Re: Mapping a database completly into Memory

Поиск
Список
Период
Сортировка
От Bruce Momjian
Тема Re: Mapping a database completly into Memory
Дата
Msg-id 200307302210.h6UMAOp15472@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: Mapping a database completly into Memory  (Vivek Khera <khera@kcilink.com>)
Ответы Re: Mapping a database completly into Memory  (Vivek Khera <khera@kcilink.com>)
Список pgsql-performance
I think it all depends on your working set.  Having shared memory be
smaller than you working set causes pages to have to be copied in from
the kernel buffers (not a huge problem, but a small penalty), while
having shared memory larger than the working set causes overhead of
searching through all those buffers.

---------------------------------------------------------------------------

Vivek Khera wrote:
> >>>>> "TL" == Tom Lane <tgl@sss.pgh.pa.us> writes:
>
> TL> Franco Bruno Borghesi <franco@akyasociados.com.ar> writes:
> >> wouldn't also increasing shared_buffers to 64 or 128 MB be a good
> >> performance improvement? This way, pages belonging to heavily used
> >> indexes would be already cached by the database itself.
>
> TL> Not necessarily.  The trouble with large shared_buffers settings is you
> TL> end up with lots of pages being doubly cached (both in PG's buffers and
>
> I think if you do a lot of inserting/updating to your table, then more
> SHM is better (and very high fsm settings), since you defer pushing
> out the dirty pages to the disk.  For read-mostly, I agree that
> letting the OS do the caching is a better way.
>
>
> --
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> Vivek Khera, Ph.D.                Khera Communications, Inc.
> Internet: khera@kciLink.com       Rockville, MD       +1-240-453-8497
> AIM: vivekkhera Y!: vivek_khera   http://www.khera.org/~vivek/
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
>       subscribe-nomail command to majordomo@postgresql.org so that your
>       message can get through to the mailing list cleanly
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

В списке pgsql-performance по дате отправления:

Предыдущее
От: Josh Berkus
Дата:
Сообщение: Re: postgresql.conf
Следующее
От: Bruce Momjian
Дата:
Сообщение: Re: Mapping a database completly into Memory