code: function (sql, partition, params, partitioner) {
    this._sql = sql;
    this._partition = partition;
    this._name = partition + AttrRecs.NAME;
    this._params = this._toRec(params);
    this._partitioner = partitioner;
  }
docs: AttrRec should closely mimic the attrs table, e.g. the value of the attr is stored in JSON