From: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
---|---|
To: | Graham Leggett <minfrin(at)sharp(dot)fm> |
Cc: | Christopher Browne <cbbrowne(at)acm(dot)org>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Money data type in PostgreSQL? |
Date: | 2003-12-06 04:03:47 |
Message-ID: | 3FD15523.9090400@Yahoo.com |
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Lists: | pgsql-general |
Graham Leggett wrote:
> Jan Wieck wrote:
>
>> You won't get any rounding errors in NUMERIC either. What people should
>> be concerned of is to find an arbitrary precision package for the
>> frontend programming language they're using.
>
> What is the definition of a numeric number? I understand (from studying
> numeric methods all those years ago) that the base 10 decimal number 0.1
> cannot be stored exactly in base 2 floating point, thus my use of
> integers - is numeric an arbitrary precision concept?
The PostgreSQL datatype NUMERIC is performing decimal arithmetic. The
original I wrote used to do it string based, with one digit per byte but
stored the number as some sort of BCD, one digit per nibble. Tom Lane
changed that a while back into base 10,000 storage and calculation,
which has the advantages of doing 4 digits per loop and no need to
convert back and forth between the storage and the computational
representation.
Jan
--
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