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https://issues.apache.org/jira/browse/MAPREDUCE-1126?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tom White updated MAPREDUCE-1126:
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Attachment: MAPREDUCE-1126.patch
Here's a much-simplified patch. To show how it works with nested types I've
added an example mapper with signature {{Mapper<LongWritable, Text, Utf8,
Map<Utf8, Long>>}} which uses the generic Avro serialization for the
intermediate key and value. It is configured by calling
{code}
Schema keySchema = Schema.create(Schema.Type.STRING);
Schema valSchema = Schema.parse("{\"type\":\"map\", \"values\":\"long\"}");
AvroGenericData.setMapOutputKeySchema(job, keySchema);
AvroGenericData.setMapOutputValueSchema(job, valSchema);
{code}
This replaces the calls to job.setMapOutputKeyClass() and
job.setMapOutputValueClass().
I'm interested in hearing people's thoughts about this.
> shuffle should use serialization to get comparator
> --------------------------------------------------
>
> Key: MAPREDUCE-1126
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1126
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: task
> Reporter: Doug Cutting
> Assignee: Aaron Kimball
> Fix For: 0.22.0
>
> Attachments: MAPREDUCE-1126.2.patch, MAPREDUCE-1126.3.patch,
> MAPREDUCE-1126.4.patch, MAPREDUCE-1126.5.patch, MAPREDUCE-1126.6.patch,
> MAPREDUCE-1126.patch, MAPREDUCE-1126.patch
>
>
> Currently the key comparator is defined as a Java class. Instead we should
> use the Serialization API to create key comparators. This would permit,
> e.g., Avro-based comparators to be used, permitting efficient sorting of
> complex data types without having to write a RawComparator in Java.
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