Specifies conditions under which data blocks (DBs) for spool and volatile tables will be compressed by default.
|ALWAYS||The DBs of a new Spool table will be compressed.|
|NEVER||The DBs of a new Spool table will not be compressed. The Ferret utility COMPRESS command will have no effect.|
|IFNOTCACHED||The DBs of a new table will be compressed if they are not being cached.|
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.
Spool includes Persistent Spool used for the Redrive feature.