Message-ID: <47273DCF.4080600@clickware.de>
Date: Tue, 30 Oct 2007 15:21:03 +0100
From: Marc Schablewski <ms@clickware.de>
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CC: pgsql-performance@postgresql.org
Subject: Re: Optimizing PostgreSQL for Windows
References: <4727402E.90AD.0080.0@klinik.uni-regensburg.de>
In-Reply-To: <4727402E.90AD.0080.0@klinik.uni-regensburg.de>
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Although I'm not an expert on this stuff, but 32 MB of shared buffers
seems quite low to me, even for a windows machine. I'm running postgres
8.2 on my workstation with 2GB of ram and an AMD x64 3500+ with
shared_buffer set to 256MB without any trouble an it's running fine,
even on large datasets and other applications running. In my experience, 
shared_buffers are more important than work_mem. 

Have you tried increasing default_statistic_targets (eg to 200 or more) and after that
running "analyze" on your tables or the entire database?


Marc

Christian Rengstl wrote:
> Hi list,
>
> I have the following query:
> select t.a1, t.a2 from table1 t inner join table2 s 
> using(id) where t.pid='xyz' and s.chromosome=9 order by s.pos;
>
> With the following output from analyze:
> "Sort  (cost=35075.03..35077.51 rows=991 width=14) (actual
> time=33313.718..33321.935 rows=22599 loops=1)"
> "  Sort Key: s.pos"
> "  ->  Hash Join  (cost=7851.48..35025.71 rows=991 width=14) (actual
> time=256.513..33249.701 rows=22599 loops=1)"
> "        Hash Cond: ((t.id)::text = (s.id)::text)"
> "        ->  Bitmap Heap Scan on table1 t  (cost=388.25..27357.57
> rows=22286 width=23) (actual time=112.595..32989.663 rows=22864
> loops=1)"
> "              Recheck Cond: ((pid)::text = 'xyz'::text)"
> "              ->  Bitmap Index Scan on idx_table1  (cost=0.00..382.67
> rows=22286 width=0) (actual time=103.790..103.790 rows=22864 loops=1)"
> "                    Index Cond: ((pid)::text = 'xyz'::text)"
> "        ->  Hash  (cost=7180.62..7180.62 rows=22609 width=17) (actual
> time=143.867..143.867 rows=22864 loops=1)"
> "              ->  Bitmap Heap Scan on table2 s  (cost=333.00..7180.62
> rows=22609 width=17) (actual time=108.715..126.637 rows=22864 loops=1)"
> "                    Recheck Cond: ((chromosome)::text = '9'::text)"
> "                    ->  Bitmap Index Scan on idx_table2 
> (cost=0.00..327.35 rows=22609 width=0) (actual time=108.608..108.608
> rows=22864 loops=1)"
> "                          Index Cond: ((chromosome)::text =
> '9'::text)"
>
> My OS is Windows 2003 with 4GB Ram and Xeon Duo with 3.2 GHz;
> shared_buffers is set to 32MB (as I read it should be fairly low on
> Windows) and work_mem is set to 2500MB, but nevertheless the query takes
> about 38 seconds to finish. The table "table1" contains approx. 3
> million tuples and table2 approx. 500.000 tuples. If anyone could give
> an advice on either how to optimize the settings in postgresql.conf or
> anything else to make this query run faster, I really would appreciate.
>
>
>
>
> Christian Rengstl M.A.
> Klinik und Poliklinik für Innere Medizin II
> Kardiologie - Forschung
> Universitätsklinikum Regensburg
> B3 1.388
> Franz-Josef-Strauss-Allee 11
> 93053 Regensburg
> Tel.: +49-941-944-7230
>
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
>
>
>   

-- 

Marc Schablewski
click:ware Informationstechnik GmbH