@Override
  public long ramBytesUsed() {
    return INSTANCE_SIZE
        + children.stream()
            .mapToLong(MemoryEstimationHelper::getEstimatedSizeOfAccountableObject)
            .sum()
        + MemoryEstimationHelper.getEstimatedSizeOfAccountableObject(operatorContext)
        + RamUsageEstimator.sizeOf(canCallNext)
        + resultTsBlockBuilder.getRetainedSizeInBytes();
  }
{@link AggregationOperator} can process the situation: aggregation of intermediate aggregate
result, it will output one tsBlock contain many results on aggregation time intervals. One
intermediate tsBlock input will contain the result of many time intervals.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/process/AggregationOperator.java