Vantage applies user-specified compression for columns within a multicolumn column partition value, but Vantage applies autocompression to a column partition value as a whole.
Vantage may decide not to use one or more of the user-specified compression techniques with autocompression, if other (or no) autocompression techniques provide better compression for a container.
When constructing a container, the system first applies any user-specified compression. When the container reaches an internally defined size limit, Vantage determines what autocompression techniques and user-specified compression can be used to reduce its size. After compressing the container, the system can append additional column partition values using the method of autocompression determined to be optimal and any user-specified techniques until a container size limit is reached, when Vantage constructs a new container.
Alternatively, the system may decide that reusing the compression from the previous container and applying that compression when constructing a new container is more efficient.
If you specify block-level compression (which is not an autocompression technique) for a column-partitioned table or join index, Vantage applies block compression to data blocks independently of autocompression.