cloud-fan commented on a change in pull request #27530: [SPARK-30780][SQL]
Empty LocalTableScan should use RDD without partitions
URL: https://github.com/apache/spark/pull/27530#discussion_r377569895
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/LocalTableScanExec.scala
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@@ -45,10 +45,14 @@ case class LocalTableScanExec(
}
}
- private lazy val numParallelism: Int = math.min(math.max(unsafeRows.length,
1),
- sqlContext.sparkContext.defaultParallelism)
-
- private lazy val rdd = sqlContext.sparkContext.parallelize(unsafeRows,
numParallelism)
+ @transient private lazy val rdd: RDD[InternalRow] = {
+ if (rows.isEmpty) {
+ sqlContext.sparkContext.emptyRDD
+ } else {
+ val numSlices = math.min(unsafeRows.length,
sqlContext.sparkContext.defaultParallelism)
+ sqlContext.sparkContext.parallelize(unsafeRows, numSlices)
Review comment:
`parallelize` need to respect the `numSlices` parameter, even if the data is
empty.
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