От: Andres Freund
Тема: Re: random slow query
Дата: ,
Msg-id: 4A48C345.2060704@anarazel.de
(см: обсуждение, исходный текст)
Ответ на: random slow query  (Sean Ma)
Список: pgsql-performance

Скрыть дерево обсуждения

random slow query  (Sean Ma, )
 Re: random slow query  (Andres Freund, )
 Re: random slow query  ("Kevin Grittner", )
 Re: random slow query  (Mike Ivanov, )
  Re: random slow query  (Sean Ma, )
   Re: random slow query  (Mike Ivanov, )
    Re: random slow query  (Scott Marlowe, )
     Re: random slow query  (Mike Ivanov, )
      Re: random slow query  (Scott Marlowe, )
       Re: random slow query  (Mike Ivanov, )
      Re: random slow query  (Scott Marlowe, )
       Re: random slow query  (Mike Ivanov, )
      Re: random slow query  (Alan Hodgson, )
       Re: random slow query  (Jean-David Beyer, )
        Re: random slow query  (Scott Carey, )
      Re: random slow query  (Scott Carey, )
       Re: random slow query  (Scott Carey, )
       Re: random slow query  (Mike Ivanov, )
        Re: random slow query  (Scott Carey, )
         Re: random slow query  (Mike Ivanov, )
    Re: random slow query  (Sean Ma, )
     Re: random slow query  (Scott Marlowe, )
      Re: random slow query  (Mike Ivanov, )
       Re: random slow query  (Scott Marlowe, )
     Re: random slow query  (Mike Ivanov, )

On 06/29/2009 03:33 PM, Sean Ma wrote:
> I have a table about 50 million rows. There are a few writers to pump
> data into the table at the rate of 40000 row/hours. Most the time, the
> SELECT is less than 100 ms. However sometime it is very slow, from 30
> seconds to 500 seconds. The database is vacuum analyze regularly.
>
> One months ago, this type of slow query happened about a few time per
> day. But recently, the slow query happens more frequent at the rate of
> once every 10 minutes or less. There seesm not relation to the
> database loading or the type of query. If I manually execute these
> query, it is returns in less than 1 seconds.
>
> I just wonder where should I start to look?
The slow queries could be waiting for locks - so you could enable
log_lock_waits to see if that is the issue.

Andres



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