You could implement WritableComparable
and create your own CompositeKey
with several fields, for example:
public static class CompositeKey implements WritableComparable<CompositeKey> {
public final Text site;
public final Text name;
public final LongWritable total;
public CompositeKey(Text site, Text name, LongWritable total) {
this.site = site;
this.name = name;
this.total = total;
}
@Override
public int compareTo(CompositeKey o) {
int siteCmp = site.compareTo(o.site);
if (siteCmp != 0) {
return siteCmp;
}
int nameCmp = name.compareTo(o.name);
if (nameCmp != 0) {
return nameCmp;
}
return total.compareTo(o.total);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CompositeKey that = (CompositeKey) o;
if (name != null ? !name.equals(that.name) : that.name != null) return false;
if (site != null ? !site.equals(that.site) : that.site != null) return false;
if (total != null ? !total.equals(that.total) : that.total != null) return false;
return true;
}
@Override
public int hashCode() {
int result = site != null ? site.hashCode() : 0;
result = 31 * result + (name != null ? name.hashCode() : 0);
result = 31 * result + (total != null ? total.hashCode() : 0);
return result;
}
@Override
public void write(DataOutput dataOutput) throws IOException {
site.write(dataOutput);
name.write(dataOutput);
total.write(dataOutput);
}
@Override
public void readFields(DataInput dataInput) throws IOException {
site.readFields(dataInput);
name.readFields(dataInput);
total.readFields(dataInput);
}
}