Re: Floating point type to store numbers

From: Andrew Sullivan <ajs(at)crankycanuck(dot)ca>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: Floating point type to store numbers
Date: 2007-04-17 20:53:18
Message-ID: 20070417205318.GC9094@phlogiston.dyndns.org
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On Tue, Apr 17, 2007 at 04:33:33PM -0400, Radhika Sambamurti wrote:
> Andrew,
> This has been quite helpful. My main concern is CPU cost. Thanks for the
> input.

You're welcome. Are you sure your main concern should be CPU cost?
It's true that numeric is more costly that float in a lot of cases,
but I know at least one auditor who will refuse to certify results
from programs that anywhere use floating-point storage or calculation
on accounting data. The problem is really that you can get compound
errors -- very small rounding errors several times can turn out to be
a big problem. (One quick primer that can help you understand this
is at <http://www2.hursley.ibm.com/decimal/decifaq1.html>.)

A
--
Andrew Sullivan | ajs(at)crankycanuck(dot)ca
The whole tendency of modern prose is away from concreteness.
--George Orwell

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