'Retrieve some values for the given column'

def values_for_column(self, column_name, limit=10000):

    if self.fetch_values_from:
        from_dttm = utils.parse_human_datetime(self.fetch_values_from)
    else:
        from_dttm = datetime(1970, 1, 1)
    qry = dict(datasource=self.datasource_name, granularity='all', intervals=((from_dttm.isoformat() + '/') + datetime.now().isoformat()), aggregations=dict(count=count('count')), dimension=column_name, metric='count', threshold=limit)
    client = self.cluster.get_pydruid_client()
    client.topn(**qry)
    df = client.export_pandas()
    return [row[column_name] for row in df.to_records(index=False)]
