Re: How clear the cache on postgresql?

Hi,

A way to trick EXPLAIN/EXPLAIN ANALYZE to do what you mean is to play
with the optimisation variables:

https://www.postgresql.org/docs/9.6/static/runtime-config-query.html

J.

On 25 November 2017 at 15:01, Adam Tauno Williams
<awilliam(at)whitemice(dot)org> wrote:
> On Fri, 2017-11-24 at 11:58 -0800, John R Pierce wrote:
>> On 11/24/2017 11:43 AM, Michael Nolan wrote:
>> > There are so many different levels of caching going on--within
>> > Postgresql, within the OS, within a disk array or SAN, and at the
>> > individual drive--that there may no longer be a meaningful way to
>> > perform this measurement.
>> generally, power cycling the server will flush all the hardware
>> caches AND the OS cache.
>
> Given that a real-world application will almost never experience an
> empty-cache scenario I question the usefulness of clearing the
> cache(s). I would capture transactions from a production database in
> order to create a load test that mimics real-world load.
>
> --
> Meetings Coordinator, Michigan Association of Railroad Passengers
> 537 Shirley St NE Grand Rapids, MI 49503-1754 Phone: 616.581.8010
> E-mail: awilliam(at)whitemice(dot)org GPG#D95ED383 Web: http://www.marp.org
>

--
Jerome Eteve
http://www.justgiving.com/jetevesober
+44(0)7738864546
http://www.eteve.net/