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From Keith Thomas <keith.tho...@gmail.com>
Subject Re: Possible to set the results' sort method?
Date Thu, 10 Sep 2009 02:52:42 GMT

I think I'm looking at the same problem with HBase as Dingding Ye. I need to
be able to retrieve a list of rows sorted by data in a column and I'm not
sure how to go about it without resorting to performing the sort on the
client which feels like I'm just giving up.

My current thinking is to create a map class that outputs key/value pairs
where the key is the field I want to sort upon and the value is row key.
This way I will get nice sorted input going into my reduce class. I guess I
would have to have once reduce class instance. 

However, I am unclear how I can return the row keys and the families with
their column data to the client from the reduce class. All the examples I
have found so far write the results to files/tables whereas I want to return
objects to a client. 

In the Hadoop Javadocs I notice a bunch of Comparators but as yet I've not
figure out their purpose. If I spend the cycles understanding the purpose of
these Comparators are they likely to be of help to me in formulating an
alternate/better approach to that described above?

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