Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3472#discussion_r104282353
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/dataset/DataSetAggregate.scala
---
@@ -87,47 +89,67 @@ class DataSetAggregate(
override def translateToPlan(tableEnv: BatchTableEnvironment):
DataSet[Row] = {
- val groupingKeys = grouping.indices.toArray
-
- val mapFunction = AggregateUtil.createPrepareMapFunction(
- namedAggregates,
- grouping,
- inputType)
-
- val groupReduceFunction =
AggregateUtil.createAggregateGroupReduceFunction(
- namedAggregates,
- inputType,
- rowRelDataType,
- grouping,
- inGroupingSet)
+ val (preAgg: Option[DataSetPreAggFunction],
+ preAggType: Option[TypeInformation[Row]],
+ finalAgg: GroupReduceFunction[Row, Row]) =
+ AggregateUtil.createDataSetAggregateFunctions(
+ namedAggregates,
+ inputType,
+ rowRelDataType,
+ grouping,
+ inGroupingSet)
val inputDS =
getInput.asInstanceOf[DataSetRel].translateToPlan(tableEnv)
val aggString = aggregationToString(inputType, grouping, getRowType,
namedAggregates, Nil)
- val prepareOpName = s"prepare select: ($aggString)"
- val mappedInput = inputDS.map(mapFunction).name(prepareOpName)
val rowTypeInfo =
FlinkTypeFactory.toInternalRowTypeInfo(getRowType).asInstanceOf[RowTypeInfo]
- if (groupingKeys.length > 0) {
+ if (grouping.length > 0) {
// grouped aggregation
val aggOpName = s"groupBy: (${groupingToString(inputType,
grouping)}), " +
s"select: ($aggString)"
- mappedInput.asInstanceOf[DataSet[Row]]
- .groupBy(groupingKeys: _*)
- .reduceGroup(groupReduceFunction)
- .returns(rowTypeInfo)
- .name(aggOpName)
+ if (preAgg.isDefined) {
+ inputDS
+ // pre-aggregation
+ .groupBy(grouping: _*)
+ .combineGroup(preAgg.get)
+ .returns(preAggType.get)
+ .name(aggOpName)
+ // final aggregation
+ .groupBy(grouping.indices: _*)
--- End diff --
The pre-aggregation function modifies the schema of rows. It puts all
grouping keys first, followed by all accumulators. Therefore, the following
final aggregation needs to group on the first `n` fields.
Before, the prepare mapper changed the layout.
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