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From "jaehong choi (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-1593) TableMap's generic type inconsistcy with Hadoop
Date Tue, 30 Jun 2009 16:42:47 GMT

     [ https://issues.apache.org/jira/browse/HBASE-1593?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

jaehong choi updated HBASE-1593:
--------------------------------

    Description: 
Hello~

I've been trying to global sort rows whose key is LongWritable and value is Text type.
Since there are a few result files after finishing a mapreduce job, I need to do a merge sort
on them. 

I want to sort rows in a decreasing order, but ImmutableBytesWritable only supports increasing
sort.
So, I assign LongWritable.DecreasingComparator on JobConf.setOutputKeyComparatorClass() in
order that output keys are in decreasing order.

However, There is a big problem. As you see, TableMap requires K must implement or extend
WritableComparable<K>, but LongWritable only implements WritableComparable, not WritableComparable<LongWritable>.
This makes a compilation time error.  

I think we should come up with an idea to solve this one. 

<code>
public interface TableMap<K extends WritableComparable<K>, V extends Writable>
extends Mapper<ImmutableBytesWritable, Result, K, V> {
}
<code>
<code>
public class LongWritable implements WritableComparable
<code>


  was:
Hello~

I've been trying to global sort rows whose key is LongWritable and value is Text type.
Since there are a few result files after finishing a mapreduce job, I need to do a merge sort
on them. 

I want to sort rows in a decreasing order, but ImmutableBytesWritable only supports increasing
sort.
So, I assign LongWritable.DecreasingComparator on JobConf.setOutputKeyComparatorClass() in
order that output keys are in decreasing order.

However, There is a big problem. As you see, TableMap requires K must implement or extend
WritableComparable<K>, but LongWritable only implements WritableComparable, not WritableComparable<LongWritable>.
This makes a compilation time error.  

I think we should come up with an idea to solve this one. 

<code>
public interface TableMap<K extends WritableComparable<K>, V extends Writable>
extends Mapper<ImmutableBytesWritable, Result, K, V> {
}
</code>
<code>
public class LongWritable implements WritableComparable
</code>



> TableMap's generic type inconsistcy with Hadoop
> -----------------------------------------------
>
>                 Key: HBASE-1593
>                 URL: https://issues.apache.org/jira/browse/HBASE-1593
>             Project: Hadoop HBase
>          Issue Type: Bug
>          Components: mapred
>            Reporter: jaehong choi
>
> Hello~
> I've been trying to global sort rows whose key is LongWritable and value is Text type.
> Since there are a few result files after finishing a mapreduce job, I need to do a merge
sort on them. 
> I want to sort rows in a decreasing order, but ImmutableBytesWritable only supports increasing
sort.
> So, I assign LongWritable.DecreasingComparator on JobConf.setOutputKeyComparatorClass()
in order that output keys are in decreasing order.
> However, There is a big problem. As you see, TableMap requires K must implement or extend
WritableComparable<K>, but LongWritable only implements WritableComparable, not WritableComparable<LongWritable>.
This makes a compilation time error.  
> I think we should come up with an idea to solve this one. 
> <code>
> public interface TableMap<K extends WritableComparable<K>, V extends Writable>
> extends Mapper<ImmutableBytesWritable, Result, K, V> {
> }
> <code>
> <code>
> public class LongWritable implements WritableComparable
> <code>

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