Re: Simple postgresql.conf wizard

On Wed, 3 Dec 2008, Robert Haas wrote:

> Then I tried "-T web" and got what seemed like a more reasonable set
> of values. But I wasn't sure I needed that many connections, so I
> added "-c 150" to see how much difference that made. Kaboom!

That and the import errors fixed in the version attached (just replacing
the script, not its data), thanks for testing that out.

> I'm not sure what "mixed" mode is supposed to be, but based on what
> I've seen so far, I'm a skeptical of the idea that encouraging people
> to raise default_statistics_target to 50 and turn on
> constraint_exclusion is reasonable.

The statistics stuff is obviously a broader discussion, will let that rage
in existing threads. The reason for setting constraint_exclusion in the
mixed case is that people who just pick the defaults without reading
anything will get a configuration that supports partitions usefully. One
of the HINTs I intend to throw out for that specific case is that they
should turn it off if they don't ever intend to use paritions.

The idea of the mixed mode is that you want to reduce the odds someone
will get a massively wrong configuration if they're not paying attention.
Is it worse to suffer from additional query overhead if you're sloppy with
the tuning tool, or to discover addition partitions didn't work as you
expected? That's a tough call; I could invert things, so that it defaults
to off in mixed mode, as always, and just produces a HINT to turn it on.
I don't have a really strong opinion there either way.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD