On Tue, Feb 19, 2019 at 9:44 PM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, Feb 19, 2019 at 04:27:02PM -0800, RSR999GMAILCOM wrote:
> > So wanted to clarify if this procedure really requires the WAL archive
> > location on a shared storage ?
>
> Shared storage for WAL archives is not a requirement. It is perfectly
> possible to use streaming replication to get correct WAL changes.
> Using an archive is recommended for some deployments and depending on
> your requirements and data retention policy, still you could have
> those archives on a different host and have the restore_command of the
> standbyt in recovery or the archive_command of the primary save the
> segments to it. Depending on the frequency new WAL segments are
> generated, this depends of course.
If I'm not mistaken, if you don't have WAL archive set up (a shared
filesystem isn't necessary, but the standby has to be able to restore
WAL segments from the archive), a few transactions that haven't been
streamed at primary shutdown could be lost, since the secondary won't
be able to stream anything after the primary has shut down. WAL
archive can always be restored even without a primary running, hence
why a WAL archive is needed.
Or am I missing something?