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Re: What does \timing measure?

From: Mathieu Dubois <mathieu(dot)dubois(at)limsi(dot)fr>
To: pgsql-novice(at)postgresql(dot)org
Subject: Re: What does \timing measure?
Date: 2011-04-11 17:19:09
Message-ID: 4DA3380D.4010701@limsi.fr (view raw or flat)
Thread:
Lists: pgsql-novice
Hello,

Sorry for the delay.

I spent time writing a short script shell to do this (see attachment). 
This script has to be run on the server. Be aware that you can very 
easily destroy your DB with it.

The query can be either in a file (specified with -i FILENAME) or from 
the CLI (between ' ').

Thank you very much.
Mathieu

On 04/08/2011 03:02 PM, Josh Kupershmidt wrote:
> On Fri, Apr 8, 2011 at 2:31 AM, Mathieu Dubois<mathieu(dot)dubois(at)limsi(dot)fr>  wrote:
>> Yes I'm really interested in the "cold query time".
>> Is restarting PostgreSQL mandatory? What about just log out (from
>> PostgreSQL), wait some time (let's say 1mn) and then relog?
> Logging out from Postgres isn't going to do anything to clear its
> buffercache. AFAIK the only way to wipe it is to shutdown the server
> and start it back up.
>
>> Also a quick googling shows that to clear OS cache I can run (on the
>> server):
>>
>> sync;
>> sysctrl -w vm.drop_caches=3;
>>
>> Is that right?
> I believe that's right, if you're on Linux with a recent kernel.
>
> Josh
>


Attachment: test_query
Description: text/plain (956 bytes)

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