Re: WIP partial replication patch

On Sat, Aug 14, 2010 at 08:40:24AM +0200, Boszormenyi Zoltan wrote:
> Andres Freund írta:
> > On Fri, Aug 13, 2010 at 09:36:00PM +0200, Boszormenyi Zoltan wrote:
> >
> >> Tom Lane írta:
> >>
> >>> Boszormenyi Zoltan <zb(at)cybertec(dot)at> writes:
> >>>
> >>>
> >>>> attached is a WIP patch that will eventually implement
> >>>> partial replication, with the following syntax:
> >>>>
> >>> This fundamentally cannot work, as it relies on system catalogs to be
> >>> valid during recovery.
> >>>
> >> Just like Hot Standby, no? What is the difference here?
> >> Sorry for being ignorant.
> >>
> > In HS you can only connect after youve found a restartpoint - only
> > after that you know that you have reached a consistent point for the
> > system.
> >
> And in this patch, the startup process only tries to connect
> after signalling the postmaster that a consistent state is reached.
> And the connection has a reasonable timeout built in.
I don't think you currently can guarantee you allways have enough local WAL to even reach
a consistent point. Which is not a problem of your patch, dont get me
wrong...

Andres