From: | PFC <lists(at)boutiquenumerique(dot)com> |
---|---|
To: | "Vanole, Mike" <Mike(dot)Vanole(at)cingular(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Calculating a moving average |
Date: | 2005-01-26 22:20:35 |
Message-ID: | opsk8dolimth1vuj@musicbox |
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Lists: | pgsql-general |
Make a plpgsql function which will iterate over the rows on which the
moving average is to be done (FOR row IN SELECT), of course use the
correct order, then use an array as a FIFO, add a row to the moving
average and push it, pop the old one and substract it.
Roundoff errors will bite your nether regions.
I spose the purpose of this is not to fetch the whole thing so that your
moving average will not have one result row per source row (or you'd do it
in the application), thus you can pre-shrink your dataset by putting some
avg() and group by in your source select.
> Hi,
> I need to calculate a moving average and I would like to do it with SQL,
> or a Pg function built for this purpose. I'm on Pg 7.4. Is this possible
> in Pg without a bunch of self joins, or is there a funtion available?
> Thanks,
> Mike
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