code: @Override
      public Object[] scanRowKeys(final Table hTable, final Filter filter, final String columnFamilyName,
              final String columnName, final Class rowKeyClazz) throws IOException
      {
          List<Object> rowKeys = new ArrayList<Object>();
  
          if (scanner == null)
          {
              Scan s = new Scan();
              s.setFilter(filter);
              s.addColumn(Bytes.toBytes(columnFamilyName), Bytes.toBytes(columnName));
              scanner = hTable.getScanner(s);
              resultsIter = scanner.iterator();
          }
          if (fetchSize == null)
          {
              for (Result result : scanner)
              {
                  for (Cell cell : result.listCells())
                  {
                      rowKeys.add(HBaseUtils.fromBytes(CellUtil.cloneFamily(cell), rowKeyClazz));
                  }
              }
          }
          if (rowKeys != null && !rowKeys.isEmpty())
          {
              return rowKeys.toArray(new Object[0]);
          }
          return null;
      }
docs: /*
  (non-Javadoc)
  
  @see
  com.impetus.client.hbase.Reader#scanRowKeys(org.apache.hadoop.hbase.client
  .Table, org.apache.hadoop.hbase.filter.Filter, java.lang.String,
  java.lang.String, java.lang.Class)