15.00 - CompressGlobalTempFallbackCLOBDBs - Teradata Database

Teradata Database Utilities

Product
Teradata Database
Release Number
15.00
Content Type
Configuration
Publication ID
B035-1102-015K
Language
English (United States)
Last Update
2018-09-25

CompressGlobalTempFallbackCLOBDBs

Purpose  

Specifies conditions under which Global Temporary Table CLOB data blocks (DBs) in fallback tables will be compressed by default.

Note: Compression is subject to the “BlockLevelCompression” setting, and to the criteria specified by the “MinPercentCompReduction” and “MinDBSectsToCompress” DBS Control settings. DBs not meeting these minimum criteria will not be compressed.

Field Group

Compression

Valid Settings

 

Setting

Description

ONLYIFQBYES

The DBs of a new table will not be compressed unless a Query Band used at load time specified to compress them.

UNLESSQBNO

The DBs of a new table will be compressed unless a Query Band used at load time specified not to compress them.

NEVER

The DBs of a new table will not be compressed regardless of any Query Band used at load time. The Ferret utility COMPRESS command will have no effect.

Default

NEVER

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 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, only primary, fallback, and CLOB subtables, and join and hash indexes are eligible for BLC. Secondary indexes on primary rows are never compressed, but fallback copies of secondary indexes can be compressed to save space.

Related Topics

 

For more information on...

See...

BlockLevelCompression setting

“BlockLevelCompression” on page 241.

COMPRESS and UNCOMPRESS commands

Chapter 13: “Ferret Utility (ferret).”

BLOCKCOMPRESSION query band

SQL Data Definition Language.