Re: Fix overflow in justify_interval related functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Nathan Bossart <nathandbossart(at)gmail(dot)com>
Cc: Joseph Koshakow <koshy44(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Fix overflow in justify_interval related functions
Date: 2022-02-14 18:55:56
Message-ID: 2914902.1644864956@sss.pgh.pa.us
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Nathan Bossart <nathandbossart(at)gmail(dot)com> writes:
> On Sun, Feb 13, 2022 at 01:28:38PM -0500, Joseph Koshakow wrote:
>> +SELECT justify_hours(interval '2147483647 days 24 hrs');
>> +ERROR: interval out of range

> The docs [0] claim that the maximum value for interval is 178 million
> years, but this test case is only ~6 million. Should we instead rework the
> logic to avoid overflow for this case?

I think the docs are misleading you on this point. The maximum
value of the months part of an interval is 2^31 months or
about 178Myr, but what we're dealing with here is days, which
likewise caps at 2^31 days. justify_hours is not chartered
to transpose up to months, so it can't avoid that limit.

regards, tom lane

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