From: Guy Rouillier <guyr-ml1@burntmail.com>
To: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: High update activity, PostgreSQL vs BigDBMS
Date: Sat, 06 Jan 2007 23:32:59 -0500
Message-ID: <45A077FB.3010802@burntmail.com> (raw)
In-Reply-To: <BB4FC28F-BDC1-424F-B330-EE9204404F1A@fastcrypt.com>
References: <45935A49.6080602@burntmail.com>
<bf54be870612280106n1247520dtb48e10cb4bdc43e9@mail.gmail.com>
<459F0EA6.30403@burntmail.com>
<BB4FC28F-BDC1-424F-B330-EE9204404F1A@fastcrypt.com>
Dave Cramer wrote:
>>
>> The box has 3 GB of memory. I would think that BigDBMS would be hurt
>> by this more than PG. Here are the settings I've modified in
>> postgresql.conf:
>
> As I said you need to set shared_buffers to at least 750MB this is the
> starting point, it can actually go higher. Additionally effective cache
> should be set to 2.25 G turning fsync is not a real world situation.
> Additional tuning of file systems can provide some gain, however as
> Craig pointed out some queries may need to be tweaked.
Dave, thanks for the hard numbers, I'll try them. I agree turning fsync
off is not a production option. In another reply to my original
posting, Alex mentioned that BigDBMS gets an advantage from its async
IO. So simply as a test, I turned fsync off in an attempt to open wide
all the pipes.
Regarding shared_buffers=750MB, the last discussions I remember on this
subject said that anything over 10,000 (8K buffers = 80 MB) had unproven
benefits. So I'm surprised to see such a large value suggested. I'll
certainly give it a try and see what happens.
>>
>> autovacuum=on
>> stats_row_level = on
>> max_connections = 10
>> listen_addresses = 'db01,localhost'
>> shared_buffers = 128MB
>> work_mem = 16MB
>> maintenance_work_mem = 64MB
>> temp_buffers = 32MB
>> max_fsm_pages = 204800
>> checkpoint_segments = 30
>> redirect_stderr = on
>> log_line_prefix = '%t %d'
--
Guy Rouillier
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To: pgsql-performance@postgresql.org
Cc: guyr-ml1@burntmail.com
Subject: Re: High update activity, PostgreSQL vs BigDBMS
In-Reply-To: <45A077FB.3010802@burntmail.com>
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