Vantage software includes standard compression algorithms, in the form of UDFs, which you can use to compress data by table column. You can also create custom compression and decompression algorithms in UDF format.
When column values are unique, algorithmic compression (ALC) may provide better compression results than MVC. When columns have repeated values, you can use ALC and MVC on the same column, but the system does not apply ALC to any value covered by MVC.
ALC functions best on infrequently used data because of the amount of CPU required for decompress/recompress when compressed data is accessed. ALC is considered more difficult to implement than the other compression methods.
You can use algorithmic compression to compress table columns with the following data types:
- ARRAY
- BYTE
- VARBYTE
- BLOB
- CHARACTER
- VARCHAR
- CLOB
- JSON, with the following restrictions
- DATASET, with the following restrictions
- TIME and TIME WITH TIME ZONE
- TIMESTAMP and TIMESTAMP WITH TIME ZONE
- Period types
Topics
Related Information
| Topic | Reference |
|---|---|
| Specifying a UDF in the COMPRESS USING phrase of a CREATE TABLE or ALTER TABLE statement |
|
| System-defined external UDFs for algorithmic compression and decompression | Compression/Decompression Functions |
| How to create the SQL definition for an algorithmic compression UDF | CREATE FUNCTION and REPLACE FUNCTION (External Form) |
| How to specify those scalar UDFs in a table definition | |
| Evaluating algorithmic compression UDFs | Download the Algorithmic Compression Test Package from https://downloads.teradata.com. |