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_r363016122
##########
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],
+ inputEncoder: 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 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)
+ }
+
+ def createAggregationBuffer(): BUF = agg.zero
+
+ def update(buffer: BUF, input: InternalRow): BUF = {
+ val proj = inputProjection(input)
+ val a = inputEncoder.fromRow(proj)
+ agg.reduce(buffer, a)
+ }
+
+ def merge(buffer: BUF, input: BUF): BUF = agg.merge(buffer, input)
+
+ private[this] lazy val outputToCatalystConverter: Any => Any = {
+ CatalystTypeConverters.createToCatalystConverter(dataType)
+ }
+
+ def eval(buffer: BUF): Any = {
+ val row = outputEncoder.toRow(agg.finish(buffer))
+ if (outputEncoder.isSerializedAsStruct) row else row.get(0, dataType)
+ }
+
+ private[this] lazy val bufferSerializer = bufferEncoder.namedExpressions
+ private[this] lazy val bufferDeserializer =
bufferEncoder.resolveAndBind().deserializer
+ private[this] lazy val bufferObjToRow =
UnsafeProjection.create(bufferSerializer)
+ private[this] lazy val bufferRow = new UnsafeRow(bufferSerializer.length)
+ private[this] lazy val bufferRowToObject =
+ GenerateSafeProjection.generate(bufferDeserializer :: Nil)
+
+ def serialize(agg: BUF): Array[Byte] =
bufferObjToRow(InternalRow(agg)).getBytes
Review comment:
The code you write here is almost the same with `ExpressionEncoder`: create
2 projects to implement obj <-> row. That's why I suggest using
`ExpressionEncoder` directly.
Without changing return type, we can do
`bufferEncoder.toRow(obj).asInstanceOf[UnsafeRow].getBytes`
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