Re: HOOKS for Synchronous Replication?

True, I think we need hooks for both methods.

On 12/8/05, Jan Wieck <JanWieck(at)yahoo(dot)com> wrote:
>
> On 12/8/2005 2:05 PM, Jim C. Nasby wrote:
>
> > On Thu, Dec 08, 2005 at 08:33:59AM -0800, Darcy Buskermolen wrote:
> >> On Wednesday 07 December 2005 20:24, Tom Lane wrote:
> >> > Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> writes:
> >> > > Anyone remember this patch?
> >> > > http://gorda.di.uminho.pt/community/pgsqlhooks/
> >> > > The discussion seems to be pretty minimal:
> >> > > http://archives.postgresql.org/pgsql-hackers/2005-06/msg00859.php
> >> > > Does anyone see a need to investigate it further?
> >> >
> >> > I had hoped to see some comments from the Slony people about it.
> >> > I'd feel better about the validity of a set of hooks if more than
> >> > one project agreed that it was useful/appropriate ...
> >>
> >> I missed seeing it all together the first time through, I'll see what I
> can do
> >> about taking a indepth look at it over the next few days and provide
> some
> >> feedback.
> >
> > While this code might be useful, whouldn't it be much more valuable to
> > provide hooks into xlog so that we could do non-trigger-based
> > replication? (As well as non-trigger-based materialized views...)
>
> I don't see why these would be mutually exclusive. A generic API needs
> to have them all.
>
> Without having looked at the patch yet, what I expect from an API is
> that the backend will (after initialization and becoming a member of a
> database) check if this database is replicated. If so load the specific
> shared object that implement the backend part of the replication system
> and then call an init() function in that. This init() function then will
> add callbacks to all the hooks where this particular replication system
> wants to be called. So one replication system might want to be called on
> commit, just before writing the WAL record, some other system doesn't
> care about that, but wants to see the WAL record after it was written.
>
>
> Jan
>
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