-level compression||Database Design, B035-1094|
|DBS Control fields that determine effective BLOCKCOMPRESSION value for different types of subtable data|
|BLOCKCOMPRESSION table option and BLOCKCOMPRESSION query band||SQL Data Definition Language - Syntax and Examples, B035-1144|