From: Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
To: pgsql-sql@postgresql.org
Subject: Re: graphing time series data
Date: Wed, 14 Apr 2010 18:11:53 +0200
Message-ID: <20100414161152.GA17805@apartia.fr> (raw)
In-Reply-To: <n2i162867791004140906l3cf1ac73q39343c54bb5facb1@mail.gmail.com>
References: <20100414145434.GA13682@apartia.fr>
<r2k396486431004140846y4579154erc604d6286ac2cb89@mail.gmail.com>
<20100414154958.GA16847@apartia.fr>
<n2i162867791004140906l3cf1ac73q39343c54bb5facb1@mail.gmail.com>
On Wed, Apr 14, 2010 at 06:06:59PM +0200, Pavel Stehule wrote:
> I don't understand well. Why you don't use a function date_trunc(),
>
> select date_trunc('week', created), count(*)
> from price
> group by date_trunc('week', created)
Because if a price doesn't change for more than a week, then some weeks
will have bad statistical distribution (i.e not including prices which
only have their 'modified' updated). So I (think I) need to (1) generate
the weeks separately and (2) average prices that are current for each
week.
But I could be missing something obvious.
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To: pgsql-sql@postgresql.org
Cc: vindex+lists-pgsql-sql@apartia.org
Subject: Re: graphing time series data
In-Reply-To: <20100414161152.GA17805@apartia.fr>
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