Re: Understanding tsearch2 performance

От: Ivan Voras
Тема: Re: Understanding tsearch2 performance
Дата: ,
Msg-id: i1kc3m$ngr$1@dough.gmane.org
(см: обсуждение, исходный текст)
Ответ на: Re: Understanding tsearch2 performance  (Oleg Bartunov)
Ответы: Re: Understanding tsearch2 performance  (Oleg Bartunov)
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 07/14/10 14:31, Oleg Bartunov wrote:
> Something is not good with statistics,  91 est. vs 8449 actually returned.

I don't think the statistics difference is significant - it's actually
using the index so it's ok. And I've run vacuum analyze just before
starting the query.

> 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?


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