Re: Integrating Replication into Core

On Thu, 2006-11-23 at 08:50 +0100, Markus Schiltknecht wrote:
> Hi,
>
> Jeff Davis wrote:
> > I think you misunderstand my point.
>
> That may well be. Please keep in mind that I'm not a native English
> speaker, thus please speak loud and clear ;-)
>
> > I was talking about replication
> > implementations that already exist. They already have patches on the
> > backend that are necessary for their solution to work.
>
> Do they? I'm only aware of the GORDA patch. The old Postgres-R patches
> are out of date. Sequoia, PgPool and PgPool-II obviously do not need
> patches. Slony-II, Postgres-R (8) (mine) as well as PGCluster-II are not
> open sourced, yet. And I haven't heard much regarding hooks from any of
> the proprietary vendors (except Joshua's recent statement that he's
> happy without such hooks).

Because we're talking about replication, I don't think we can limit the
discussion to current open source solutions. I could be mistaken, but I
am under the impression that commercial replication solutions do patch
the backend.

> > The idea is to design a single set of hooks that can be used to
> > implement an entire class of replication. This only makes sense after
> > existing solutions come to some agreement. I view that as a first step,
> > assuming that it is necessary to alter the core in order to implement
> > the class of replication in question.
>
> As there's not even *one* existing and open replication solution which
> needs patching the backend, you are basing your statements on a false
> premise. Thus, speaking of hooks as a "first step" is very confusing, at
> least.
>

You're right, there is no agreement yet. When I say "first step," I mean
that it's the first step toward getting any form of replication support
in the _backend_, _not_ a first step toward a replication solution at
all. It may be a long time before the backend has replication-specific
support of any kind, but many replication projects have passed the first
step toward replication a long time ago.

I am not advocating replication support in the backend (since I don't
even know what form that would take), nor am I saying that it will
appear soon. I am just saying that replication-specific syntax is
unlikely to appear before other replication-specific details.

Regards,
Jeff Davis