private void updateFloatResult(long time, float yValue, Column xColumn, int xIndex) {
    if (!initResult
        || check(yValue, yExtremeValue.getFloat())
        || (yValue == yExtremeValue.getFloat() && time < yTimeStamp)) {
      initResult = true;
      yTimeStamp = time;
      yExtremeValue.setFloat(yValue);
      updateX(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/aggregation/MaxMinByBaseAccumulator.java