From: Andrei Lepikhov <a.lepikhov@postgrespro.ru>
To: Richard Guo <guofenglinux@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: zuming.jiang@inf.ethz.ch
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18260: Unexpected error: "negative bitmapset member not allowed" triggered by multiple JOIN
Date: Mon, 15 Jan 2024 07:20:37 +0700
Message-ID: <72b0913e-a2b1-444d-a2fa-fa154ae91034@postgrespro.ru> (raw)
In-Reply-To: <CAMbWs48k_meXFAH1qb9UiPS8Q_p-POWWW0DLpYtf2yiHht_ncA@mail.gmail.com>
References: <18260-1b6a0c4ae311b837@postgresql.org>
<CAMbWs4-tpHZyE-aEqhYt_aLtKU0YbcXBgz_GXG0EVHQXhSrENA@mail.gmail.com>
<CAMbWs4-7ZRRuaXpksRR2so3XW+gdRWPMiAuSGqdfgy9fFaUCDg@mail.gmail.com>
<ac1454ad-dc4d-467c-9a5a-11709ba33195@postgrespro.ru>
<CAMbWs48k_meXFAH1qb9UiPS8Q_p-POWWW0DLpYtf2yiHht_ncA@mail.gmail.com>
On 11/1/2024 16:08, Richard Guo wrote:
>
> On Thu, Dec 28, 2023 at 12:30 PM Andrei Lepikhov
> <a.lepikhov@postgrespro.ru <mailto:a.lepikhov@postgrespro.ru>> wrote:
>
> On 28/12/2023 10:03, Richard Guo wrote:
> > if (bms_is_subset(phinfo->ph_needed, joinrelids) &&
> > bms_is_member(relid, phinfo->ph_eval_at) &&
> > - !bms_is_member(ojrelid, phinfo->ph_eval_at))
> > + (sjinfo == NULL || !bms_is_member(ojrelid,
> phinfo->ph_eval_at)))
>
> > Alternatively, we can modify bms_is_member() to return false for
> > negative numbers instead of emitting an error, as suggested by the
> > comment there.
> > - /* XXX better to just return false for x<0 ? */
> > + /* negative number cannot be a member of the bitmapset */
> > if (x < 0)
> > - elog(ERROR, "negative bitmapset member not allowed");
> > + return false;
> >
> > I prefer the second option, but I'm open to other thoughts.
> I don't like this option. It could mask some blunders somewhere like a
> current one.
>
>
> After a second thought, I agree that the first option is better. It
> maintains consistency with the Assert a few lines ahead, and also
> minimizes the potential impact of code changes compared to the second
> option.
>
> > FWIW, here is a simplified repro for this error.
> >
> > create table t (a int primary key, b int);
> >
> > explain (verbose, costs off)
> > select 1 from t t1 left join
> > (lateral (select 1 as x, * from t t2) s1 inner join
> > (select * from t t3) s2 on s1.a = s2.a)
> > on true
> > where s1.x = 1;
> > ERROR: negative bitmapset member not allowed
> It can be simplified even more (without LATERAL):
>
>
> Indeed. I realized this shortly after v1 patch was sent out, and was
> thinking that it wasn't worth the effort to update the patch with a new
> version just for this issue.
I like it, thanks for your efforts.
--
regards,
Andrei Lepikhov
Postgres Professional
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To: pgsql-bugs@postgresql.org
Cc: a.lepikhov@postgrespro.ru, guofenglinux@gmail.com, aekorotkov@gmail.com, zuming.jiang@inf.ethz.ch, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18260: Unexpected error: "negative bitmapset member not allowed" triggered by multiple JOIN
In-Reply-To: <72b0913e-a2b1-444d-a2fa-fa154ae91034@postgrespro.ru>
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