[FLINK-31239][hive] Fix native sum function can't get the corrected value when the argument type is string

[lsyldliu]

What is the purpose of the change

Currently, for the following case:

tableEnv.executeSql("create table test_sum_dec(a int, x string, z decimal(10, 5))");
tableEnv.executeSql(
                "insert into test_sum_dec values (1, 'b', null), "
                        + "(1, 'b', 1.2), "
                        + "(2, 'b', null), "
                        + "(2, 'b', null),"
                        + "(4, '1', null),"
                        + "(4, 'b', null)")
        .await();

List<Row> result =
        CollectionUtil.iteratorToList(
                tableEnv.executeSql("select a, sum(x) from test_sum_dec group by a")
                        .collect());
assertThat(result.toString()).isEqualTo("[+I[1,null], +I[2, null], +I[4, 1.0]]");

The native sum function return [+I[1,null], +I[2, null], +I[4, 1.0]], but hive sum function return [+I[1,0.0], +I[2,0.0], +I[4, 1.0]]. The native function return result is not consistent with hive, this is a bug, so we should fix it.

Brief change log

• Fix native sum function can't get the corrected value when the argument type is string
• Add some notes in document about table.exec.hive.native-agg-function.enabled option can't turned on per job when using it via SqlClient

Verifying this change

This change added tests and can be verified as follows:

• Added integration tests in HiveDialectAggITCase

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (yes)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: ( no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicabled)

[flinkbot]

CI report:

• a596e57 Azure: SUCCESS

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[godfreyhe]

Thanks for the contribution, I left some comments

[godfreyhe]

I think we do not need add the issue number in the doc.

[godfreyhe]

what's the hive behavior when input is empty?

btw, please add a test to cover this case

[lsyldliu]

Hive code as following:

@AggregationType(estimable = true)
    static class SumLongAgg extends SumAgg<Long> {
      @Override
      public int estimate() { return JavaDataModel.PRIMITIVES1 + JavaDataModel.PRIMITIVES2; }
    }

    @Override
    public AggregationBuffer getNewAggregationBuffer() throws HiveException {
      SumLongAgg result = new SumLongAgg();
      reset(result);
      return result;
    }

    @Override
    public void reset(AggregationBuffer agg) throws HiveException {
      SumLongAgg myagg = (SumLongAgg) agg;
      myagg.empty = true;
      myagg.sum = 0L;
      myagg.uniqueObjects = new HashSet<ObjectInspectorObject>();
    }

    private boolean warned = false;

    @Override
    public void iterate(AggregationBuffer agg, Object[] parameters) throws HiveException {
      assert (parameters.length == 1);
      try {
        if (isEligibleValue((SumLongAgg) agg, parameters[0])) {
          ((SumLongAgg)agg).empty = false;
          ((SumLongAgg)agg).sum += PrimitiveObjectInspectorUtils.getLong(parameters[0], inputOI);
        }
      } catch (NumberFormatException e) {
        if (!warned) {
          warned = true;
          LOG.warn(getClass().getSimpleName() + " "
              + StringUtils.stringifyException(e));
        }
      }
    }

    @Override
    public void merge(AggregationBuffer agg, Object partial) throws HiveException {
      if (partial != null) {
        SumLongAgg myagg = (SumLongAgg) agg;
        myagg.empty = false;
        if (isWindowingDistinct()) {
          throw new HiveException("Distinct windowing UDAF doesn't support merge and terminatePartial");
        } else {
            myagg.sum += PrimitiveObjectInspectorUtils.getLong(partial, inputOI);
        }
      }
    }

    @Override
    public Object terminate(AggregationBuffer agg) throws HiveException {
      SumLongAgg myagg = (SumLongAgg) agg;
      if (myagg.empty) {
        return null;
      }
      result.set(myagg.sum);
      return result;
    }

It returns a null value if all elements are null.

[lsyldliu]

@godfreyhe Thanks for your reviewing, I've addressed your comments. Could you help retain two commits when you merge?

[godfreyhe]

LGTM