Re: buildfarm: could not read block 3 in file "base/16384/2662": read only 0 of 8192 bytes

Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> On Wed, Jul 25, 2018 at 4:07 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> I don't immediately see it being responsible, but I wonder if there's a
>> chance it actually is: Note that it happens in a parallel group that
>> includes vacuum.sql, which does a VACUUM FULL pg_class - but I still
>> don't immediately see how it could apply.

> Anyway, "VACUUM FULL pg_class" should be expected to corrupt
> pg_class_oid_index when we happen to get a parallel build, since
> pg_class is a mapped relation, and I've identified that as a problem
> for parallel CREATE INDEX [2]. If that was the ultimate cause of the
> issue, it would explain why only REL_11_STABLE and master are
> involved.

Oooh ... but pg_class wouldn't be big enough to get a parallel
index rebuild during that test, would it?

regards, tom lane