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Re: Help with performance problems

From: Ron St-Pierre <rstpierre(at)syscor(dot)com>
To: Chris Hoover <revoohc(at)sermonaudio(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Help with performance problems
Date: 2004-04-23 21:36:31
Message-ID: 40898C5F.7070004@syscor.com (view raw or flat)
Thread:
Lists: pgsql-performance
Chris Hoover wrote:

>On Friday 23 April 2004 14:57, Ron St-Pierre wrote:
>Does this apply to 7.3.4 also?
>
No it doesn't, I didn't look back through the thread far enough to see 
what you were running. I tried it on 7.3.4 and none of the summary info 
listed below was returned.  FWIW one of our DBs was slowing down 
considerably on an update (30+ minutes) and after I changed 
max_fsm_pages from the 7.4 default of 20,000 to 50,000, it completed in 
about eight minutes.

Ron

>  
>
>> Actually, since he's running 7.4, there's an even better way.  Do a
>> "VACUUM VERBOSE" (full-database vacuum --- doesn't matter whether you
>> ANALYZE or not).  At the end of the very voluminous output, you'll see
>> something like
>>
>>
>> INFO:  free space map: 240 relations, 490 pages stored; 4080 total pages
>>needed DETAIL:  Allocated FSM size: 1000 relations + 20000 pages = 178 kB
>>shared memory.
>>
>>
>> Here, I would need max_fsm_relations = 240 and max_fsm_pages = 4080 to
>> exactly cover the present freespace needs of my system.  I concur with
>> the suggestion to bump that up a good deal, of course, but that gives
>> you a real number to start from.
>>
>>
>> The DETAIL part of the message shows my current settings (which are the
>> defaults) and what the FSM is costing me in shared memory space.
>>
>>Good luck
>>Ron
>>
>>
>>
>>
>>---------------------------(end of broadcast)---------------------------
>>TIP 7: don't forget to increase your free space map settings
>>    
>>
>
>
>
>  
>



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Subject: Re: Setting Shared Buffers , Effective Cache, Sort Mem Parameters
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