Re: Re: PANIC: invalid index offnum: 186 when processing BRIN indexes in VACUUM

On Mon, Oct 30, 2017 at 9:42 AM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> Tomas Vondra wrote:
>> FWIW I can reproduce this on REL_10_STABLE, but not on REL9_6_STABLE. So
>> it seems to be due to something that changed in the last release.
>
> I've been trying to reproduce it for half an hour with no success (I
> think my laptop is just too slow). I bet this is related to the
> addition of PageIndexTupleOverwrite (commit b1328d78f) though I find it
> more likely that this was not *caused* by that commit but rather just
> made it easier to hit.

b1328d78f is close enough, but per what I see that's actually not
true. I have been able to reproduce the problem, which shows up within
a window of 2-4 minutes. Still sometimes it can take way longer, and I
spotted one test where it took 15 minutes to show up... So, bisecting
with a test that looks for core files for 20 minutes, I am seeing that
the following commit is actually at fault:
commit 24992c6db9fd40f342db1f22747ec9e56483796d
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Date: Fri Sep 9 19:00:59 2016 -0400

Rewrite PageIndexDeleteNoCompact into a form that only deletes 1 tuple.

The full generality of deleting an arbitrary number of tuples is no longer
needed, so let's save some code and cycles by replacing the original coding
with an implementation based on PageIndexTupleDelete.
--
Michael