Tables can be block compressed, depending on the DBS Control compression settings or whether the tables have been compressed or decompressed using the Ferret utility. For information about the DBS Control and Ferret utilities and how the block compression settings interact with other DBS Control file system settings, see Teradata Vantage™ - Database Utilities , B035-1102 .
Limits on data block sizes apply to the noncompressed size of a table. Block compression does not raise any of these limits, nor does it enable more data to be stored in a single data block than can be stored in an noncompressed data block of the same size.
Whether volatile table and global temporary tables are compressed or not depends on whether the Optimizer caches the relation in the request cache. See Teradata Vantage™ - SQL Request and Transaction Processing, B035-1142. If a relation is cached, it is not compressed. If the relation is not cached, it is compressed.