@Override
    public byte[] readVarchar() {
      String value = enforceMaxLength(
          convertToString(valuesReader.readDouble()));
      return convertToBytes(value);
    }
The reader who reads from the underlying double value value.

The data is read as double from the reader, then validated, converted and returned as per the
type defined in HMS.
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/vector/ParquetDataColumnReaderFactory.java