private void updateFloatResult(int groupId, float yValue, Column xColumn, int xIndex) {
    if (!inits.get(groupId) || check(yValue, yFloatValues.get(groupId))) {
      inits.set(groupId, true);
      yFloatValues.set(groupId, yValue);
      updateX(groupId, xColumn, xIndex);
    }
  }
max(x,y) returns the value of x associated with the maximum value of y over all input values.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/source/relational/aggregation/grouped/GroupedMaxMinByBaseAccumulator.java