Every open source column database I've seen is very poor: text, no decent array oriented ability (give me the prevoius row), slow, json output, etc. When will somebody get it right?
This is simply false. PostgreSQL + cstore_ftw, Presto, Impala, etc. all support "array oriented ability" via window functions.
I mean like give me the preceding row from the current. Very useful for calculating anything from a simple rate of change to a properly doing a temporal database. Arrays as a column type doesn't get you that.
No, but window functions do, unless I'm not understanding what your goal is.