Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node
Date
Msg-id CA+U5nMKF8fofo+ntv5E8skYjTt5_V+Vp3x1Z5yz8pj0qhHwYuQ@mail.gmail.com
Whole thread Raw
In response to Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node
List pgsql-hackers
On 20 June 2012 16:44, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> On 20.06.2012 11:34, Simon Riggs wrote:
>>
>> On 20 June 2012 16:23, Heikki Linnakangas
>> <heikki.linnakangas@enterprisedb.com>  wrote:
>>
>>> It's only needed for multi-master replication, where the same table can
>>> be
>>> updated from multiple nodes. Just leave that out for now. There's plenty
>>> of
>>> functionality and issues left even without that.
>>
>>
>> Huh? Multi-master replication is what is being built here and many
>> people want that.
>
>
> Sure, but presumably you're going to implement master-slave first, and build
> multi-master on top of that. What I'm saying is that we can leave out the
> origin-id for now, since we don't have agreement on it, and revisit it after
> master-slave replication is working.

I am comfortable with the idea of deferring applying the patch, but I
don't see any need to defer agreeing the patch is OK, so it can be
applied easily later. It does beg the question of when exactly we
would defer it to though. When would that be?

If you have a reason for disagreement, please raise it now, having
seen explanations/comments on various concerns. Of course, people have
made initial objections, which is fine but its not reasonable to
assume that such complaints continue to exist after. Perhaps there are
other thoughts?

The idea that logical rep is some kind of useful end goal in itself is
slightly misleading. If the thought is to block multi-master
completely on that basis, that would be a shame. Logical rep is the
mechanism for implementing multi-master.

Deferring this could easily end up with a huge patch in last CF, and
then it will be rejected/deferred. Patch submission here is following
the requested process - as early as possible, production ready, small
meaningful patches that build towards a final goal. This is especially
true for format changes, which is why this patch is here now. Doing it
differently just makes patch wrangling and review more difficult,
which reduces overall quality and slows down development.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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