Re: Impact of checkpoint_segments under continual load conditions - Mailing list pgsql-performance

From Christopher Petrilli
Subject Re: Impact of checkpoint_segments under continual load conditions
Date
Msg-id 59d991c405071811457ccdd3f1@mail.gmail.com
Whole thread Raw
In response to Re: Impact of checkpoint_segments under continual load conditions  (Vivek Khera <vivek@khera.org>)
Responses Re: Impact of checkpoint_segments under continual load conditions  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
On 7/18/05, Vivek Khera <vivek@khera.org> wrote:
>
> On Jul 17, 2005, at 1:08 PM, Christopher Petrilli wrote:
>
> > Normally, checkpoint_segments can help absorb some of that, but my
> > experience is that if I crank the number up, it simply delays the
> > impact, and when it occurs, it takes a VERY long time (minutes) to
> > clear.
>
> There comes a point where your only recourse is to throw hardware at
> the problem.  I would suspect that getting faster disks and splitting
> the checkpoint log to its own RAID partition would help you here.
> Adding more RAM while you're at it always does wonders for me :-)

My concern is less with absolute performance, than with the nosedive
it goes into.  I published some of my earlier findings and comparisons
on my blog, but there's a graph here:

http://blog.amber.org/diagrams/comparison_mysql_pgsql.png

Notice the VERY steep drop off.  I'm still trying to get rid of it,
but honestly, am not smart enough to know where it's originating.  I
have no desire to ever use MySQL, but it is a reference point, and
since I don't particularly need transactional integrity, a valid
comparison.

Chris
--
| Christopher Petrilli
| petrilli@gmail.com

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