From: | Amul Sul <sulamul(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Noah Misch <noah(at)leadboat(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Neha Sharma <neha(dot)sharma(at)enterprisedb(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [CLOBBER_CACHE]Server crashed with segfault 11 while executing clusterdb |
Date: | 2021-03-24 05:40:08 |
Message-ID: | CAAJ_b94tVyuZ=HvGbznv8WNZGzT_fmOJUbFfnKskP_mF17AN_w@mail.gmail.com |
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On Tue, Mar 23, 2021 at 8:59 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> I wrote:
> > Michael Paquier <michael(at)paquier(dot)xyz> writes:
> >> One bisect later, the winner is:
> >> commit: 3d351d916b20534f973eda760cde17d96545d4c4
> >> author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> >> date: Sun, 30 Aug 2020 12:21:51 -0400
> >> Redefine pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.
>
> > I think that's an artifact. That commit didn't touch anything related to
> > relation opening or closing. What it could have done, though, is change
> > CLUSTER's behavior on this empty table from use-an-index to use-a-seqscan,
> > thus causing us to follow the buggy code path where before we didn't.
>
> On closer inspection, I believe the true culprit is c6b92041d,
> which did this:
>
> */
> if (RelationNeedsWAL(state->rs_new_rel))
> - heap_sync(state->rs_new_rel);
> + smgrimmedsync(state->rs_new_rel->rd_smgr, MAIN_FORKNUM);
>
> logical_end_heap_rewrite(state);
>
> heap_sync was careful about opening rd_smgr, the new code not so much.
>
> I read the rest of that commit and didn't see any other equivalent
> bugs, but I might've missed something.
>
I too didn't find any other place replacing heap_sync() or equivalent place from
this commit where smgr* operation reaches without necessary precautions call.
heap_sync() was calling RelationOpenSmgr() through FlushRelationBuffers() before
it reached smgrimmedsync(). So we also need to make sure of the
RelationOpenSmgr() call before smgrimmedsync() as proposed previously.
Regards,
Amul
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