Implementing COMPRESSION in Teradata is the best method for freeing some space in Teradata WareHouse environment. Compression Technique in Teradata has been there for sometime now and with every new release Teradata is working on it to make it more and more useful.
Guidelines for implementing Compression in Teradata are as follows:
a) Compression is valid only for FIXED width columns.
b) The length limit for CHAR columns is 255 characters or less.
c) The columns should not be a part of PRIMARY INDEX.
d) Adding COMPRESS to any column will by default COMPRESS NULL’s.
e) COMPRESS values are CASESPECIFIC , so COMPRESS ‘RAJ’ will not COMPRESS ‘raj’.
f) You can add upto 255 values for any column for COMPRESSION.
IMPROVEMENTS IN TERADATA 13.10
a) Now it includes VARCHAR datatype columns also for COMPRESSION.
b) The limit has been increased from 255 characters to 510 characters.
c) Also includes other datatypes like GRAPHIC, VARGRAPHIC.
To check for other methods for freeing space check : How to free some space in Teradata Database