Re: Stale description for pg_basebackup

Ugg. I was confused.


At Wed, 21 Apr 2021 23:06:56 +0900, Fujii Masao <masao.fujii@oss.nttdata.com> wrote in 
> > Hmm. Some words need to be qualified. Attached.
> 
> + If you are using <literal>-X none</literal>, there is no guarantee
> on
> + the primary that all WAL files required for the backup are archived
> at
> +       the end of backup.
> 
> I don't think that this should be picked up as a limitation of standby
> backup.
> Because users basically want to make pg_basebackup wait for all
> required
> WAL files to be archived on the standby, in the standby backup case.

Yeah, you're right. I think it is what I thought at first. The last
proposal is a result of some confusion..

> When <varname>archive_mode</varname> is set
> +       to <literal>on</literal> on the
> 
> "on" should be "always"?

Yes..

> + standby, <application>pg_basebackup</application> may wait for a
> long
> + time for all the required WAL files to be archived.  In that case,
> You
> + may need to call <function>pg_switch_wal()</function> on the primary
> to
> +       complete it sooner.
> 
> What about the following description?
> 
> -------------------
> When you are using -X none, if write activity on the primary is low,
> pg_basebackup may need to wait a long time for all WAL files required
> for
> the backup to be archived. It may be useful to run pg_switch_wal
> on the primary in order to trigger an immediate WAL file switch and
> archiving.
> -------------------

Looks far better.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center