Re: pg_basebackup for streaming base backups

On Thu, Jan 20, 2011 at 16:45, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> Robert Haas wrote:
>> > I read the description as:
>> >
>> > + ? ?You can also use the <xref linkend="app-pgbasebackup"> tool to take
>> > + ? ?the backup, instead of manually copying the files. This tool will take
>> > + ? ?care of the <function>pg_start_backup()</>, copy and
>> > + ? ?<function>pg_stop_backup()</> steps automatically, and transfers the
>> > + ? ?backup over a regular <productname>PostgreSQL</productname> connection
>> > + ? ?using the replication protocol, instead of requiring filesystem level
>> > + ? ?access.
>> >
>> > so I thought, well it does pg_start_backup and pg_stop_backup, and also
>> > creates the data directory.
>>
>> Yeah, but pg_start_backup() and pg_stop_backup() are server functions,
>> and this is an application.
>>
>> Also, it won't actually work unless the server has replication
>> configured (wal_level!=minimal, max_wal_senders>0, and possibly some
>> setting for wal_keep_segments), which has been the main point of the
>> naming discussion thus far.  Now, you know what would be REALLY cool?
>> Making this work without any special advance configuration.  Like if
>> we somehow figured out a way to make max_wal_senders unnecessary, and
>> a way to change wal_level without bouncing the server, so that we
>> could temporarily boost the WAL level from minimal to archive if
>> someone's running a backup.
>>
>> That, however, is not going to happen for 9.1... but it would be
>> *really* cool.
>
> Well, when we originally implemented PITR, we could have found a way to
> avoid using SQL commands to start/stop backup, but we envisioned that we
> would want to hook things on to those commands so we created a stable
> API that we could improve, and we have.

Yeah, we're certianly not taking those *away*.

> Do we envision pg_basebackup as something we will enahance, and if so,
> should we consider a generic name?

Well, it's certainly going to be enhanced. I think there are two main
uses for it - backups, and setting up replication slaves. I can't see
it expanding beyond those, really.

--
 Magnus Hagander
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