Re: Synchronous Log Shipping Replication

Hannu Krosing escribió:
> On Fri, 2008-09-12 at 17:45 +0100, Simon Riggs wrote:
> > On Fri, 2008-09-12 at 17:11 +0200, Csaba Nagy wrote:
> > 
> > > Why not have a design where the slave is in control for it's own data ?
> > > I mean the slave...
> > 
> > The slave only exists because it is a copy of the master. If you try to
> > "startup" a slave without first having taken a copy, how would you
> > bootstrap the slave? With what? To what? 
> 
> As I understand it, Csaba meant that slave would "bootstrap itself" by
> connecting to master in some early phase of startup, requesting a
> physical filesystem level copy of data, then commencing the startup in
> Hot Standby mode.

Interesting ...

This doesn't seem all that difficult -- all you need is to start one
connection to get the WAL stream and save it somewhere; meanwhile a
second connection uses a combination of pg_file_read on master +
pg_file_write on slave to copy the data files over.  When this step is
complete, recovery of the stored WAL commences.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support