Re: reducing the overhead of frequent table locks - now, with WIP patch

On Tue, Jun 7, 2011 at 7:55 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> Before you arrived, it was quite normal to suggest tuning patches
>> after feature freeze.
>
> *Low risk* tuning patches make sense at this stage, yes.  Fooling with
> the lock mechanisms doesn't qualify as low risk in my book.  The
> probability of undetected subtle problems is just too great.

Good, then we do agree. Some things are allowed, with suitable
justification. That has not been a point accepted by everybody here
though.

Upthread, I proposed that we leave Robert's patch until 9.2. That was
*after* I had reviewed it for impact and risk. I agree, its High Risk,
and so must be put off until normal dev opens because of the
sensitivity and criticality of getting the locking interactions right.

Moving on from that, I have proposed other solutions. Koichi, Jignesh
and and then Robert have shown measurements of the huge contention in
this area of our software. Robert's patch addresses the problems, as
do Koichi's and my latest patch. I would like to see us do
*something* about these problems for 9.1. Not all of them are risky or
time consuming. I'm clearly not alone in this thought; Dave, Dimitri
and Koichi-san have also spoken in favour of action for this release.

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