Re: strange performance regression between 7.4 and 8.1

From: Guido Neitzer
Subject: Re: strange performance regression between 7.4 and 8.1
Date: ,
Msg-id: 2EB9B5FC-E7D5-46A7-8068-6C5D059E7781@event-s.net
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In response to: Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher")
Responses: Re: strange performance regression between 7.4 and 8.1  (Jeff Frost)
List: pgsql-performance

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strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
 Re: strange performance regression between 7.4 and 8.1  ("Joshua D. Drake", )
  Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
   Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
    Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
   Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
    Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
     Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
      Re: strange performance regression between 7.4 and 8.1  (Tom Lane, )
       Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
  Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
   Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
    Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
     Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
      Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
       Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
        Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
         Re: strange performance regression between 7.4 and 8.1  ("Joshua D. Drake", )
          Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
           Re: strange performance regression between 7.4 and 8.1  ("Joshua D. Drake", )
            Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
         Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
          Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
 Re: strange performance regression between 7.4 and 8.1  (Ron, )
 Re: strange performance regression between 7.4 and 8.1  (Florian Weimer, )
  Re: strange performance regression between 7.4 and 8.1  (Carlos Moreno, )
   Re: strange performance regression between 7.4 and 8.1  (Ron, )
  Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
  Re: strange performance regression between 7.4 and 8.1  (Alvaro Herrera, )
 Re: strange performance regression between 7.4 and 8.1  (Ron, )
  Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
   Re: strange performance regression between 7.4 and 8.1  (Scott Marlowe, )
 Re: strange performance regression between 7.4 and 8.1  (Ron, )
  Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
 Re: strange performance regression between 7.4 and 8.1  (Anton Rommerskirchen, )
 Re: strange performance regression between 7.4 and 8.1  (Ron, )
  Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )
   Re: strange performance regression between 7.4 and 8.1  (Guido Neitzer, )
    Re: strange performance regression between 7.4 and 8.1  (Jeff Frost, )
     Re: strange performance regression between 7.4 and 8.1  ("Alex Deucher", )

On 02.03.2007, at 14:20, Alex Deucher wrote:

> Ah OK.  I see what you are saying;  thank you for clarifying.  Yes,
> the SAN is configured for maximum capacity; it has large RAID 5
> groups.  As I said earlier, we never intended to run a DB on the SAN,
> it just happened to come up, hence the configuration.

So why not dumping the stuff ones, importing into a PG configured to
use local discs (Or even ONE local disc, you might have the 16GB you
gave as a size for the db on the local machine, right?) and testing
whether the problem is with PG connecting to the SAN. So you have one
factor less to consider after all your changes.

Maybe it's just that something in the chain from PG to the actual HD
spindles kills your random access performance for getting the actual
rows.

cug


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