From: Josh Berkus <josh@agliodbs.com>
To: Kemin Zhou <kemin.zhou@ferring.com>
To: pgsql-sql@postgresql.org
Subject: Re: aggregate function stddev
Date: Thu, 9 Sep 2004 11:37:19 -0700
Message-ID: <200409091137.19204.josh@agliodbs.com> (raw)
In-Reply-To: <413F758A.80306@ferring.com>
References: <413F758A.80306@ferring.com>
Kemin,
> Just noticed that the postgres stddev is the stddev_sample formula.
> There are two different ways to calculate this value.
> Their difference is very small with large samle size. It would be nice
> to distinguish the two different versions.
Note sent to PGSQL-DOCS.
> I also noticed that oracle has stddev_sample and stddev_population.
> This is just a wish list.
Were you aware that in PostgreSQL you can write your own aggregates? It's
relatively easy to do.
--
Josh Berkus
Aglio Database Solutions
San Francisco
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To: pgsql-sql@postgresql.org
Cc: josh@agliodbs.com, kemin.zhou@ferring.com
Subject: Re: aggregate function stddev
In-Reply-To: <200409091137.19204.josh@agliodbs.com>
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