Here's a query that should reveal 1/2 the problems...??
select t.tz_id, t.utc_start, t.utc_end, u.utc_start, u.utc_end
from timezone_rules t, timezone_rules u
where t.tz_id=u.tz_id
and t.utc_start < u.utc_start
and t.isdst_p = 'f' and u.isdst_p = 't'
and u.utc_start < t.utc_end and
not exists (select z.tz_id
from timezone_rules z
where z.utc_start between t.utc_end and u.utc_start)
order by tz_id, t.utc_start, u.utc_start
limit 20;
tz_id | utc_start | utc_end | utc_start | utc_end
-------+------------------------+------------------------+------------------------+------------------------
15 | 2001-10-28 01:00:00-08 | 2002-03-31 12:59:59-08 | 2002-03-31 01:00:00-08 | 2002-10-27 12:59:59-08
15 | 2002-10-27 01:00:00-08 | 2003-03-30 12:59:59-08 | 2003-03-30 01:00:00-08 | 2003-10-26 12:59:59-08
15 | 2003-10-26 01:00:00-08 | 2004-03-28 12:59:59-08 | 2004-03-28 01:00:00-08 | 2004-10-31 12:59:59-08
15 | 2004-10-31 01:00:00-08 | 2005-03-27 12:59:59-08 | 2005-03-27 01:00:00-08 | 2005-10-30 12:59:59-08
15 | 2005-10-30 01:00:00-08 | 2006-03-26 12:59:59-08 | 2006-03-26 01:00:00-08 | 2006-10-29 12:59:59-08
15 | 2006-10-29 01:00:00-08 | 2007-03-25 12:59:59-08 | 2007-03-25 01:00:00-08 | 2007-10-28 12:59:59-08
52 | 2002-04-07 12:00:00-07 | 2002-09-01 12:59:59-07 | 2002-09-01 01:00:00-07 | 2003-04-05 11:59:59-08
52 | 2003-04-06 12:00:00-07 | 2003-09-07 12:59:59-07 | 2003-09-07 01:00:00-07 | 2004-04-03 11:59:59-08
52 | 2004-04-04 12:00:00-07 | 2004-09-05 12:59:59-07 | 2004-09-05 01:00:00-07 | 2005-04-02 11:59:59-08
52 | 2005-04-03 12:00:00-07 | 2005-09-04 12:59:59-07 | 2005-09-04 01:00:00-07 | 2006-04-01 11:59:59-08
52 | 2006-04-02 12:00:00-07 | 2006-09-03 12:59:59-07 | 2006-09-03 01:00:00-07 | 2007-03-31 11:59:59-08
52 | 2007-04-01 12:00:00-07 | 2007-09-02 12:59:59-07 | 2007-09-02 01:00:00-07 | 2008-04-05 11:59:59-08
91 | 2001-10-28 01:00:00-07 | 2002-03-31 12:59:59-08 | 2002-03-31 01:00:00-08 | 2002-10-27 12:59:59-08
91 | 2002-10-27 01:00:00-07 | 2003-03-30 12:59:59-08 | 2003-03-30 01:00:00-08 | 2003-10-26 12:59:59-08
91 | 2003-10-26 01:00:00-07 | 2004-03-28 12:59:59-08 | 2004-03-28 01:00:00-08 | 2004-10-31 12:59:59-08
91 | 2004-10-31 01:00:00-07 | 2005-03-27 12:59:59-08 | 2005-03-27 01:00:00-08 | 2005-10-30 12:59:59-08
91 | 2005-10-30 01:00:00-07 | 2006-03-26 12:59:59-08 | 2006-03-26 01:00:00-08 | 2006-10-29 12:59:59-08
91 | 2006-10-29 01:00:00-07 | 2007-03-25 12:59:59-08 | 2007-03-25 01:00:00-08 | 2007-10-28 12:59:59-08
154 | 2001-10-28 01:00:00-08 | 2002-03-31 12:59:59-08 | 2002-03-31 01:00:00-08 | 2002-10-27 12:59:59-08
154 | 2002-10-27 01:00:00-08 | 2003-03-30 12:59:59-08 | 2003-03-30 01:00:00-08 | 2003-10-26 12:59:59-08
(20 rows)
