Re: Seeking performance advice and explanation for high I/O on 8.3

From: Claus Guttesen <kometen(at)gmail(dot)com>
To: Scott Otis <scott(dot)otis(at)intand(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Seeking performance advice and explanation for high I/O on 8.3
Date: 2009-09-04 06:59:13
Message-ID: b41c75520909032359h51011320i88f423a1755d1278@mail.gmail.com
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>> > max_fsm_pages = 2800000
>> > max_fsm_relations = 160000
>
>> What does the last couple of lines from a 'vacuum analyze verbose'
>> say? I have max_fsm_pages = 4000000 and max_fsm_relations = 1500.
>
>> You can also try to lower random_page_cost to a lower value like 1.2
>> but I doubt this will help in your case.
>
> last couple lines from 'vacuumdb -a -v -z':
>
> INFO:  free space map contains 114754 pages in 42148 relations
> DETAIL:  A total of 734736 page slots are in use (including overhead).

----------------vvvvv-----------
> 734736 page slots are required to track all free space.
----------------^^^^^-----------

> Current limits are:  2800000 page slots, 160000 relations, using 26810 kB.

You can lower your max_fsm_pages setting to a number above 'xyz page
slots required ...' to 1000000 and fsm-relations to like 50000.

--
regards
Claus

When lenity and cruelty play for a kingdom,
the gentler gamester is the soonest winner.

Shakespeare

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