> On Mar 17, 2015, at 9:30 AM, Paul Jungwirth <pj@xxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > So next question: how do I get the "active" time per hour from this? > > I think you just SUM() over the intersection between each hourly window and each event, right? This might be easiest using tsrange, something like this: Sounds reasonable. I've never worked with range values before, but it does seem appropriate here. > > SUM(extract(minutes from (tsrange(start_time, end_time) && tsrange(h, h + interval '1 hour'))::interval)) > > I think you'll have to implement ::interval yourself though, e.g. here: > > http://dba.stackexchange.com/questions/52153/postgresql-9-2-number-of-days-in-a-tstzrange Gotcha > > Also as mentioned you'll have to convert h from an integer [0,23] to a timestamp, but that seems pretty easy. Assuming start_time and end_time are UTC that's just adding that many hours to UTC midnight of the same day. > > Some weird edge cases to be careful about: activities that cross midnight. Activities that last more than one full day, e.g. start 3/15 and end 3/17. Right. And I will run into some of those (at least the crossing midnight), so I'll keep an eye out. ----------------------------------------------- Israel Brewster Systems Analyst II Ravn Alaska 5245 Airport Industrial Rd Fairbanks, AK 99709 (907) 450-7293 ----------------------------------------------- > > Paul > > > -- > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
