16.10 - CompressGlobalTempFallbackDBs

16.10 - CompressGlobalTempFallbackDBs - Teradata Database

Teradata Database Utilities

Product

Teradata Database

Release Number

16.10

Published

June 2017

Language

English (United States)

Last Update

2018-04-26

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Purpose

Specifies conditions under which Global Temporary Table data blocks (DBs) in fallback subtables 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.

Field Group

Compression

Valid Settings

Setting	Description
ALWAYS	The DBs of a new table will be compressed regardless of Query Band options specified at load time.
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, 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.