@Override
  public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
      throws Exception {
    configurations
        .setAccessStrategy(new SlidingSizeWindowAccessStrategy(Integer.MAX_VALUE))
        .setOutputDataType(parameters.getDataType(0));
    method = parameters.getStringOrDefault("method", "linear");
  }
This function is used to interpolate time series.
library-udf/src/main/java/org/apache/iotdb/library/drepair/UDTFValueFill.java