Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/12344#discussion_r60805954
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategy.scala
---
@@ -134,8 +134,13 @@ private[sql] object FileSourceStrategy extends
Strategy with Logging {
}
case _ =>
- val maxSplitBytes = files.sqlContext.conf.filesMaxPartitionBytes
+ val defaultMaxSplitBytes =
files.sqlContext.conf.filesMaxPartitionBytes
val openCostInBytes = files.sqlContext.conf.filesOpenCostInBytes
+ val defaultParallelism =
files.sqlContext.sparkContext.defaultParallelism
+ val totalBytes = selectedPartitions.flatMap(_.files.map(_.getLen
+ openCostInBytes)).sum
+ val maxSplitBytes = Math.max(openCostInBytes * 2,
--- End diff --
we should do max and then min, rather than min and then max to guard
against somebody setting a large openCostInBytes value.
also add some documentation explaining the algorithm inline. we should also
explain what the magic number 2 is doing.
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