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From: Carlo Stonebanks <stonec.register@sympatico.ca>
To: pgsql-performance@postgresql.org
Subject: Re: Massive table (500M rows) update nightmare
Date: Fri, 8 Jan 2010 12:06:14 -0500
Message-ID: <hi7okp$2kca$1@news.hub.org> (raw)
In-Reply-To: <dcc563d11001072221g66d3db9cr3556d49b2bdee47e@mail.gmail.com>
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	<dcc563d11001071740q572cdae2re410788fe790dbf6@mail.gmail.com>
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	<dcc563d11001072221g66d3db9cr3556d49b2bdee47e@mail.gmail.com>

> crank it up more and delay the checkpoints as much as possible during
> these updates.  64 segments is already 1024M.

We have 425M rows, total table size is 78GB, so we can imagine a worst case 
UPDATE write is less than 200 bytes * number of rows specified in the update 
(is that logic correct?).

Inerestingly, the total index size is 148GB, twice that of the table, which 
may be an indication of where the performance bottleneck is.

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