Re: Understanding tsearch2 performance

От: Oleg Bartunov
Тема: Re: Understanding tsearch2 performance
Дата: ,
Msg-id: Pine.LNX.4.64.1007141722480.32129@sn.sai.msu.ru
(см: обсуждение, исходный текст)
Ответ на: Re: Understanding tsearch2 performance  (Ivan Voras)
Ответы: Re: Understanding tsearch2 performance  (Ivan Voras)
Список: pgsql-performance

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Understanding tsearch2 performance  (Ivan Voras, )
 Re: Understanding tsearch2 performance  (Oleg Bartunov, )
  Re: Understanding tsearch2 performance  (Ivan Voras, )
   Re: Understanding tsearch2 performance  (Oleg Bartunov, )
    Re: Understanding tsearch2 performance  (Ivan Voras, )
     Re: Understanding tsearch2 performance  (Stephen Frost, )
      Re: Understanding tsearch2 performance  (Ivan Voras, )
 Re: Understanding tsearch2 performance  ("Kevin Grittner", )
  Re: Understanding tsearch2 performance  (Ivan Voras, )
   Re: Understanding tsearch2 performance  (Oleg Bartunov, )
   Re: Understanding tsearch2 performance  ("Kevin Grittner", )
    Re: Understanding tsearch2 performance  (Ivan Voras, )

On Wed, 14 Jul 2010, Ivan Voras wrote:

>> Returning 8449 rows could be quite long.
>
> You are right, I didn't test this. Issuing a query which returns a
> smaller result set is much faster.
>
> But, offtopic, why would returning 8500 records, each around 100 bytes
> long so around 8.5 MB, over local unix sockets, be so slow? The machine
> in question has a sustained memory bendwidth of nearly 10 GB/s. Does
> PostgreSQL spend much time marshalling the data through the socket stream?

It's disk access time.
in the very bad case it could take  ~5 ms (for fast drive) to get one just
one row.


     Regards,
         Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: , http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83


В списке pgsql-performance по дате сообщения:

От: Hannu Krosing
Дата:
Сообщение: Re: Need help in performance tuning.
От: Ivan Voras
Дата:
Сообщение: Re: Understanding tsearch2 performance