Re: Core team statement on replication in PostgreSQL

On Fri, 2008-05-30 at 12:31 +0530, Gurjeet Singh wrote:
> On Fri, May 30, 2008 at 10:40 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>         But since you mention it: one of the plausible answers for
>         fixing the
>         vacuum problem for read-only slaves is to have the slaves push
>         an xmin
>         back upstream to the master to prevent premature vacuuming.
>          The current
>         design of pg_standby is utterly incapable of handling that
>         requirement.
>         So there might be an implementation dependency there,
>         depending on how
>         we want to solve that problem.
> 
> I think it would be best to not make the slave interfere with the
> master's operations; that's only going to increase the operational
> complexity of such a solution.
> 
> There could be multiple slaves following a master, some serving
> data-warehousing queries, some for load-balancing reads, some others
> just for disaster recovery, and then some just to mitigate human
> errors by re-applying the logs with a delay.

Agreed.

We ruled that out as the-only-solution a while back. It does have the
beauty of simplicity, so it may exist as an option or possibly the only
way, for 8.4.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support