Re: Logical Replication Helpers WIP for discussion

On Mon, Dec 22, 2014 at 10:26 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Fri, Dec 19, 2014 at 8:40 AM, Petr Jelinek <petr(at)2ndquadrant(dot)com>
> wrote:
> > What I hope to get from this is agreement on the general approach and
> > protocol so that we can have common base which will both make it easier
> to
> > create external logical replication solutions and also eventually lead to
> > full logical replication inside core PostgreSQL.
>
> The protocol is a really important topic which deserves its own
> discussion. Andres has mentioned some of the ideas he has in mind -
> which I think are similar to what you did here - but there hasn't
> really been a thread devoted to discussing that topic specifically. I
> think that would be a good idea: lay out what you have in mind, and
> why, and solicit feedback.
>

Looking at this patch, I don't see what we actually gain much here except a
decoder plugin that speaks a special protocol for a special background
worker that has not been presented yet. What actually is the value of that
defined as a contrib/ module in-core. Note that we have already
test_decoding to basically test the logical decoding facility, used at
least at the SQL level to get logical changes decoded.

Based on those reasons I am planning to mark this as rejected (it has no
documentation as well). So please speak up if you think the contrary, but
it seems to me that this could live happily out of core.
--
Michael