From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: jian he <jian.universality@gmail.com>
Cc: Francisco Olarte <folarte@peoplecall.com>
Cc: Michael Bondarenko <work.michael.2956@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org, dgrowleyml@gmail.com, Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Subject: Re: BUG #18348: Inconsistency with EXTRACT([field] from INTERVAL);
Date: Fri, 16 Aug 2024 11:26:58 -0400
Message-ID: <Zr9vwnzROmfi_MI4@momjian.us> (raw)
In-Reply-To: <Zr69ZnXWlS_2_bvI@momjian.us>
References: <3749306.1708222748@sss.pgh.pa.us>
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<222870.1708458150@sss.pgh.pa.us>
<270582.1708462564@sss.pgh.pa.us>
<CACJufxFOjGpAQJ5EJ0=a1geERgdHW77SEdRyK8A_qwB3CVdwhQ@mail.gmail.com>
<166456.1715117228@sss.pgh.pa.us>
<CACJufxGFuZsj+31a204fFpxv_RCHA-u1h6WEBZ6qpjBVoio5dQ@mail.gmail.com>
<476283.1715177448@sss.pgh.pa.us>
<1079670.1720458208@sss.pgh.pa.us>
<Zr69ZnXWlS_2_bvI@momjian.us>
On Thu, Aug 15, 2024 at 10:45:58PM -0400, Bruce Momjian wrote:
> > We could fix that by examining the sign of the lower-order fields
> > when month is zero, as in the v3 patch attached. However, I'm not
> > at all sure this is really better than v2. Notably, it makes the
> > documentation's statement that the result is "the month field
> > divided by 3 plus 1" even more incomplete. I still don't really
> > want to go into details about the behavior for negative intervals.
> > OTOH if we did do that, I'd rather write a blanket statement
> > about the result being the negative of the result for a positive
> > interval.
> >
> > Thoughts?
>
> I tested master, patch version 2 and patch version 3 with some sample
> extract() queires, attached. I like patch version 2. Patch version 3
> bothers me because "-600 days" is ignored if months is non-zero, and
> used for its sign for zero month values, which seems odd to me; better
> to ignore it.
I think there are two more issues. In patch version 3, when months is
zero and you check days, you should also check seconds if days is zero.
I think the other issue is that zero months is a valid Q1 value, since
months 0-2 are Q1; from master:
SELECT extract(quarter FROM interval '0 months');
extract
---------
1
SELECT extract(quarter FROM interval '2 months');
extract
---------
1
SELECT extract(quarter FROM interval '3 months');
extract
---------
2
so the idea that we should adjust the sign for zero months quarter
extract doesn't seem logical to me.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com
Only you can decide what is important to you.
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To: pgsql-bugs@postgresql.org
Cc: bruce@momjian.us, tgl@sss.pgh.pa.us, jian.universality@gmail.com, folarte@peoplecall.com, work.michael.2956@gmail.com, peter.eisentraut@enterprisedb.com
Subject: Re: BUG #18348: Inconsistency with EXTRACT([field] from INTERVAL);
In-Reply-To: <Zr9vwnzROmfi_MI4@momjian.us>
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