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From Jaepil Jeong <>
Subject Re: Auto Increament
Date Thu, 25 Mar 2010 12:57:43 GMT
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?
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?


On Thu, Mar 25, 2010 at 10:37 AM, Muhammed Nasrullah <>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:
> On Wed, Mar 24, 2010 at 9:57 PM, Jaepil Jeong <> 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


Everything arises, everything falls away.

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