Specifies the minimum percentage by which the data block (DB) size must be reduced by compression. If compression will not reduce the DB by at least this amount, the DB will not be compressed, because the overhead of having to compress and uncompress the blocks during DML operations is not worth the minimal space savings that might be achieved.
Field Group
Compression
Valid Range
0 through 99 percent
Default
20 percent
Changes Take Effect
After the DBS Control Record has been written.
Usage Notes
BLC enables data compression at the data block (DB) level of the Teradata 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.
Compression is also subject to the criteria specified by the MinDBSectsToCompress DBS Control setting. DBs not meeting these minimum criteria will not be compressed, even if they are larger than the size specified by MinPercentCompReduction.
Related Information
| For more information on... | See... |
|---|---|
| COMPRESS and UNCOMPRESS commands | Ferret Utility (ferret). |