15.00 - BlockCompression Reserved Storage Management Query Bands - 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 Reserved Storage Management Query Bands

Note: As a general rule, customer‑written applications should not use these query band names. They are reserved for use by Teradata‑written applications and applications written by third party Teradata partners.

The primary and fallback subtables of a table can have independent block-level compression attributes. See “Adding, Modifying, or Dropping Block-Level Compression” on page 62 for more information.

You can use the BlockCompression query band with tables whose effective BLOCKCOMPRESSION attribute is MANUAL. In that case, the query band indicates if the data being loaded into an empty primary or fallback table (or both) should be compressed at the data block level.

The specifications apply to permanent or global temporary table data, but do not apply to Spool data or Permanent Journal data.

The compression method used is zlib. See http://zlib.net for more information.

The valid BlockCompression values apply, as noted, to primary data tables, fallback data tables, and work tables.

BlockCompression indicates if the data being loaded into an empty primary or fallback table (or both) should be compressed at the data block level. See “Adding, Modifying, or Dropping Block-Level Compression” on page 62 for more information.

The compression method used is zlib. See http://zlib.net for more information.

 

               Value

                                                     Description

ALL

Compress all new primary and fallback table data at the data block level.

This option is equivalent to specifying YES.

FALLBACK

Compress new fallback data, but do not compress primary table data.

FALLBACKANDCLOBS

Compress fallback data, fallback CLOBs, and primary CLOBs.

  • NO
  • NONE
  • These options are equivalent and specify not to compress new primary and fallback table data at the data block level.

    ONLYCLOBS

    Compress only new CLOB data.

    WITHOUTCLOBS

    Compress all data except for CLOB data.

    YES

    Compress all new primary and fallback table data at the data block level.

    This option is equivalent to specifying ALL.

    You can also control block-level compression using the FERRET utility and the compression fields of the DBS Control record (see Utilities: Volume 1 (A-K)).

    You can use the BlockCompression query band and the DBS Control flags in the following list, or both to control block-level compression.

  • CompressPermPrimaryDBs
  • CompressPermFallbackDBs
  • CompressPermPrimaryCLOBDBs
  • CompressPermFallbackCLOBDBs
  • CompressGlobalTempPrimaryDBs
  • CompressGlobalTempFallbackDBs
  • CompressGlobalTempPrimaryCLOBDBs
  • CompressGlobalTempFallbackCLOBDBs
  • See Utilities: Volume 1 (A-K) for more information about these DBS Control parameters.

    If you use both, the BlockCompression query band setting overrides the DBS Control setting for any affected subtables unless the DBS Control setting is NEVER.

    The following table summarizes the effects on various data of the BlockCompression query band settings.

     

                 Value

           Primary Table

           Fallback Table

    Primary CLOB Subtable

    Fallback CLOB Subtable

    None

    Default

    Default

    Default

    Default

    ALL

    Compressed

    Compressed

    Compressed

    Compressed

    FALLBACK

    Not compressed

    Compressed

    Not compressed

    Compressed

  • NO
  • NONE
  • Not compressed

    Not compressed

    Not compressed

    Not compressed

    ONLYCLOBS

    Not compressed

    Not compressed

    Compressed

    Compressed

    WITHOUTCLOBS

    Compressed

    Compressed

    Not compressed

    Not compressed

    YES

    Compressed

    Compressed

    Compressed

    Compressed