When you create a column-partitioned table, Vantage compresses the data that you insert into the physical table rows unless you specify the NO AUTO COMPRESS option for the table or for specific column partitions.
Unless you specify NO AUTO COMPRESS, Vantage does the following for column partitions with the COLUMN format:
- Considers the cost of decompressing the data and determines whether autocompression is worthwhile
- Selects a compression method
- Automatically compresses values and decompresses them when you need to retrieve them
Autocompression is most effective for a column partition with a single column and COLUMN format.
Vantage determines whether to apply both autocompression and user-specified multivalue and algorithmic compression to a column, and if the user-specified methods do not help to compress a container, the system only applies autocompression.