code: protected String generateSelectByShardCql(EnumSet<?> columns, Integer shardNum) {
          StringBuilder sb = new StringBuilder()
              .append("SELECT ");
          boolean first = true;
          for (Enum<?> column : columns) {
              if (first) {
                  first = false;
              } else {
                  sb.append(",");
              }
              sb.append(column.name());
          }
          sb.append("\n")
              .append("FROM ").append(cassandra.getColumnFamily())
              .append("\n").append("WHERE ").append(Columns.shard_num.name())
              .append(" = ").append(shardNum).append("\n");
          return sb.toString();
      }
docs: Generate the CQL to select specific columns by shard number.
  <pre>
  SELECT ${columns}... FROM script_repo WHERE shard_num = ?
  </pre>