public static HCatSchema getDataColumns(Configuration conf) throws IOException {
    InputJobInfo inputInfo = HCatUtil.getLastInputJobInfosFromConf(conf);
    Preconditions.checkNotNull(inputInfo,
        "inputJobInfo is null, setInput has not yet been called to save job into conf supplied.");
    return inputInfo.getTableInfo().getDataColumns();
  }
Return data columns for this input, can only be called after setInput is called,
since that takes care of adding a populated InputJobInfo object to its list in this job conf.
@return data columns of the table specified by the job.
@throws IOException
hcatalog/core/src/main/java/org/apache/hive/hcatalog/mapreduce/HCatInputFormat.java