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From: Thomas Kellerer <spam_eater@gmx.net>
To: pgsql-performance@postgresql.org
Subject: Re: Deterioration in performance when query executed in multi threads
Date: Mon, 06 May 2013 19:11:43 +0200
Message-ID: <km8o5u$l2t$1@ger.gmane.org> (raw)
In-Reply-To: <9A6B86D66BD3C2438AFACFA09354890F20A30B1B@EXCH01.sp.corp.collab.net>
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	<20130501162650.GI27807@aart.rice.edu>
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	<A76B25F2823E954C9E45E32FA49D70EC1B7C92E0@mail.corp.perceptron.com>
	<9A6B86D66BD3C2438AFACFA09354890F20A2F24A@EXCH01.sp.corp.collab.net>
	<A76B25F2823E954C9E45E32FA49D70EC1B7CAE91@mail.corp.perceptron.com>
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Anne Rosset, 06.05.2013 19:00:
> Postgres version: 9.0.13
>
>> Work_mem is set to 64MB
>> Shared_buffer to 240MB
>> Segment_size is 1GB
>> Wal_buffer is 10MB
>
> Artifact table: 251831 rows
> Field_value table: 77378 rows
> Mntr_subscription: 929071 rows
> Relationship: 270478 row
> Folder: 280356 rows
> Item: 716465 rows
> Sfuser: 5733 rows
> Project: 1817 rows
>
> 8CPUs
> RAM: 8GB
>

With 8GB RAM you should be able to increase shared_buffer to 1GB or maybe even higher especially if this is a dedicated server.
240MB is pretty conservative for a server with that amount of RAM (unless you have many other applications running on that box)

Also what are the values for

cpu_tuple_cost
seq_page_cost
random_page_cost
effective_cache_size

What kind of harddisk is in the server? SSD? Regular ones (spinning disks)?





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