Re: Why standby restores some WALs many times from archive?

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:

> On Sat, Dec 30, 2017 at 04:30:07AM +0300, Sergey Burladyan wrote:
> > We use this scripts:
> > https://github.com/avito-tech/dba-utils/tree/master/pg_archive
> >
> > But I can reproduce problem with simple cp & mv:
> > archive_command:
> > test ! -f /var/lib/postgresql/wals/%f && \
> > test ! -f /var/lib/postgresql/wals/%f.tmp && \
> > cp %p /var/lib/postgresql/wals/%f.tmp && \
> > mv /var/lib/postgresql/wals/%f.tmp /var/lib/postgresql/wals/%f
>
> This is unsafe. PostgreSQL expects the WAL segment archived to be
> flushed to disk once the archive command has returned its result to the
> backend.

Yes, you are right, thank you for pointing that out! I upload new
version with sync to github.

> Don't be surprised if you get corrupted instances or that you
> are not able to recover up to a consistent point if you need to roll in
> a backup.

But only if archive was reboot unexpectedly, am I right?

--
Sergey Burladyan