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[SPARK-29348][SQL][FOLLOWUP] Fix slight bug on streaming example for Dataset.observe #27046

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HeartSaVioR wants to merge 1 commit into from
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[SPARK-29348][SQL][FOLLOWUP] Fix slight bug on streaming example for Dataset.observe #27046

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11 changes: 6 additions & 5 deletions sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1891,14 +1891,10 @@ class Dataset[T] private[sql](
* [[org.apache.spark.sql.util.QueryExecutionListener]] to the spark session.
*
* {{{
* // Observe row count (rc) and error row count (erc) in the streaming Dataset
* val observed_ds = ds.observe("my_event", count(lit(1)).as("rc"), count($"error").as("erc"))
* observed_ds.writeStream.format("...").start()
*
* // Monitor the metrics using a listener.
* spark.streams.addListener(new StreamingQueryListener() {
* override def onQueryProgress(event: QueryProgressEvent): Unit = {
* event.progress.observedMetrics.get("my_event").foreach { row =>
* event.progress.observedMetrics.asScala.get("my_event").foreach { row =>
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@HeartSaVioR HeartSaVioR Dec 30, 2019

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This was a minor bug on example: unlike observedMetrics available in QueryExecutionListener, event.progress.observedMetrics is a "Java" Map instead of "Scala" Map, hence to use foreach it needs asScala to convert to Scala Map.

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@srowen srowen Dec 30, 2019

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Sounds fine. The alternative is to wrap it in Option(....get(...)).foreach but that's messier

* // Trigger if the number of errors exceeds 5 percent
* val num_rows = row.getAs[Long]("rc")
* val num_error_rows = row.getAs[Long]("erc")
Expand All @@ -1908,7 +1904,12 @@ class Dataset[T] private[sql](
* }
* }
* }
* def onQueryStarted(event: QueryStartedEvent): Unit = {}
* def onQueryTerminated(event: QueryTerminatedEvent): Unit = {}
* })
* // Observe row count (rc) and error row count (erc) in the streaming Dataset
* val observed_ds = ds.observe("my_event", count(lit(1)).as("rc"), count($"error").as("erc"))
* observed_ds.writeStream.format("...").start()
* }}}
*
* @group typedrel
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