1 hour difference in timestamp/ timestampadd in vertica - Vertica

Question

Why there is a difference of 1 hour in timestamp in vertica . Is it because of Daylight savings? How to avoid that?

Timezone

dbadmin=> show timezone;
   name   |     setting
----------+-----------------
 timezone | America/Toronto

April month shows correct

dbadmin=> select '2022-04-10 09:30:00+0530'::TIMESTAMPTZ;
        ?column?
------------------------
 2022-04-10 00:00:00-04

March month shows 1 hour lag##

dbadmin=> select '2022-03-10 09:30:00+0530'::TIMESTAMPTZ;
        ?column?
------------------------
 2022-03-09 23:00:00-05

I want to go back 30 days from April to March but instead of 2022-03-11 00:00:00-04, I am getting one hour difference '2022-03-10 23:00:00-05', while the same things work well in April-May

April to March

dbadmin=> select TIMESTAMPADD('DAY', -1*30, '2022-04-10 00:00:00-04');
      timestampadd
------------------------
 2022-03-10 23:00:00-05

May to April

dbadmin=>  select TIMESTAMPADD('DAY', -1*30, '2022-05-10 00:00:00-04');
      timestampadd
------------------------
 2022-04-10 00:00:00-04

Answer 1

Thanks for your answer in the comments.

UTC - Greenwich mean time has no daylight saving time. Your local 'America/Toronto' time, however, has it. So you are 4 hours away from UTC in summer, and 5 hours away from UTC in winter.

Works as designed - or "it's not a bug, it's a feature" ....