MomentSketchAggregatorFactory doesn't implement makeAggregateCombiner

[jjaen0823]

In 0.23.0, using a momentSketch aggregator at ingestion will result in the following exception during indexing merging:

2022-10-12T07:35:37,617 WARN [[index_parallel_newyork_momentsketch_test_agfjijan_2022-10-12T07:35:26.205Z]-appenderator-merge] org.apache.druid.segment.realtime.appenderator.AppenderatorImpl - Failed to push merged index for segment[newyork_momentsketch_test_2016-01-01T00:00:00.000Z_2016-02-01T00:00:00.000Z_2022-10-12T07:35:36.144Z].
org.apache.druid.java.util.common.UOE: [org.apache.druid.query.aggregation.momentsketch.aggregator.MomentSketchAggregatorFactory] does not implement makeAggregateCombiner()
    at org.apache.druid.query.aggregation.AggregatorFactory.makeAggregateCombiner(AggregatorFactory.java:128) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.query.aggregation.AggregatorFactory.makeNullableAggregateCombiner(AggregatorFactory.java:142) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.RowCombiningTimeAndDimsIterator.lambda$new$1(RowCombiningTimeAndDimsIterator.java:120) ~[druid-processing-0.23.0.jar:0.23.0]
    at java.util.Arrays.setAll(Arrays.java:4698) ~[?:1.8.0_275]
    at org.apache.druid.segment.RowCombiningTimeAndDimsIterator.<init>(RowCombiningTimeAndDimsIterator.java:120) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.lambda$merge$3(IndexMergerV9.java:1298) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.makeMergedTimeAndDimsIterator(IndexMergerV9.java:1360) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.makeIndexFiles(IndexMergerV9.java:293) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.merge(IndexMergerV9.java:1303) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.multiphaseMerge(IndexMergerV9.java:1120) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.IndexMergerV9.mergeQueryableIndex(IndexMergerV9.java:1062) ~[druid-processing-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.realtime.appenderator.AppenderatorImpl.mergeAndPush(AppenderatorImpl.java:923) ~[druid-server-0.23.0.jar:0.23.0]
    at org.apache.druid.segment.realtime.appenderator.AppenderatorImpl.lambda$push$1(AppenderatorImpl.java:784) ~[druid-server-0.23.0.jar:0.23.0]
    at com.google.common.util.concurrent.Futures$1.apply(Futures.java:713) [guava-16.0.1.jar:?]
    at com.google.common.util.concurrent.Futures$ChainingListenableFuture.run(Futures.java:861) [guava-16.0.1.jar:?]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_275]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_275]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_275]

It looks like the moment sketch aggregator doesn't have makeAggregateCombiner().

The ingestion spec:

...
          {
            "type": "momentSketch",
            "k": 3,
            "name": "ms_passenger_count_true",
            "fieldName": "passenger_count",
            "compress": true
          }
 ...

[abhishekagarwal87]

@jjaen0823 - it would seem that momentSketch is not with rollup-enabled ingestion. Happy to help you if you want to raise a PR to fix this gap.

[rohangarg]

@jjaen0823 : Incase you're not looking specifically for moment-sketch, you could also try DataSketches Quantiles Sketch aggregator (https://druid.apache.org/docs/latest/development/extensions-core/datasketches-quantiles.html) for quantiles over arbitrary data distributions with bounded errors (it also provides a bunch of other distribution summary functions).