sunjincheng121 commented on a change in pull request #7235: [FLINK-10976]
[table] Add support for aggregate to table API
URL: https://github.com/apache/flink/pull/7235#discussion_r244676544
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
##########
@@ -1226,3 +1301,81 @@ class WindowGroupedTable(
select(withResolvedAggFunctionCall: _*)
}
}
+
+class AggregatedTable(
+ private[flink] val table: Table,
+ private[flink] val groupKeys: Seq[Expression],
+ private[flink] val aggregateFunction: Expression) {
+
+ /**
+ * Performs a selection operation after an aggregate operation. The field
expressions
+ * cannot contain table functions and aggregations.
+ *
+ * Example:
+ *
+ * {{{
+ * val aggFunc: AggregateFunction[_, _] = new MyAggregateFunction
+ * tableEnv.registerFunction("aggFunc", aggFunc);
+ * table.groupBy('key).aggregate("aggFunc(a, b) as (f0, f1,
f2)").select('key, 'f0, 'f1)
+ * }}}
+ */
+ def select(fields: Expression*): Table = {
+ val tableEnv = table.tableEnv
+ val (aggNames, propNames) =
extractAggregationsAndProperties(Seq(aggregateFunction), tableEnv)
+ val projectsOnAgg = replaceAggregationsAndProperties(
+ groupKeys ++ Seq(aggregateFunction), tableEnv, aggNames, propNames)
+ val projectFields = extractFieldReferences(groupKeys ++
Seq(aggregateFunction))
+
+ val aggTable = new Table(tableEnv,
+ Project(projectsOnAgg,
+ Aggregate(groupKeys, aggNames.map(a => Alias(a._1, a._2)).toSeq,
+ Project(projectFields, table.logicalPlan).validate(tableEnv)
+ ).validate(tableEnv)
+ ).validate(tableEnv))
+
+ // expand the aggregate results
+ val projectsOnAggTable =
+ aggTable.logicalPlan.output.take(groupKeys.length) ++
+ expandProjectList(
+ Seq(Flattening(aggTable.logicalPlan.output.last)),
+ aggTable.logicalPlan,
+ tableEnv).zip(extractFieldNames(aggregateFunction)).map(a =>
Alias(a._1, a._2))
+
+ val flattenedAggTable = new Table(
+ tableEnv,
+ Project(
+ projectsOnAggTable.map(UnresolvedAlias),
+ aggTable.logicalPlan).validate(tableEnv))
+
+ val expandedFields = expandProjectList(fields,
flattenedAggTable.logicalPlan, tableEnv)
+ // check there are no aggregate functions in the select after aggregate
+ expandedFields.foreach { f =>
+ unwrap(f, tableEnv) match {
+ case _: TableFunctionCall | _: Aggregation =>
+ throw new ValidationException(
+ "Cannot use TableFunction or AggregateFunction in the select after
aggregate.")
+ case _ =>
+ }
+ }
+
+ new Table(tableEnv,
+ Project(expandedFields.map(UnresolvedAlias),
flattenedAggTable.logicalPlan)
+ .validate(tableEnv))
+ }
+
+ /**
+ * Performs a selection operation after an aggregate operation. The field
expressions
+ * cannot contain table functions and aggregations.
+ *
+ * Example:
+ *
+ * {{{
+ * val aggFunc: AggregateFunction[_, _] = new MyAggregateFunction
Review comment:
`val aggFunc: AggregateFunction[_, _]` -> `val aggFunc`
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