incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ryan King <r...@twitter.com>
Subject Re: Auto Increament
Date Thu, 25 Mar 2010 23:16:31 GMT
On Thu, Mar 25, 2010 at 5:57 AM, Jaepil Jeong <zgdr7th@gmail.com> wrote:
> Hi there,
> Thanks to all for reply. But I still have a question:
> 1. When I using Twtiter via Tweetie which is iPhone application, I can see
> the unique ID for each of users in their personal profile page. It seems
> like incremental number. As far as I know, Twitter using Cassandra for its
> back-end. My question is how do they do that?

It is true that we're currently using auto-increment to produce the id
numbers for tweets. That will soon change, though (more about that
later).

-ryan

> 2. I know UUID is the best solution to generate unique ID. However, I worry
> about value conflicts with billions of columns. Is there anyone who has
> experience about this?
> Thanks,
>
>
> On Thu, Mar 25, 2010 at 10:37 AM, Muhammed Nasrullah <nasrullah@gmail.com>
> wrote:
>>
>> You replace it with an UUID. In a true scalable distributed system, you
>> should not have an auto_increment. If you are writing to 10
>> nodes simultaneously, it becomes near impossible to keep a single
>> incrementing value being used by the entire system without causing a lot of
>> write contention.
>> This is how you generate a Time-UUID in
>> Java: http://wiki.apache.org/cassandra/FAQ#working_with_timeuuid_in_java
>>
>> On Wed, Mar 24, 2010 at 9:57 PM, Jaepil Jeong <zgdr7th@gmail.com> wrote:
>>>
>>> Hi there,
>>>
>>> I just started research about Cassandra to replace MySQL, and I have a
>>> question: How can I replace the "auto increament" attribute in MySQL
>>> with Cassandra? If I can't, how can I generate an ID which is globally
>>> unique for each of columns?
>>>
>>> Thanks,
>>>
>>> Sent from my iPhone
>>
>
>
>
> --
> Jaepil Jeong
> Software Architect
>
> twitter: http://twitter.com/JaepilJeong
> msn: zgdr7th@hotmail.com
>
> Everything arises, everything falls away.
>
>

Mime
View raw message