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_r363161197
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/udaf.scala
##########
@@ -450,3 +454,88 @@ 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()
+ private[this] lazy val bufferEncoder =
agg.bufferEncoder.asInstanceOf[ExpressionEncoder[BUF]]
+ private[this] lazy val outputEncoder =
agg.outputEncoder.asInstanceOf[ExpressionEncoder[OUT]]
+
+ def dataType: DataType = outputEncoder.objSerializer.dataType
+
+ def inputTypes: Seq[DataType] = inputEncoder.schema.map(_.dataType)
+
+ def nullable: Boolean = isNullable
+
+ override lazy val deterministic: Boolean = isDeterministic
+
+ def withNewMutableAggBufferOffset(newMutableAggBufferOffset: Int):
ScalaAggregator[IN, BUF, OUT] =
+ copy(mutableAggBufferOffset = newMutableAggBufferOffset)
+
+ def withNewInputAggBufferOffset(newInputAggBufferOffset: Int):
ScalaAggregator[IN, BUF, OUT] =
+ copy(inputAggBufferOffset = newInputAggBufferOffset)
+
+ private[this] lazy val childrenSchema: StructType = {
+ val inputFields = children.zipWithIndex.map {
+ case (child, index) =>
+ StructField(s"input$index", child.dataType, child.nullable,
Metadata.empty)
+ }
+ StructType(inputFields)
+ }
+
+ private[this] lazy val inputProjection = {
+ val inputAttributes = childrenSchema.toAttributes
+ log.debug(
+ s"Creating MutableProj: $children, inputSchema: $inputAttributes.")
+ UnsafeProjection.create(children, inputAttributes)
Review comment:
Ah now I got it. This is not simply converting row to unsafe row, this is
evaluating the children, in case we have something like `func(a + 1, b * 2)`,
we need to evaluate the input parameters first.
That said, the `children` should have been already bound, so we only need
to write
```
// A projection to evaluate the input expressions of this function.
lazy val inputProjection = UnsafeProjection.create(children)
```
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