Mailing-List: contact user-help@couchdb.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@couchdb.apache.org
Received-SPF: pass (athena.apache.org: domain of
 sebastiancohnen@googlemail.com designates 74.125.78.27 as permitted sender)
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=googlemail.com; s=gamma;
        h=content-type:mime-version:subject:from:in-reply-to:date
         :content-transfer-encoding:message-id:references:to:x-mailer;
        b=LUv+hnGrRSLDe62Y35N8fxbA011i3A16TN5jcXAuMLDLqnIxyD2C8dBdfrXV4wkWa2
         gpRPIIjw6pZUj+wk/545lWN4sjKbIzhBVhf9NDES8WWHZLZXnVAgWS7hM8MH5UlUeLSV
         P/nyZg8g9KAIByhpJKLCl1EnU9zNk7+71iPYU=
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Apple Message framework v1078)
Subject: Re: Short ids in url.
From: Sebastian Cohnen <sebastiancohnen@googlemail.com>
In-Reply-To: <z2sf39928a61004190548q1a3333e5z9d5fdd23e93ad1d0@mail.gmail.com>
Date: Mon, 19 Apr 2010 14:57:06 +0200
Content-Transfer-Encoding: quoted-printable
Message-Id: <7792D43A-DDDB-4289-9E85-57F4637C3AB2@googlemail.com>
References: <z2xf39928a61004190301rcc9efc86m1726f60c58607fba@mail.gmail.com>
 <n2lb5f7bf6c1004190316m8f9ba209z5b22e0132561096f@mail.gmail.com>
 <h2of39928a61004190319ud5e02646oc0986e0bae615c36@mail.gmail.com>
 <v2hb5f7bf6c1004190519jba2572d5xa5384494ae8da045@mail.gmail.com>
 <t2vf39928a61004190545la466cccj3ed02d7d8304ec95@mail.gmail.com>
 <z2sf39928a61004190548q1a3333e5z9d5fdd23e93ad1d0@mail.gmail.com>
To: user@couchdb.apache.org

no, UUIDs need to be as unique as possible. couchdb's _uuid API =
guarantees a high entropy for the produced IDs. the problem with (short) =
numeric IDs is, that they are more likely to produce collisions. if you =
do not use replication, you can basically do this:

1) create a number on your client
2) try to insert your document using this id
3) if you get a conflict, goto 1)
4) if your insert was successful, you are done.

the fundamental flaw to this approach is, that you more likely get =
conflicts when using replication (the shorter the IDs are, the more =
likely of course, see =
http://en.wikipedia.org/wiki/Birthday_attack#The_mathematics). =20


On 19.04.2010, at 14:48, faust 1111 wrote:

> is it possible send couch like /_uuids?count=3D10
> and its return me  short ids?
>=20
> 2010/4/19 faust 1111 <faust451@gmail.com>:
>> I need autogenerated short ids.
>> i try use rand(99999999) is it fine?
>>=20
>> 2010/4/19 David Coallier <david.coallier@gmail.com>:
>>> On 19 April 2010 11:19, faust 1111 <faust451@gmail.com> wrote:
>>>> yes i know that i can create my own ids
>>>> but i am interesting in what way couch guy's solve this.
>>>>=20
>>>=20
>>> Right... I'm not sure I exactly understand what you mean. Do you =
mean
>>> how could one do that from within CouchDB using autogenerated IDs or
>>> using something like "io" (http://github.com/janl/io) which is a =
short
>>> url generator using CouchDB :)
>>>=20
>>>=20
>>>=20
>>> --
>>> David Coallier
>>>=20
>>=20