Re: Synchronous Log Shipping Replication

On Mon, 2008-09-08 at 19:19 +0900, ITAGAKI Takahiro wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> > > > b) Use new background process as WALSender
> > > >
> > > > This idea needs background-process hook which enables users
> > > > to define new background processes
>
> > I think starting/stopping a process for each WAL send is too much
> > overhead.
>
> Yes, of course slow. But I guess it is the only way to share one socket
> in all backends. Postgres is not a multi-threaded architecture,
> so each backend should use dedicated connections to send WAL buffers.
> 300 backends require 300 connections for each slave... it's not good at all.

So... don't have individual backends do the sending. Have them wait
while somebody else does it for them.

> > It sounds like Fujii-san is basically saying they can only get the hooks
> > done for 8.4, not the actual solution.
>
> No! He has an actual solution in his prototype ;-)

The usual thing if you have a WIP patch you're not sure of is to post
the patch for feedback.

If you guys aren't going to post any code to the project then I'm not
clear why it's being discussed here. Is this a community project or a
private project?

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