cloud-fan commented on a change in pull request #25024: [SPARK-27296][SQL]
Allows Aggregator to be registered as a UDF
URL: https://github.com/apache/spark/pull/25024#discussion_r363017167
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/udaf.scala
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@@ -450,3 +454,85 @@ case class ScalaUDAF(
override def nodeName: String = udaf.getClass.getSimpleName
}
+
+case class ScalaAggregator[IN, BUF, OUT](
+ children: Seq[Expression],
+ agg: Aggregator[IN, BUF, OUT],
+ inputEncoderNR: ExpressionEncoder[IN],
+ isNullable: Boolean = true,
+ isDeterministic: Boolean = true,
+ mutableAggBufferOffset: Int = 0,
+ inputAggBufferOffset: Int = 0)
+ extends TypedImperativeAggregate[BUF]
+ with NonSQLExpression
+ with UserDefinedExpression
+ with ImplicitCastInputTypes
+ with Logging {
+
+ private[this] lazy val inputEncoder = inputEncoderNR.resolveAndBind()
Review comment:
ah wait, just realized we miss an important feature: type check. If the
aggregator accepts int input, but the actual input column is string, what shall
we do?
Looking at `ScalaUDAF`, we implement `ImplicitCastInputTypes` and define the
expected input types. I think we should do the same thing for
`ScalaAggregator`, and add tests for it.
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