From http://www.postgresql.org/devel-corner/docs/admin/charset.htm
Once you have chosen a set of localization rules this way you must keep them fixed for any particular database
cluster.That means that the locales that were active when you ran initdb must be kept the same when you start the
postmaster.
Is that still true? I seem to remember something about the postmaster using
whatever initdb set..
Cheers,
Patrick