Horton

Re: A smaller default postgresql.conf

Jonah H. Harris <jonah.harris@gmail.com>

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From: "Jonah H. Harris" <jonah.harris@gmail.com>
To: "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Cc: "Josh Berkus" <josh@agliodbs.com>, "Tom Lane" <tgl@sss.pgh.pa.us>, "Alvaro Herrera" <alvherre@commandprompt.com>, "Joshua Drake" <jd@commandprompt.com>, "Hans-Juergen Schoenig" <postgres@cybertec.at>, "Peter Eisentraut" <peter_e@gmx.net>, "Magnus Hagander" <magnus@hagander.net>, pgsql-hackers@postgresql.org
Date: 2008-08-19T17:24:07Z
Lists: pgsql-hackers 
On Tue, Aug 19, 2008 at 1:17 PM, Kevin Grittner
<Kevin.Grittner@wicourts.gov> wrote:
>> Josh Berkus <josh@agliodbs.com> wrote:
> But I'm amazed by this, too:
>
> # max_connections = 700  # web application database
>
> How many CPUs and spindles are you assuming there?
>
> My testing and experience suggest applications should use no more than
> 4 per CPU plus 2 per spindle, absolute maximum.  Don't you find that a
> connection pool with queuing capability is required for best
> performance with a large number of users?

Agreed, with this many concurrent users, I would expect severe lock
contention on the ProcArrayLock.  Similarly, if this were heavily
updated, WAL-related locks would likely become another significant
bottleneck.

-- 
Jonah H. Harris, Senior DBA
myYearbook.com