Re: Finding bottleneck

From: Merlin Moncure
Subject: Re: Finding bottleneck
Date: ,
Msg-id: 6EE64EF3AB31D5448D0007DD34EEB3417DCF28@Herge.rcsinc.local
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In response to: Finding bottleneck  (Kari Lavikka)
List: pgsql-performance

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Finding bottleneck  (Kari Lavikka, )
 Re: Finding bottleneck  (Gavin Sherry, )
 Re: Finding bottleneck  (Claus Guttesen, )
 Re: Finding bottleneck  ("Merlin Moncure", )
 Re: Finding bottleneck  ("Luke Lonergan", )
  Re: Finding bottleneck  (Kari Lavikka, )
   Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
  Re: Finding bottleneck  (Kari Lavikka, )
   Re: Finding bottleneck  (Tom Lane, )
    Re: Finding bottleneck  (Kari Lavikka, )
     Re: Finding bottleneck  (Tom Lane, )
    Re: Finding bottleneck  (Kari Lavikka, )
     Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  (Ron, )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )
 Re: Finding bottleneck  ("Merlin Moncure", )
  Re: Finding bottleneck  (Tom Lane, )
 Re: Finding bottleneck  ("Merlin Moncure", )

Kari Lavikka wrote:
> shared_buffers = 15000
you can play around with this one but in my experience it doesn't make
much difference anymore (it used to).

> work_mem = 1536                 # min 64, size in KB
this seems low.  are you sure you are not getting sorts swapped to disk?

> fsync = true                    # turns forced synchronization on or
off
does turning this to off make a difference?  This would help narrow down
where the problem is.

> commit_delay = 80000            # range 0-100000, in microseconds
hm! how did you arrive at this number?  try setting to zero and
comparing.

> stats_start_collector = true
> stats_command_string = true
with a high query load you may want to consider turning this off.  On
win32, I've had some problem with stat's collector under high load
conditions.  Not un unix, but it's something to look at.  Just turn off
stats for a while and see if it helps.

good luck! your hardware should be more than adequate.

Merlin


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From: "Luke Lonergan"
Date:
Subject: Re: Finding bottleneck
From: Karim Nassar
Date:
Subject: Two queries are better than one?