Td13.10 not only enhanced existing Multi valued compression but also introduced two new methods
3. Algorithmic compression
Users can now write their own compression and decompression
algorithms for characters.
These will have to be implemented in UDF and needs to be tested
thoroughly before implementing it in full scale.
There are some samples functions Teradata has provide and can be
found in SYSLIB.
TransUnicodeToUTF8, TransUTF8ToUnicode, LZCOMP, LZDECOMP, LZCOMP_L,
LZDECOMP_L, CAMSET, DECAMSET, CAMSET_L,DECAMSET_L.
4. Block level compression (applicable to DBA’s, Capacity
planners)
BLC is applied at data blocks and allows row data to be stored
in datablocks* in a
new compressed format.
To enable BLC on tables, new command "COMPRESS" is
available in FERRET utility. After BLC is enabled on table, all tows added to
table are compressed automatically. Similarly "UNCOMPRESS" command
can be used to uncompress packed Data.
BLC is one of most straight forward methods where one doesn’t
have to worry about type of data across various columns in table. Row header
and internal Teradata structures are also compressed using BLC.
BLC plays major role in saving lot of I/O and Space but at same
time it can have some performance implications as more CPU can be utilized to
compress and uncompress data dynamically.
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