From: Jan Wieck <JanWieck@Yahoo.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Rajesh Kumar Mallah <mallah@trade-india.com>
Cc: Michael Glaesemann <grzm@myrealbox.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Arbitrary precision arithmatic with pgsql
Date: Tue, 31 Aug 2004 11:12:40 -0400
Message-ID: <41349568.6020400@Yahoo.com> (raw)
In-Reply-To: <29456.1093964692@sss.pgh.pa.us>
References: <41346727.8080901@trade-india.com>
<BD1D3E59-FB47-11D8-A2A0-000A95C88220@myrealbox.com>
<1089006C-FB4B-11D8-A2A0-000A95C88220@myrealbox.com>
<41347A0F.70300@trade-india.com>
<41348898.1070107@Yahoo.com>
<29456.1093964692@sss.pgh.pa.us>
On 8/31/2004 11:04 AM, Tom Lane wrote:
> Jan Wieck <JanWieck@Yahoo.com> writes:
>> I agree that doing
>> select 2::numeric ^ 100;
>> should emit some sort of a warning.
>
> I do not. The conversion of 2::numeric to float is exact, so AFAICS
> the only way to do that would be to make *every* coercion of numeric to
> float emit a warning. This is not a reasonable response to the fact
> that Rajesh is unaware of the set of available operators. Moreover
> it would essentially break float constants (since "2.0" starts life
> as numeric and is only cast to float when the context demands).
I thought they start life as an unknown literal ... that of course
changes things.
Jan
>
> I'd be in favor of adding a numeric^numeric operator to ease access to
> the existing pow() code, but I'm not sure this makes the issue go away
> entirely. It looks like "select 2 ^ 100" would still default to being
> a float operation.
>
> regression=# create operator ^ (procedure=pow, leftarg=numeric, rightarg=numeric);
> CREATE OPERATOR
> regression=# select 2::numeric ^ 100;
> ?column?
> --------------------------------------------------
> 1267650600228229401496703205376.0000000000000000
> (1 row)
>
> regression=# select 2 ^ 100;
> ?column?
> ----------------------
> 1.26765060022823e+30
> (1 row)
>
> regression=# select 2.0 ^ 100;
> ?column?
> --------------------------------------------------
> 1267650600228229401496703205376.0000000000000000
> (1 row)
>
>
> regards, tom lane
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck@Yahoo.com #
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To: pgsql-sql@postgresql.org
Cc: JanWieck@Yahoo.com, tgl@sss.pgh.pa.us, mallah@trade-india.com, grzm@myrealbox.com
Subject: Re: Arbitrary precision arithmatic with pgsql
In-Reply-To: <41349568.6020400@Yahoo.com>
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