static int determineOperatorReservoirSize(int operatorParallelism, int numPartitions) {
    int coordinatorReservoirSize = determineCoordinatorReservoirSize(numPartitions);
    int totalOperatorSamples = coordinatorReservoirSize * OPERATOR_OVER_SAMPLE_RATIO;
    return (int) Math.ceil((double) totalOperatorSamples / operatorParallelism);
  }
@Test
  public void testOperatorReservoirSize() {
    assertThat(SketchUtil.determineOperatorReservoirSize(5, 3))
        .isEqualTo((10_002 * SketchUtil.OPERATOR_OVER_SAMPLE_RATIO) / 5);
    assertThat(SketchUtil.determineOperatorReservoirSize(123, 123))
        .isEqualTo((123_00 * SketchUtil.OPERATOR_OVER_SAMPLE_RATIO) / 123);
    assertThat(SketchUtil.determineOperatorReservoirSize(256, 123))
        .isEqualTo(
            (int) Math.ceil((double) (123_00 * SketchUtil.OPERATOR_OVER_SAMPLE_RATIO) / 256));
    assertThat(SketchUtil.determineOperatorReservoirSize(5_120, 10_123))
        .isEqualTo(
            (int) Math.ceil((double) (992_054 * SketchUtil.OPERATOR_OVER_SAMPLE_RATIO) / 5_120));
  }