Change the owner of all relations within a PostgreSQL database

alter-owner.sql

SELECT exec('ALTER TABLE ' || quote_ident(s.nspname) || '.' || quote_ident(s.relname) || ' OWNER TO $NEWUSER')
FROM (SELECT nspname, relname
    FROM pg_class c JOIN pg_namespace n ON (c.relnamespace = n.oid) 
    WHERE nspname NOT LIKE E'pg\\_%' AND 
      nspname <> 'information_schema' AND 
      relkind IN ('r','S','v') ORDER BY relkind = 'S'
  ) s;

exec.sql

CREATE FUNCTION exec(text) returns text language plpgsql volatile
  AS $f$
    BEGIN
      EXECUTE $1;
      RETURN $1;
    END;
$f$;

Borrowed from http://stackoverflow.com/a/6852484/1760540