Re: Final background writer cleanup for 8.3

Greg,

> As far as I'm concerned, that function of the background writer has been
> replaced by the load distributed checkpoint features now controlled by
> checkpoint_completion_target, which is believed to be a better solution
> in several respects. I'm been trying to motivate people happily using
> the current background writer to confirm or deny that during beta, while
> there's still time to put the all-scan portion that was removed back
> again.

In about 200 benchmark test runs, I don't feel like we ever came up with a
set of bgwriter settings we'd happily recommend to others. SO it's hard
for me to tell whether this is true or not.

> The open issue I'm working on is whether the LRU cleaner running in
> advance of the Strategy point is still a worthwhile addition on top of
> that.
>
> My own tests with pgbench that I'm busy wrapping up today haven't
> provided many strong conclusions here; the raw data is now on-line at
> http://www.westnet.com/~gsmith/content/bgwriter/ , am working on
> summarizing it usefully and bundling the toolchain I used to run all
> those. I'll take a look at whether TCP-W provides a helpfully different
> view here because as far as I'm aware that's a test neither myself or
> Heikki has tried yet to investigate this area.

Can you send me the current version of the patch, plus some bgwriter
settings to try with it, so we can throw it on some of the Sun benchmarks?

--
--Josh

Josh Berkus
PostgreSQL @ Sun
San Francisco