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

On Wed, Jun 20, 2012 at 10:08 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>>>> 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.

The bottleneck is getting the design right, not writing the code.
Selecting tasks for people to work on without an agreement on the
design will not advance the process, unless we just accept whatever
code you choose to right based on whatever design you happen to pick.

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

I estimated the amount of work that would be required to do this right
and compared it to other large projects that have been successfully
done in the past.  I think you are looking at something on the order
of magnitude of the Windows port, which took about four releases to
become stable, or the SE-Linux project, which still isn't
feature-complete.  Even if it's only a HS-sized project, that took two
releases, as did streaming replication.  SSI got committed within one
release cycle, but there were several years of design and advocacy
work before any code was written, so that, too, was really a
multi-year project.

I'll confine my comments on the second part of the question to the
observation that it is a bit early to know who is right and who is
wrong, but the question could just as easily be turned on its head.

> 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 think Kevin addressed this point better than I can.  Asserting
something doesn't make it true, and you haven't offered any rational
argument against the points that have been made, probably because
there isn't one.  We *cannot* justify steeling 100% of the available
bit space for a feature that many people won't use and may not be
enough to address the real requirement anyway.

> 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.

Participation in the community development process is not contingent
on having flown to Ottawa in May, or on having decided to spend that
evening at your briefing meeting.  Attributing to ignorance what is
adequately explained by honest disagreement is impolite.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company