@Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    if (!super.equals(o)) {
      return false;
    }
    AggregationNode that = (AggregationNode) o;
    return Objects.equals(aggregations, that.aggregations)
        && Objects.equals(groupingSets, that.groupingSets)
        && Objects.equals(step, that.step)
        && Objects.equals(hashSymbol, that.hashSymbol)
        && Objects.equals(groupIdSymbol, that.groupIdSymbol);
  }
@return whether this node should produce default output in case of no input pages. For example
    for query:
    <p>SELECT count(*) FROM nation WHERE nationkey < 0
    <p>A default output of "0" is expected to be produced by FINAL aggregation operator.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/node/AggregationNode.java