Re: Performance Tuning and Disk Cache

От: David Boreham
Тема: Re: Performance Tuning and Disk Cache
Дата: ,
Msg-id: 45FD5A2D.2090307@boreham.org
(см: обсуждение, исходный текст)
Ответ на: Performance Tuning and Disk Cache  (Barry Moore)
Ответы: Re: Performance Tuning and Disk Cache  ("Rangarajan Vasudevan")
Список: pgsql-performance

Скрыть дерево обсуждения

Performance Tuning and Disk Cache  (Barry Moore, )
 Re: Performance Tuning and Disk Cache  ("hubert depesz lubaczewski", )
 Re: Performance Tuning and Disk Cache  (David Boreham, )
  Re: Performance Tuning and Disk Cache  ("Rangarajan Vasudevan", )
 Re: Performance Tuning and Disk Cache  (Michael Stone, )

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.




В списке pgsql-performance по дате сообщения:

От: Michael Stone
Дата:
Сообщение: Re: Performance Tuning and Disk Cache
От: Tom Lane
Дата:
Сообщение: Re: function call vs staright query