Re: BUG #18348: Inconsistency with EXTRACT([field] from INTERVAL);

On Sat, 17 Feb 2024 at 01:27, PG Bug reporting form
<noreply@postgresql.org> wrote:
> tpch=# select extract(week from interval '3 weeks');
> ERROR:  interval units "week" not supported
>
> In the documentation it's mentioned that 'week' is an ISO 8601 week, so it
> makes sense why it's not applicable to INTERVAL, which is the same for
> isoyear. However, the field is named week and not isoweek, so I expect it to
> work like the `select extract(year from interval '3 years');` does.
> Moreover, the documentation does not mention that the field cannot be
> extracted from INTERVAL, like it does for isoyear:
> https://www.postgresql.org/docs/current/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT

Maybe that table should specify which type(s) each of the items listed
is applicable to. Seems better than mentioning which types they're not
applicable to.

David