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From: Jens Alfke <jens@couchbase.com>
To: "user@couchdb.apache.org" <user@couchdb.apache.org>
Date: Fri, 15 Nov 2013 09:57:59 -0800
Subject: Re: decimal and builtin _sum function
Thread-Topic: decimal and builtin _sum function
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On Nov 15, 2013, at 9:31 AM, Mark Hahn <mark@reevuit.com> wrote:

>> When you store and then retrieve the number 0.3, you'd really like to kn=
ow
>> that it will come back in the same form. Without knowing about the innar=
ds
>> of CouchDb and how it processes JSON, that's hard to guarantee.
>=20
> A JS number is the same whether going through JSON or not.  There is no
> possible change.

That=92s not true. JavaScript usually stores numbers as 64-bit IEEE floatin=
g point. JSON is a _textual_ format, so converting numbers to JSON involves=
 writing them as strings, which is a lossy conversion. It=92s especially lo=
ssy if you sacrifice a bit of accuracy to display decimals in a more human-=
friendly way, i.e. writing =930.3=94 instead of =930.299999999998=94, which=
 I think most JSON encoders do because otherwise users complain about their=
 numbers coming out =93wrong=94 or at least =93too long=94.

=97Jens (who has written a few JSON encoders)=