15.00 - BLOCKCOMPRESSION - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

prodname
Teradata Database
vrm_release
15.00
category
Programming Reference
featnum
B035-1184-015K

BLOCKCOMPRESSION

Use this option to set the block compression state of a hash index.

The following table lists the available options for BLOCKCOMPRESSION.

 

      Option

                                                             Description

AUTOTEMP

The compressed state of the data in the hash index can be changed by Teradata Database at any time based on its temperature.

You can still issue query band options or Ferret commands, but if the compressed state of the data does not match its temperature, such changes might be undone by the system over time.

DEFAULT

The definition of whether the hash index uses the MANUAL, AUTOTEMP or NEVER compression options is determined by the DBS Control flag DefaultTableMode (see Utilities: Volume 1 (A-K) for details).

MANUAL

The compressed state of the data in the hash index does not change unless you take specific action to do so using Ferret commands.

NEVER

The hash index is not compressed even if the DBS Control block compression settings indicate otherwise.

This means that Teradata Database rejects Ferret commands to manually compress the hash index, but Ferret commands to decompress the index are valid.

See Utilities: Volume 1 (A-K) for information about how to use the Ferret utility.