From: | "Rangarajan Vasudevan" <ranga(at)asterdata(dot)com> |
---|---|
To: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Performance Tuning and Disk Cache |
Date: | 2007-03-18 18:22:30 |
Message-ID: | 53280.75.37.29.21.1174242150.squirrel@webmail.asterdata.net |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
If you are running on a Linux kernel, try /proc/sys/vm/drop_caches. I
believe the appropriate command is "echo 3 > /proc/sys/vm/drop_caches".
Since Postgres has its own cache of data, the above followed by a PG
restart should do what you are looking for.
Ranga
> Barry Moore wrote:
>
>> I have a very slow query that I'm trying to tune. I think my
>> performance tuning is being complicated by the system's page cache.
>>
>> If a run the query after the system has been busy with other tasks
>> for quite a long time then the query can take up to 8-10 minutes to
>> complete. If I then rerun the same query it will complete in a
>> couple of seconds.
>>
>> Does anyone know how I can repeatedly run the same query in the
>> "worst case scenario" of no postgres data in the disk cache (e.g.,
>> clear the page cache or force it to be ignored)?
>
> In my experience the only 100% reliable way to do this is to reboot the
> machine.
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
From | Date | Subject | |
---|---|---|---|
Next Message | Michael Stone | 2007-03-18 18:49:06 | Re: Performance Tuning and Disk Cache |
Previous Message | Martijn van Oosterhout | 2007-03-18 16:54:29 | Re: PostgreSQL 8.2.3 VACUUM Timings/Performance |