From: Tom Lane <tgl@sss.pgh.pa.us>
To: George Pavlov <gpavlov@mynewplace.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: avg() with floating-point types
Date: Sun, 01 Jan 2006 20:25:50 -0500
Message-ID: <26697.1136165150@sss.pgh.pa.us> (raw)
In-Reply-To: <CCB89282FCE1024EA3DCE687A96A516403AB93C2@ehost010-6.exch010.intermedia.net>
References: <CCB89282FCE1024EA3DCE687A96A516403AB93C2@ehost010-6.exch010.intermedia.net>
"George Pavlov" <gpavlov@mynewplace.com> writes:
> The datatype of both city.latitude and postal_code.latitude is
> number(16,12).
> This works, but I would like to understand why there is sometimes a
> discrepancy between avg(pc.latitude) and what actually gets inserted
> into the city table -- is it the usual floating-point discrepancy or is
> there something I can do about it? E.g. after the above update:
You're forcing the result of the avg() calculation to be rounded to 12
digits when you store it into city.latitude. Your example simply shows
that the avg() calculation is being done to more precision than that.
regards, tom lane
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, gpavlov@mynewplace.com
Subject: Re: avg() with floating-point types
In-Reply-To: <26697.1136165150@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox