One way to approach is emit |Integer.MAX_VALUE - your key ||as output of
mapper.|
Example
Mapper input
7 vim
2 emacs
9 firefox
Mapper output
(Integer.MAX_VALUE - 7) vim
(Integer.MAX_VALUE - 2) emacs
(Integer.MAX_VALUE - 9) firefox
If you need secondary sorting on second part, you have to use composite
key and write your own petitioner, comparator.
Regards,
Bhasker
On 11/06/2013 11:10, Pedro Sá da Costa wrote:
I created a MapReduce job example that that uses the sort mechanism of
hadoop to sort a file by the key in ascending order. This is an
example of the data:
7 vim
2 emacs
9 firefox
At the end, I get the result:
2 emacs
7 vim
9 firefox
Now I want to sort in reverse order, for the result be:
9 firefox
7 vim
2 emacs
How can I sort a file with pairs <Key Value> in reverse order?
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Best regards,
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Thanks & Regards,
Bhasker Allene
