For historical reasons (or “hysterical raisins” as gps says) that elude me, the BMO database has been in (ughhh) Pacific Time since it was first created. This caused some weirdness on every daylight savings time switch (particularly in the fall when 2:00-3:00 am technically occurs twice), but not enough to justify the work in fixing it (it’s been this way for close to two decades, so that means lots of implicit assumptions in the code).
However, we’re planning to move BMO to AWS at some point, and their standard db solution (RDS) only supports UTC. Thus we finally had the excuse to do the work, and, after a bunch of planning, developing, and reviewing, the migration happened yesterday without issues. I am unreasonably excited by this and proud to have witnessed the correction of this egregious violation of standard db principles 18 years after BMO was originally deployed.
Thanks to the BMO team and the DBAs!