Question about hash of BucketInteger

[xicm]

Query engine

No response

Question

  private static class BucketInteger extends Bucket<Integer>
      implements SerializableFunction<Integer, Integer> {

    private BucketInteger(int numBuckets) {
      super(numBuckets);
    }

    @Override
    protected int hash(Integer value) {
      return BucketUtil.hash(value);
    }
  }

Why do we use Murmur3 instead of the int value itself?

test code

Bucket bucket = Bucket.get(Types.IntegerType.get(), 10);
        List<Integer> list = new ArrayList<>();
        List<Integer> randomList = new ArrayList<>();

        Random rand = new Random();

        for (int i = 0; i < 10000000; i++) {
            int num = rand.nextInt(10000);
            randomList.add(bucket.apply(num));
            list.add(bucket.apply(i));
        }

        System.out.println("natural  list");
        list.stream()
                .collect(Collectors.groupingBy(item -> item, Collectors.counting()))
                .forEach((key, value) -> System.out.println(key + ": " + value));

        System.out.println("random list");
        randomList.stream()
                .collect(Collectors.groupingBy(item -> item, Collectors.counting()))
                .forEach((key, value) -> System.out.println(key + ": " + value));

result with Murmur3

natural  list
0: 1000996
1: 999922
2: 1000005
3: 1000139
4: 1001529
5: 998785
6: 999291
7: 999777
8: 999204
9: 1000352
random list
0: 998404
1: 1005602
2: 1021090
3: 1021668
4: 996615
5: 1046078
6: 1023192
7: 997321
8: 923906
9: 966124

result of the origin value

natural  list
0: 1000000
1: 1000000
2: 1000000
3: 1000000
4: 1000000
5: 1000000
6: 1000000
7: 1000000
8: 1000000
9: 1000000
random list
0: 1001911
1: 997982
2: 999024
3: 1000518
4: 999166
5: 999954
6: 1001863
7: 1000033
8: 997981
9: 1001568