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From "Runping Qi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-531) Need to sort on more than the primary key
Date Fri, 15 Sep 2006 00:43:23 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-531?page=comments#action_12434863 ] 
            
Runping Qi commented on HADOOP-531:
-----------------------------------


Hadoop-531 captures a composite problem. To address problem, we need:

1. Allow different mappers for data from different input sources (HADOOP-372)
2. Allow to sort the map out data according to multiple keys (HADOOP-485)
3. Allow to clone reduce value iterators (HADOOP-475)




> Need to sort on more than the primary key
> -----------------------------------------
>
>                 Key: HADOOP-531
>                 URL: http://issues.apache.org/jira/browse/HADOOP-531
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: contrib/streaming
>    Affects Versions: 0.5.0
>            Reporter: Richard Kasperski
>
> There are many tasks where I need to have finer control over the ordering in the reduce
than a sort on a single key provides. Most of these situations arise when a merge two sources
of data and am attaching a single instance of one source to multiple instances of a second
source. I know that I can read all the the records with a single key. It's possible that there
might be many millions of these making memory demands that cannot be satisfied.

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