James,

No, values do not come in any order for a given key. But it is achievable.

If you need them to be ordered, you need to perform a secondary sort operation, by using multiple key components.

See this 3-part series on how to do that, for example: http://www.cloudera.com/blog/2011/04/simple-moving-average-secondary-sort-and-mapreduce-part-3/
On 06-Dec-2011, at 6:25 AM, James Y. Li wrote:

Hi All,
I just begin to use Hadoop framework, and write my reduce() method. Wonder if the Iterable input values (associated with the input key) are already sorted. Thanks!

p.s. I am using the version 0.20.2-cdh3u1

-james

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