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From Artem Orobets <Artem.Orob...@exigenservices.com>
Subject RE: Are data migration tools for Cassandra exist?
Date Tue, 14 Jun 2011 10:44:06 GMT
Thank you for your answer.
We made investigation of Cassandra architecture, and we interested in approaches for solving
this problem.

From: aaron morton [mailto:aaron@thelastpickle.com]
Sent: Sunday, June 12, 2011 5:51 AM
To: user@cassandra.apache.org
Subject: Re: Are data migration tools for Cassandra exist?

Depends on your scale, you can either code something yourself through the API or take advantage
of the Hadoop integration and run jobs that read and write the data back. In either case you
can change the code first to write to the new column as well as the old, then update all existing
data, then change the code to read from the new field.

When you change the comparator the existing data is not migrated. Some changes are backwards
compatible, e.g. moving from BytesType to any other type, AsciiType to UTF8Type, moving from
LongType to IntegerType.

What sort of change did you want to do?

Hope that helps.

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 10 Jun 2011, at 21:21, Artem Orobets wrote:


If my application works in production and I change structure of my data (e.g. type of  column
name)
I will need to process all my stored data.
As variant I can create new column family and import legacy data.

I think, that is typical task, so tool for doing this should exist, but I can't find anything.
Are there any tools or proved approaches to solve this task ?


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