Also when I get rid of sum aggregation it works perfectly. (Is this a valid sql?)

SELECT "timestamp",variant_id FROM Sales WHERE operator_id = 1 AND campaign_id = 1 GROUP BY Hour("timestamp"), variant_id

SelecT Hour(“timestamp”) not “timestamp”

When I do that I get

{
  "message": "QueryExecutionError:\norg.apache.pinot.core.query.exception.BadQueryRequestException: Unsupported function: other with 1 parameters\n\tat org.apache.pinot.core.operator.transform.function.TransformFunctionFactory.get(TransformFunctionFactory.java:181)\n\tat org.apache.pinot.core.operator.transform.TransformOperator.<init>(TransformOperator.java:56)\n\tat org.apache.pinot.core.plan.TransformPlanNode.run(TransformPlanNode.java:52)\n\tat org.apache.pinot.core.plan.AggregationPlanNode.run(AggregationPlanNode.java:97)\n\tat org.apache.pinot.core.plan.AggregationPlanNode.run(AggregationPlanNode.java:40)\n\tat org.apache.pinot.core.plan.CombinePlanNode.run(CombinePlanNode.java:89)\n\tat org.apache.pinot.core.plan.InstanceResponsePlanNode.run(InstanceResponsePlanNode.java:33)\n\tat org.apache.pinot.core.plan.GlobalPlanImplV0.execute(GlobalPlanImplV0.java:45)\n\tat org.apache.pinot.core.query.executor.ServerQueryExecutorV1Impl.processQuery(ServerQueryExecutorV1Impl.java:221)\n\tat org.apache.pinot.core.query.scheduler.QueryScheduler.processQueryAndSerialize(QueryScheduler.java:155)\n\tat org.apache.pinot.core.query.scheduler.QueryScheduler.lambda$createQueryFutureTask$0(QueryScheduler.java:139)\n\tat java.util.concurrent.FutureTask.run(FutureTask.java:266)\n\tat java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)\n\tat shaded.com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111)",
  "errorCode": 200
}

can you try query like :

SELECT Hour("timestamp"),variant_id,sum(amount) FROM Sales WHERE operator_id = 1 AND campaign_id = 1 GROUP BY Hour("timestamp"), variant_id

I just tried and got the following error again.

[
  {
    "message": "QueryExecutionError:\norg.apache.pinot.core.query.exception.BadQueryRequestException: Unsupported function: other with 1 parameters\n\tat org.apache.pinot.core.operator.transform.function.TransformFunctionFactory.get(TransformFunctionFactory.java:181)\n\tat org.apache.pinot.core.operator.transform.TransformOperator.<init>(TransformOperator.java:56)\n\tat org.apache.pinot.core.plan.TransformPlanNode.run(TransformPlanNode.java:52)\n\tat org.apache.pinot.core.plan.AggregationGroupByOrderByPlanNode.run(AggregationGroupByOrderByPlanNode.java:108)\n\tat org.apache.pinot.core.plan.AggregationGroupByOrderByPlanNode.run(AggregationGroupByOrderByPlanNode.java:40)\n\tat org.apache.pinot.core.plan.CombinePlanNode.run(CombinePlanNode.java:89)\n\tat org.apache.pinot.core.plan.InstanceResponsePlanNode.run(InstanceResponsePlanNode.java:33)\n\tat org.apache.pinot.core.plan.GlobalPlanImplV0.execute(GlobalPlanImplV0.java:45)\n\tat org.apache.pinot.core.query.executor.ServerQueryExecutorV1Impl.processQuery(ServerQueryExecutorV1Impl.java:221)\n\tat org.apache.pinot.core.query.scheduler.QueryScheduler.processQueryAndSerialize(QueryScheduler.java:155)\n\tat org.apache.pinot.core.query.scheduler.QueryScheduler.lambda$createQueryFutureTask$0(QueryScheduler.java:139)\n\tat java.util.concurrent.FutureTask.run(FutureTask.java:266)\n\tat java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)\n\tat shaded.com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111)",
    "errorCode": 200
  }
]

which pinot version you are running ?

this one. It's pretty much the latest. https://hub.docker.com/layers/apachepinot/pinot/latest/images/sha256-b733dadb0f50b81d4031d86ceff5b2ef8dcf56ebcdc6fc10937fa28efb0c0fcc?context=explore

There is a bug for function name parsing, I will fix it and publish a new docker image.

@Xiang Fu I tried with

sha256:32e77501b4120211e7c4d16b8afcb6fe5c46aec853bcb2e413cc86c35b093fc7

and still getting the same error.

Cool!