15.00 - Other Forms of Compression Used by Teradata Database - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

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

Other Forms of Compression Used by Teradata Database

Teradata Database also supports row compression, block‑level compression, and, for column‑partitioned data only, autocompression.

  • When describing compression of hash and join indexes, compression refers to a logical row compression in which multiple sets of non‑repeating column values are appended to a single set of repeating column values. This allows the system to store the repeating value set only once, while any non‑repeating column values are stored as logical segmental extensions of the base repeating set.
  • When describing the compression of data blocks, compression refers to block‑level compression, or BLC, a lossless physical compression method that can be specified in a CREATE TABLE request.
  • Note: Block‑level compression can be applied to row‑level security constraint columns.

    See Utilities: Volume 1 (A-K) and Support Utilities for information about BLC and the conditions under which Teradata Database applies it to various types of tables.

  • When describing system‑selected autocompression of containers in column‑partitioned tables, compression refers to several different possible compression mechanisms that Teradata Database can use to compress the column values of a container.
  • While multi-value compression and algorithmic compression cannot be applied to row‑level security constraint columns, Teradata Database can apply block compression to such columns.