Horton

Re: BUG #17064: Parallel VACUUM operations cause the error "global/pg_filenode.map contains incorrect checksum"

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Thomas Munro <thomas.munro@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Alexander Lakhin <exclusion@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2021-06-23T00:41:19Z
Lists: pgsql-bugs 
Michael Paquier <michael@paquier.xyz> writes:
> On Tue, Jun 22, 2021 at 10:11:06AM -0400, Tom Lane wrote:
>> Shouldn't we instead file a kernel bug report?  I seem to recall that
>> POSIX guarantees atomicity of these things up to some operation size.
>> Or is that just for pipe I/O?

> Even if this is recognized as a bug report, it seems to me that we'd
> better cope with an extra lock for instances that may run into this
> issue anyway in the future, no?  Just to be on the safe side.

Based on the evidence at hand, we can't really say whether the writes
are non-atomic.  If that's the case then we have much worse problems
than just needing to add a lock.  Thus, I think we need to get some
kernel people involved.

			regards, tom lane

Commits

  1. Another fix to relmapper race condition.

  2. Prevent race condition while reading relmapper file.