You can override the autocompression default by specifying the NO AUTO COMPRESS option.
If you specify NO AUTO COMPRESS for a column partition, or if the column partition has ROW format, Vantage applies any compression techniques (null compression, multivalue compression, or algorithmic compression) that you specify to every container or subrow of the column partition. For column partitions with COLUMN format, Vantage applies row header compression, which is applied to column partitions that have COLUMN format. To disable row header compression, specify ROW format when you create a column-partitioned table or join index.
There is overhead in determining whether to compress a physical row and if so, what compression techniques to use. If Vantage determines that there is no appropriate technique to compress the physical rows of the column partition, or if you determine that the compression techniques used do not effectively compress the column partition, you can eliminate this overhead by specifying the NO AUTO COMPRESS option for the column partition.