Re: [patch] reorder tablespaces in basebackup tar stream for backup_label

Hi,

Am Mittwoch, den 29.03.2017, 15:22 +0900 schrieb Michael Paquier:
> On Wed, Mar 29, 2017 at 3:56 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> > If your need other information except START WAL LOCATION at the beginning of
> > base backup and they are very useful for many third-party softwares,
> > you can add them into that first result set. If you do this, you can
> > retrieve them
> > at the beginning even when WAL files are included in the backup.
>
> You mean in the result tuple of pg_start_backup(), right? Why not.

The replication protocol chapter says: "When the backup is started, the
server will first send two ordinary result sets, followed by one or more
CopyResponse results. The first ordinary result set contains the
starting position of the backup, in a single row with two columns."

However, I don't think it is very obvious to users (or at least it is
not to me) how to get at this from psql, if you want to script it. If I
run something like 'psql "dbname=postgres replication=database" -c
"BASE_BACKUP" "> foo', I seem to only get the tar file(s), unless I am
missing something.

The reason one might not want to run pg_basebackup directly is that this
way one can pipe the output to an external program, e.g. to better
compress it; this is not possible with pg_basebackup if you additional
tablespaces.

So I think that has some merit on its own.

Michael

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