The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/12/functions-datetime.html
Description:
In the documentation of the date_trunc function (9.9.2), the first argument
(field) cannot be 'week' if the second argument (source) is an interval:
csauer=# SELECT DATE_TRUNC('week', INTERVAL '7 days');
ERROR: interval units "week" not supported because months usually have
fractional weeks
csauer=# SELECT DATE_TRUNC('week', INTERVAL '1 week');
ERROR: interval units "week" not supported because months usually have
fractional weeks
The documentation should state that explicitly.
I also think the error message could be improved, because in the cases above
there are no months involved and the result should be 1.
