Horton

Re: Exponentiation confusion

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Erik Wienhold <ewie@ewie.name>, Adrian Klaver <adrian.klaver@aklaver.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-10-18T19:18:28Z
Lists: pgsql-hackers, pgsql-general 
On Tue, Oct 18, 2022 at 6:18 AM Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
> Overall, I'm quite happy with these results. The question is, should
> this be back-patched?
>
> In the past, I think I've only back-patched numeric bug-fixes where
> the digits output by the old code were incorrect or an error was
> thrown, not changes that resulted in a different number of digits
> being output, changing the precision of already-correct results.
> However, having 10.0^(-18) produce zero seems pretty bad, so my
> inclination is to back-patch, unless anyone objects.

I don't think that back-patching is a very good idea. The bar for
changing query results should be super-high. Applications can depend
on the existing behavior even if it's wrong.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

  1. Improve the accuracy of numeric power() for integer exponents.