Hi, > No. > > Timestamp and TimestampTz are absolutely the same thing. The only > difference is how they are shown to the user. TimestampTz uses session > context in order to be displayed in the TZ chosen by the user. Thus > typically it is somewhat more confusing to the users and thus I asked > whether there was a good reason to choose TimestampTz over Timestamp. > > > Theoretically, you're right. But look at this example: > > SET timezone TO 'Europe/Warsaw'; > SELECT extract(epoch from '2024-01-18 9:27:30'::timestamp), extract(epoch > from '2024-01-18 9:27:30'::timestamptz); > > date_part | date_part > ------------+------------ > 1705570050 | 1705566450 > (1 row) > > In my opinion, timestamptz gives greater guarantees that the time internally > is in UTC and the user gets the time in his/her time zone.
I believe you didn't notice, but this example just proves my point. In this case you have two timestamps that are different _internally_, but the way they are _shown_ is the same because the first one is in UTC and the second one in your local session timezone, Europe/Warsaw. extract(epoch ...) extract UNIX epoch, i.e. relies on the _internal_ representation. This is why you got different results. This demonstrates that TimestampTz is a permanent source of confusion for the users and the reason why personally I would prefer if UUIDv7 always used Timestamp (no Tz). TimestampTz can be converted to TimestampTz by users who need them and have experience using them. -- Best regards, Aleksander Alekseev
