Message-ID: <4B4879A0.2060703@zhukcity.ru>
Date: Sat, 09 Jan 2010 15:42:08 +0300
From: Nickolay <nitro@zhukcity.ru>
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To: =?UTF-8?B?R3J6ZWdvcnogSmHFm2tpZXdpY3o=?= <gryzman@gmail.com>
CC: pgsql-performance@postgresql.org
Subject: Re: PG optimization question
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	<2f4958ff1001090418i78dee992t5ff2d78a54187c07@mail.gmail.com>
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I do not see any way to normalize this table anymore. it's size is 4Gig 
for ~4M rows, i.e. 1Kb per row, i think it's ok.
Also there are 2 indexes: by date_time and by a couple of service fields 
(total index size is 250Mb now).
I think i'll be going to partition by months (approx. 1M rows or 1Gig 
per month), so it would be like 60 partitions for 5 years. Is that OK 
for postgres?
Oh, btw, 95% of queries are searching rows for current date (last 24 hours).
Also we use SELECT...FOR UPDATE row-level locking for updating the rows 
in archive (i.e. we INSERT new row when starting outgoing message 
transmittion and then doing SELECT...FOR UPDATE and UPDATE for source 
(incoming) message when outgoing message was sent), so I guess we would 
have to explicitly write the name of partition table (i.e. 
"archive_2009_12" instead of "archive") for SELECT...FOR UPDATE and 
UPDATE requests, as they may need to access row in previous partition 
instead of the current one.

Grzegorz Jaśkiewicz wrote:
> maybe that 'one big table' needs something called 'normalisation'
> first. See how much that will shed off. You might be surprised.
> The partitioning needs to be done by some constant intervals, of time
> - in your case. Whatever suits you, I would suggest to use the rate
> that will give you both ease of archiving/removal of old data (so not
> too wide), and also, one that would make sure that most of the data
> you'll be searching for in your queries will be in one , two
> partitions per query.
>
>
>