Re: SSI patch version 14

On Mon, 2011-01-24 at 21:30 -0600, Kevin Grittner wrote:

> Dan and I have spent many, many hours desk-check and testing,
> including pounding for many hours in DBT-2 at high concurrency
> factors on a 16 processor box. In doing so, we found and fixed a few
> issues. Neither of us is aware of any bugs or deficiencies
> remaining, even after a solid day of pounding in DBT-2, other than
> the failure to extend any new functionality to hot standby.

A couple of comments on this.

I looked at the patch to begin a review and immediately saw "dtest".
There's no docs to explain what it is, but a few comments fill me in a
little more. Can we document that please? And/or explain why its an
essential part of this commit? Could we keep it out of core, or if not,
just commit that part separately? I notice the code is currently
copyright someone else than PGDG.

Pounding for hours on 16 CPU box sounds good. What diagnostics or
instrumentation are included with the patch? How will we know whether
pounding for hours is actually touching all relevant parts of code? I've
done such things myself only to later realise I wasn't actually testing
the right piece of code.

When this runs in production, how will we know whether SSI is stuck or
is consuming too much memory? e.g. Is there a dynamic view e.g.
pg_prepared_xacts, or is there a log mode log_ssi_impact, etc??

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