Github user uncleGen commented on a diff in the pull request:
https://github.com/apache/spark/pull/17141#discussion_r104073535
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/statefulOperators.scala
---
@@ -397,3 +402,110 @@ object StreamingDeduplicateExec {
private val EMPTY_ROW =
UnsafeProjection.create(Array[DataType](NullType)).apply(InternalRow.apply(null))
}
+
+/**
+ * Physical operator for executing streaming Sampling.
+ *
+ * @param k random sample k elements.
+ */
+case class StreamingReservoirSampleExec(
+ keyExpressions: Seq[Attribute],
+ child: SparkPlan,
+ k: Int,
+ stateId: Option[OperatorStateId] = None,
+ eventTimeWatermark: Option[Long] = None,
+ outputMode: Option[OutputMode] = None)
+ extends UnaryExecNode with StateStoreWriter with WatermarkSupport {
+
+ override def requiredChildDistribution: Seq[Distribution] =
+ ClusteredDistribution(keyExpressions) :: Nil
+
+ private val enc = Encoders.STRING.asInstanceOf[ExpressionEncoder[String]]
+ private val NUM_RECORDS_IN_PARTITION =
enc.toRow("NUM_RECORDS_IN_PARTITION")
+ .asInstanceOf[UnsafeRow]
+
+ override protected def doExecute(): RDD[InternalRow] = {
+ metrics
+ val fieldTypes = (keyExpressions.map(_.dataType) ++
Seq(LongType)).toArray
+ val withSumFieldTypes = (keyExpressions.map(_.dataType) ++
Seq(LongType)).toArray
+
+ child.execute().mapPartitionsWithStateStore(
+ getStateId.checkpointLocation,
+ getStateId.operatorId,
+ getStateId.batchId,
+ keyExpressions.toStructType,
+ child.output.toStructType,
+ sqlContext.sessionState,
+ Some(sqlContext.streams.stateStoreCoordinator)) { (store, iter) =>
+
+ val numRecordsInPart = store.get(NUM_RECORDS_IN_PARTITION).map(value
=> {
+ value.get(0, LongType).asInstanceOf[Long]
+ }).getOrElse(0L)
+
+ val seed = Random.nextLong()
+ val rand = new XORShiftRandom(seed)
+ var numSamples = numRecordsInPart
+ var count = 0
+
+ val baseIterator = watermarkPredicate match {
+ case Some(predicate) => iter.filter((row: InternalRow) =>
!predicate.eval(row))
+ case None => iter
+ }
+
+ baseIterator.foreach { r =>
+ count += 1
+ if (numSamples < k) {
+ numSamples += 1
+ store.put(enc.toRow(numSamples.toString).asInstanceOf[UnsafeRow],
+ r.asInstanceOf[UnsafeRow])
+ } else {
+ val randomIdx = (rand.nextDouble() * (numRecordsInPart +
count)).toLong
+ if (randomIdx <= k) {
+ val replacementIdx =
enc.toRow(randomIdx.toString).asInstanceOf[UnsafeRow]
+ store.put(replacementIdx, r.asInstanceOf[UnsafeRow])
+ }
+ }
+ }
+
+ val numRecordsTillNow =
UnsafeProjection.create(Array[DataType](LongType))
+ .apply(InternalRow.apply(numRecordsInPart + count))
+ store.put(NUM_RECORDS_IN_PARTITION, numRecordsTillNow)
+ store.commit()
+
+ outputMode match {
+ case Some(Complete) =>
+ CompletionIterator[InternalRow, Iterator[InternalRow]](
+ store.iterator().filter(kv => {
+
!kv._1.asInstanceOf[UnsafeRow].equals(NUM_RECORDS_IN_PARTITION)
+ }).map(kv => {
+
UnsafeProjection.create(withSumFieldTypes).apply(InternalRow.fromSeq(
+ new JoinedRow(kv._2, numRecordsTillNow)
+ .toSeq(withSumFieldTypes)))
+ }), {})
+ case Some(Update) =>
+ CompletionIterator[InternalRow, Iterator[InternalRow]](
+ store.updates()
+ .filter(update =>
!update.key.equals(NUM_RECORDS_IN_PARTITION))
+ .map(update => {
+
UnsafeProjection.create(withSumFieldTypes).apply(InternalRow.fromSeq(
+ new JoinedRow(update.value, numRecordsTillNow)
+ .toSeq(withSumFieldTypes)))
--- End diff --
same
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