Re: Help with performance problems

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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