From the PostgreSQL docs
(http://www.postgresql.org/docs/9.4/static/datatype-character.html):
> Tip: There is no performance difference among these three types,
> apart from increased storage space when using the blank-padded type,
> and a few extra CPU cycles to check the length when storing into a
> length-constrained column. While character(n) has performance
> advantages in some other database systems, there is no such advantage
> in PostgreSQL; in fact character(n) is usually the slowest of the
> three because of its additional storage costs. In most situations
> text or character varying should be used instead.
