Re: Streaming base backups

On Fri, Jan 7, 2011 at 02:15, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Wed, 2011-01-05 at 14:54 +0100, Magnus Hagander wrote:
>
>> The basic implementation is: Add a new command to the replication mode called
>> BASE_BACKUP, that will initiate a base backup, stream the contents (in tar
>> compatible format) of the data directory and all tablespaces, and then end
>> the base backup in a single operation.
>
> I'm a little dubious of the performance of that approach for some users,
> though it does seem a popular idea.

Well, it's of course only going to be an *option*. We should keep our
flexibility and allow the current ways as well.

> One very useful feature will be some way of confirming the number and
> size of files to transfer, so that the base backup client can find out
> the progress.

The patch already does this. Or rather, as it's coded it does this
once per tablespace.

It'll give you an approximation only of course, that can change, but
it should be enough for the purposes of a progress indication.

> It would also be good to avoid writing a backup_label file at all on the
> master, so there was no reason why multiple concurrent backups could not
> be taken. The current coding allows for the idea that the start and stop
> might be in different sessions, whereas here we know we are in one
> session.

Yeah, I have that on the todo list suggested by Heikki. I consider it
a later phase though.

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/