Re: UUID v7

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