code: function checkFieldInIndex(index, field) {
    var indexFields = index.def.fields.map(getKey);
    for (var i = 0, len = indexFields.length; i < len; i++) {
      var indexField = indexFields[i];
      if (field === indexField) {
        return true;
      }
    }
    return false;
  }
docs: couchdb second-lowest collation value