TableMap's generic type inconsistcy with Hadoop
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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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