Horton

Re: BRIN minmax multi - incorrect distance for infinite timestamp/date

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

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From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-10-19T12:41:34Z
Lists: pgsql-hackers 
On Thu, Oct 19, 2023 at 4:51 PM Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
>
> On 10/19/23 11:22, Ashutosh Bapat wrote:
> > On Thu, Oct 19, 2023 at 2:31 PM Tomas Vondra
> > <tomas.vondra@enterprisedb.com> wrote:
> >
> >>
> >> Does that explain the algorithm? I'm not against clarifying the comment,
> >> of course.
> >
> > Thanks a lot for this explanation. It's clear now.
> >
> >> I tried to do that, but I ran into troubles with the "date" tests. I
> >> needed to build values that close to the min/max values, so I did
> >> something like
> >>
> >> SELECT '4713-01-01 BC'::date + (i || ' days')::interval FROM
> >> generate_series(1,10) s(i);
> >>
> >> And then the same for the max date, but that fails because of the
> >> date/timestamp conversion in date plus operator.
> >>
> >> However, maybe two simple generate_series() would work ...
> >>
> >
> > Something like this? select i::date from  generate_series('4713-02-01
> > BC'::date,  '4713-01-01 BC'::date, '-1 day'::interval) i;
>
> That works, but if you try the same thing with the largest date, that'll
> fail
>
>   select i::date from  generate_series('5874896-12-01'::date,
>                                        '5874897-01-01'::date,
>                                        '1 day'::interval) i;
>
>   ERROR:  date out of range for timestamp

Hmm, I see. This uses generate_series(timestamp, timestamp, interval) version.

date + integer -> date though, so the following works. It's also an
example at https://www.postgresql.org/docs/16/functions-srf.html.
#SELECT '5874896-12-01'::date + i FROM
generate_series(1,10) s(i);

I think we should provide generate_series(date, date, integer) which
will use date + integer -> date.

-- 
Best Wishes,
Ashutosh Bapat

Commits

  1. Fix minmax-multi distance for extreme interval values

  2. Fix minmax-multi on infinite date/timestamp values

  3. Fix calculation in brin_minmax_multi_distance_date

  4. Fix overflow when calculating timestamp distance in BRIN