Impala lists all supported timezones in https://github.com/cloudera/Impala/blob/master/be/src/exprs/timezone_db.cc
As of this ticket's creation, that list has ~380 entries. MySQL, for example, supports about 570 timezones. We should expand the set of timezones to be comparable with other databases.
(Is it just a case of editing TIMEZONE_DATABASE_STR?)
Customer request to include this in 5.4.2