Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node

On 20 June 2012 21:42, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Jun 20, 2012 at 9:25 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> On 20 June 2012 21:19, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Wed, Jun 20, 2012 at 5:47 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>>>> 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.
>>>
>>> If you're saying that single-master logical replication isn't useful,
>>> I disagree.  Of course, having both single-master and multi-master
>>> replication together is even more useful.
>>
>>> But I think getting even
>>> single-master logical replication working well in a single release
>>> cycle is going to be a job and a half.
>>
>> OK, so your estimate is 1.5 people to do that. And if we have more
>> people, should they sit around doing nothing?
>
> Oh, give me a break.  You're willfully missing my point.  And to quote
> Fred Brooks, nine women can't make a baby in one month.

No, I'm not. The question is not how quickly can N people achieve a
single thing, but how long will it take a few skilled people working
on carefully selected tasks that have few dependencies between them to
achieve something.

We have significantly more preparation, development time and resources
than any other project previously performed for PostgreSQL, that I am
aware of.

Stating that it is impossible to perform a task in a certain period of
time without even considering those points is clearly rubbish. I've
arrived at my thinking based upon detailed project planning of what
was possible in the time.

How exactly did you arrive at your conclusion? Why is yours right and
mine wrong?

>>> Thinking that we're going to
>>> get MMR in one release is not realistic.
>>
>> If you block it, then the above becomes true, whether or not it starts true.
>
> If I had no rational basis for my objections, that would be true.
> You've got four people objecting to this patch now, all of whom happen
> to be committers.  Whether or not MMR goes into core, who knows, but
> it doesn't seem that this patch is going to fly.

No, I have four people who had initial objections and who have not
commented on the fact that the points made are regrettably incorrect.
I don't expect everybody commenting on the design to have perfect
knowledge of the whole design, so I expect people to make errors in
their comments. I also expect people to take note of what has been
said before making further objections or drawing conclusions.

Since at least 3 of the people making such comments did not attend the
full briefing meeting in Ottawa, I am not particularly surprised.
However, I do expect people that didn't come to the meeting to
recognise that they are likely to be missing information and to listen
closely, as I listen to them.

"When the facts change, I change my mind. What do you do, sir?"

> My main point in bringing this up is that if you pick a project that
> is too large, you will fail.  As I would rather see this project
> succeed, I recommend that you don't do that.  Both you and Andres seem
> to believe that MMR is a reasonable first target to shoot at, but I
> don't think anyone else - including the Slony developers who have
> commented on this issue - endorses that position.  At PGCon, you were
> talking about getting a new set of features into PG over the next 3-5
> years.  Now, it seems like you want to compress that timeline to a
> year.  I don't think that's going to work.  You also requested that
> people tell you sooner when large patches were in danger of not making
> the release.  Now I'm doing that, VERY early, and you're apparently
> angry about it.  If the only satisfactory outcome of this conversation
> is that everyone agrees with the design pattern you've already decided
> on, then you haven't left yourself very much room to walk away
> satisfied.

Note that I have already myself given review feedback to Andres and
that change has visibly occurred during this thread via public debate.

Claiming that I only stick to what has already been decided is
patently false, with me at least.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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