Major Description
We should add a Pair<K,V> class, implementing SpecificRecord, that combines instances of two schemas (specific or generic). Pairs would be compared by key, ignoring value. The template for its schema would be:
{"type": "record", "name": "org.apache.avro.mapred.Pair", "fields":[
{"name": "key", "type":" <<insert key schema here>>},
{"name": "value", "order": "ignore", "type": <<insert value schema>>}
]}
When map outputs are instances of this class, a reducer may be used whose reduce method is something like:
public abstract void reduce(K key, Iterable<V> values);