From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Josh Berkus <josh@agliodbs.com>
Cc: Kemin Zhou <kemin.zhou@ferring.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: aggregate function stddev
Date: Fri, 10 Sep 2004 17:48:30 -0400 (EDT)
Message-ID: <200409102148.i8ALmU129696@candle.pha.pa.us> (raw)
In-Reply-To: <200409091137.19204.josh@agliodbs.com>
Is this a TODO?
---------------------------------------------------------------------------
Josh Berkus wrote:
> 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
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
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To: pgsql-sql@postgresql.org
Cc: pgman@candle.pha.pa.us, josh@agliodbs.com, kemin.zhou@ferring.com
Subject: Re: aggregate function stddev
In-Reply-To: <200409102148.i8ALmU129696@candle.pha.pa.us>
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