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Re: waiting for harddisk

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "petchimuthu lingam" <spmlingam(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: waiting for harddisk
Date: 2008-03-25 01:13:28
Message-ID: dcc563d10803241813g43cab94dtb3438b6df55ec533@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Mon, Mar 24, 2008 at 7:05 AM, petchimuthu lingam <spmlingam(at)gmail(dot)com> wrote:
> i am using postgresql 8.1.8,
>
> Following configurations:
>            shared_buffers = 5000
>             work_mem = 65536
>             maintenance_work_mem = 65536
>             effective_cache_size = 16000
>              random_page_cost = 0.1

That number, 0.1 is not logical.  anything below 1.0 is generally a
bad idea, and means that you've got some other setting wrong.

> The cpu is waiting percentage goes upto 50%, and query result comes later,
>
> i am using normal select query ( select * from table_name ).
>
> table has more then 6 million records.

You need faster disks if you want sequential scans to go faster.  Look
into a decent RAID controller (Areca, Escalade (forgot what they're
called now) or LSI) with battery backed cache.  Run RAID-10 on it with
as many drives as you can afford to throw at the problem.

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