@Override
 public int hashCode() {
   final int prime = 31;
   int result = super.hashCode();
   result = prime * result + ((accessor == null) ? 0 : accessor.hashCode());
   return result;
 }
 @Override
 public void readFields(DataInput input) throws IOException {
   super.readFields(input);
   accessor = new RowKeyValueAccessor();
   accessor.readFields(input);
   fromType = type; // fromType only needed on client side
 }
 @Override
 public boolean equals(Object obj) {
   if (this == obj) return true;
   if (!super.equals(obj)) return false;
   if (getClass() != obj.getClass()) return false;
   RowKeyColumnExpression other = (RowKeyColumnExpression) obj;
   return accessor.equals(other.accessor);
 }
 @Override
 public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
   tuple.getKey(ptr);
   int offset = accessor.getOffset(ptr.get(), ptr.getOffset());
   // Null is represented in the last expression of a multi-part key
   // by the bytes not being present.
   int maxOffset = ptr.getOffset() + ptr.getLength();
   if (offset < maxOffset) {
     byte[] buffer = ptr.get();
     int fixedByteSize = -1;
     // FIXME: fixedByteSize <= maxByteSize ? fixedByteSize : 0 required because HBase passes bogus
     // keys to filter to position scan (HBASE-6562)
     if (fromType.isFixedWidth()) {
       fixedByteSize = getByteSize();
       fixedByteSize = fixedByteSize <= maxOffset ? fixedByteSize : 0;
     }
     int length =
         fixedByteSize >= 0 ? fixedByteSize : accessor.getLength(buffer, offset, maxOffset);
     // In the middle of the key, an empty variable length byte array represents null
     if (length > 0) {
       /*
       if (type == fromType) {
           ptr.set(buffer,offset,length);
       } else {
           ptr.set(type.toBytes(type.toObject(buffer, offset, length, fromType)));
       }
       */
       ptr.set(buffer, offset, length);
       type.coerceBytes(ptr, fromType, getSortOrder(), getSortOrder());
     } else {
       ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
     }
     return true;
   }
   return false;
 }
 @Override
 public String toString() {
   return name == null ? "PK[" + accessor.getIndex() + "]" : name;
 }
 public int getPosition() {
   return accessor.getIndex();
 }
 @Override
 public void write(DataOutput output) throws IOException {
   super.write(output);
   accessor.write(output);
 }