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Posted to mapreduce-dev@hadoop.apache.org by "Aaron Kimball (JIRA)" <ji...@apache.org> on 2009/11/28 01:43:20 UTC
[jira] Resolved: (MAPREDUCE-1216) MRUnit Should Sort Reduce Input
[ https://issues.apache.org/jira/browse/MAPREDUCE-1216?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Aaron Kimball resolved MAPREDUCE-1216.
--------------------------------------
Resolution: Invalid
> MRUnit Should Sort Reduce Input
> -------------------------------
>
> Key: MAPREDUCE-1216
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1216
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 0.20.1
> Environment: Cloudera Distribution for Hadoop 0.20.1 + 133
> Reporter: Ed Kohlwey
> Original Estimate: 3h
> Remaining Estimate: 3h
>
> MRUnit should sort the input for a reduce task, the same way hadoop does.
> This is useful if you have a reduce task that, for instance, removes duplicate key value pairs.
> example:
> {code:java}
> class BadReducer extends Reducer{
> public void reduce(...){
> Text last = new Text();
> for(Text text: values){
> if(!text.equals(last)){
> context.write(key, text);
> last.set(text);
> }
> }
> }
> }
> {code}
> {code:java}
> ReduceDriver driver = new ReduceDriver()
> driver.setInputKey("foo");
> driver.addInputValue("bar");
> driver.addInputValue("bar");
> driver.addInputValue("foo");
> {code}
> produces different results than
> {code:java}
> ReduceDriver driver = new ReduceDriver()
> driver.setInputKey("foo");
> driver.addInputValue("bar");
> driver.addInputValue("foo");
> driver.addInputValue("bar");
> {code}
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