viirya commented on a change in pull request #26461: [SPARK-29831][SQL] Scan
Hive partitioned table should not dramatically increase data parallelism
URL: https://github.com/apache/spark/pull/26461#discussion_r344565178
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File path: sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveUtils.scala
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@@ -155,6 +155,16 @@ private[spark] object HiveUtils extends Logging {
.booleanConf
.createWithDefault(true)
+ val HIVE_TABLE_SCAN_MAX_PARALLELISM =
buildConf("spark.sql.hive.tableScan.maxParallelism")
Review comment:
When reading a Hive partitioned table, users could get an unreasonable
number of partitions like dozens of thousands.
Hive Scan node returns a UnionRDD of Hive partitions. Each Hive partition is
read as a HadoopRDD. For each partition, the number depends on data size. But
final UnionRDD sums up all number of partitions.
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