I think it is your company who published good results of using compression with PostgreSQL on ZFS. Also column stores contain not just actual column values, e.g

I think it is your company who published good results of using compression with PostgreSQL on ZFS. Also column stores contain not just actual column values, e.g. if you look at cassandra, each SSTable value has key, timestamp, column name, and actual cell value, or the same data layout as 4 columns in row store. Still they strongly recommend to use compression.