Github user yhuai commented on a diff in the pull request:
https://github.com/apache/spark/pull/9364#discussion_r43452005
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/partitioning.scala
---
@@ -38,3 +38,11 @@ case class SortPartitions(sortExpressions:
Seq[SortOrder], child: LogicalPlan)
*/
case class RepartitionByExpression(partitionExpressions: Seq[Expression],
child: LogicalPlan)
extends RedistributeData
+
+/**
+ * This method repartitions data using [[Expression]]s into
`numPartitions`. If numPartitions is
+ * less than zero, a default is used. Otherwise this behaves identically
to RepartitionByExpression.
+ */
+case class PartitionByExpression(partitionExpressions: Seq[Expression],
+ child: LogicalPlan, numPartitions: Int =
-1)
+ extends RedistributeData
--- End diff --
How about we just use `RepartitionByExpression`? Since users do not use
classes in catalyst directly, it is fine to change the signature of the
constructor. For the type of `numPartitions`, how about `Option[Int]`? If it is
`None`, the number of partition is not specified. We can add a `require` clause
to make sure this value is larger than 0 if `numPartitions` is a `Some`.
btw, regarding the format, the following one is preferred.
```
case class PartitionByExpression(
partitionExpressions: Seq[Expression],
numPartitions: Option[Int] = None,
child: LogicalPlan)
extends RedistributeData
```
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