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taking a sparse slice of an array

From: Michael Lush <mjlush(at)gmail(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Subject: taking a sparse slice of an array
Date: 2011-12-09 08:15:17
Message-ID: CACXX7Mcqa9ONiYi=Msjn81FmrqTro52j1KqA6cqHkdVPCKq3yw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-novice
Thank you for the useful responses to 'Big Wide Datasets'

I decided to have a go with the array option and initially it looked very
promising

time psql test -c "SELECT sample_id, snp_data[40000] FROM gwas_test" >
/dev/null

returned in 5 minutes from a 100000 row table.

The trouble is that it does not scale

time psql test -c "SELECT sample_id, snp_data[40000], snp_data[50000] FROM
gwas_test" > /dev/null

takes 10 minutes :-(

Is there anyway to speed this up I can see snp_data[40000:50000] returns
values from 40 to 50 thousand,
is there any way to so something like

snp_data[1,55,1000,40000,50000]

which would just return a 5 element array?

--
Michael

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Next:From: Jean-Yves F. BarbierDate: 2011-12-09 08:33:31
Subject: Re: taking a sparse slice of an array
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