Sun, 25 Oct 2009

DST Ends

Here in the U.S. Daylight Savings Time (DST) ends next week. I'm on call, so I'm intimately familiar with this event. Hopefully, the systems I am responsible for will weather the change without incident. We spoke with relatives in Spain today which has already gone through the change -- today, to be exact. We had forgotten about that and got up an hour earlier than we needed to for the call. Oh well, live and learn.

Our systems deal in local time and, thus, we have to worry about the long day caused by the extra hour at 3:00 AM. Because we deal with hourly markets, we need to store the 25th hour of information and deal with it in all our systems. It can be quite a mess if we get it wrong and our teams have been testing for some time. I think we're ready and we are minimizing the number of changes this week to assure that everything goes smoothly.

Time -- 24 hours, 60 minutes, 60 seconds -- and dates -- Days, weeks, months -- has always been a bit of a bugger for computer systems which must deal with it. And daylight savings time only adds to the interest. For example, if you deal in data which must be stored and tracked, you have to figure out a way to deal with the fact that you have one day each year with 23 hours -- the short day -- and one day with 25 hours -- the long day. To make things even more interesting, if you store historical data, you must compensate for the fact that this day was different a number of years ago! And, of course, here in the States, there are a number of places which don't go on daylights savings time. Don't get me started about Arizona!

posted 18:18 [/Technology] permanent link