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