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From Maysam Yabandeh <may...@yahoo-inc.com>
Subject Re: Hbase Transactional support
Date Mon, 19 Mar 2012 18:44:34 GMT
Hi Deepika,

Omid provides Snapshot Isolation (SI), which is a well-known isolation guarantee in database
systems such as Oracle. In short, each transaction reads from a consistent snapshot that does
not include partial changes by concurrent (or failed) transactions. SI also prevents write-write
conflicts between concurrent transactions. The overhead of Omid on HBase is negligible and
does not require any changes into HBase, with the only exception of HBase garbage collection
algorithm that is replaced via a coprocessor. hbase-trx, on the other hand, does not provide
read snapshots and is not safe with client failures. You can find a more detailed comparison
in the Omid wiki page:

- Maysam Yabandeh

On Mar 19, 2012, at 6:49 PM, Deepika Khera wrote:

> Hi,
> I have some map reduce jobs that write to Hbase. I am trying to pick a
> library that could provide transactional support for Hbase. I looked at
> Omid and hbase-trx .
> Could you please provide me with a comparison between the two so I can
> make the right choice. 
> Are there any other ways to do this?
> Thanks,
> Deepika

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