Specifies whether Permanent Journal (PJ) data blocks (DBs) will be compressed by default.
Compression is subject to the BlockLevelCompression field setting, and to the criteria specified by the MinPercentCompReduction and MinDBSectsToCompress DBS Control fields. DBs not meeting these minimum criteria will not be compressed.
|ALWAYS||The DBs of a new PJ table will be compressed.|
|NEVER||The DBs of a new PJ table will not be compressed. The Ferret utility COMPRESS command will have no effect.|
Changes Take Effect
After the DBS Control Record has been written.
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.
BLC can be enabled or disabled system-wide, or for various categories of tables. For Permanent data, these include subtables for primary, fallback, eligible LOB data, and join and hash indexes. Secondary indexes on primary rows are never compressed, but fallback copies of secondary indexes can be compressed to save space.
|For more information on...||See...|
|COMPRESS and UNCOMPRESS commands||Ferret Utility (ferret).|
|Permanent Journals||Database Design.|