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In-Reply-To: <8a547c841002252212t382cfeb4pde3e668a9d3f2f10@mail.gmail.com>
References: <8a547c841002252212t382cfeb4pde3e668a9d3f2f10@mail.gmail.com>
Date: Thu, 25 Feb 2010 22:20:38 -0800
Message-ID: <8a547c841002252220o4579ead0vd35a44726fdd5c5f@mail.gmail.com>
Subject: Re: bgwriter, checkpoints, curious (seeing delays)
From: Tory M Blue <tmblue@gmail.com>
To: pgsql-performance@postgresql.org
Content-Type: text/plain; charset=ISO-8859-1

On Thu, Feb 25, 2010 at 10:12 PM, Tory M Blue <tmblue@gmail.com> wrote:
> Okay ladies and gents and the rest of you :)
>
> It's time I dig into another issue, and that's a curious 5 second
> delay on connect, on occasion. Now, I believe the network to be sound
> and there are zero errors on any servers, no retrans, no runts, nada
> nada nada. However I will continue to run tests with/without dns,
> tcpdumps, tracking communications, handshakes, however.
>
> I've been doing some reading and what did I find. I found "Checkpoints
> are very disrupting to your database performance and can cause
> connections to stall for up to a few seconds while they occur."

Quick added note, sorry.

"checkpoint_completion_target (floating point)

    Specifies the target length of checkpoints, as a fraction of the
checkpoint interval. The default is 0.5. This parameter can only be
set in the postgresql.conf file or on the server command line. "

interesting that it's a .5 second default setting and I'm seeing
exactly that .5 second delay.

Again could be reaching here!

Thanks for putting up with me

Tory