Re: Problem in age on a dates interval - Mailing list pgsql-sql

From Tom Lane
Subject Re: Problem in age on a dates interval
Date
Msg-id 20678.1089988447@sss.pgh.pa.us
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In response to Re: Problem in age on a dates interval  (Theodore Petrosky <tedpet5@yahoo.com>)
Responses Re: Problem in age on a dates interval
List pgsql-sql
Theodore Petrosky <tedpet5@yahoo.com> writes:
> wow.... at first I thought I had my head around a leap
> year problem so I advanced your query a year....

I think what's going on here is a difference of interpretation about
whether an "M months D days" interval means to add the months first
or the days first.  For instance

2005-02-18 plus 2 months = 2005-04-18, plus 24 days = 2005-05-12

2005-02-18 plus 24 days = 2005-03-14, plus 2 months = 2005-05-14

The timestamp-plus-interval operator is evidently doing addition the
first way, but it looks like age() is calculating the difference in a
way that implicitly corresponds to the second way.

I have some vague recollection that this has come up before, but
I don't recall whether we concluded that age() needs to be changed
or not.  In any case it's not risen to the top of anyone's to-do list,
because I see that age() still acts this way in CVS tip.
        regards, tom lane


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