docs: @Override
    public Deferred<byte[]> resolveTagkName(final TSDB tsdb) {
      final Config config = tsdb.getConfig();
      
      // resolve tag values if the filter is NOT case insensitive and there are 
      // fewer literals than the expansion limit
      if (!case_insensitive && 
          literals.size() <= config.getInt("tsd.query.filter.expansion_limit")) {
        return resolveTags(tsdb, literals);
      } else {
        return super.resolveTagkName(tsdb);
      }
    }