definition.getValueSizeEstimator());
key = new TupleEntry(definition.getGroupFields(), Tuple.size(definition.getGroupFields().size()));
input = new TupleEntry(definition.getInputFields(), Tuple.size(definition.getInputFields().size()));
keyFieldsPos = Lists.newArrayList();
inputFieldsPos = Lists.newArrayList();
this.serializationUtil = new TupleSerializationUtil(conf);
}