15.00 - BLOCKCOMPRESSION - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

Teradata Database
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Programming Reference
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English (United States)


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

The following table lists the available options for BLOCKCOMPRESSION.





The compressed state of the data in the join 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.


The definition of whether the join 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).


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


The join 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 join 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.