Re: Streaming Rep - 2-phase backups and reducing time to full replication

On Fri, 2009-12-25 at 14:33 +0900, Fujii Masao wrote:
> On Thu, Dec 24, 2009 at 6:03 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> > I see it would work like this: Add a new option to recovery.conf,
> > perhaps two_phase_backup = on. Startup creates a file called
> > backup_in_progress then waits. When second phase of backup is complete
> > (7b), delete the file and then Startup process will continue. Very few
> > lines of code to make this work.
> 
> Where do you think the WAL files shipped before doing (7b) are stored?
> If it's pg_xlog, the disk full failure would occur in the standby. If
> it's an archive, restore_command would have to be supplied the same as
> my idea.

Yes, agreed.

I am still concerned about the interactions at the start of replication.
It isn't clear how these things work exactly and as a result, I feel we
may be missing some better ideas.

Two points concern me
* When would sync rep be able to start?
* How do we avoid sending WAL twice?

-- Simon Riggs           www.2ndQuadrant.com