sunchao commented on a change in pull request #35657:
URL: https://github.com/apache/spark/pull/35657#discussion_r829322165



##########
File path: 
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/physical/partitioning.scala
##########
@@ -305,6 +306,63 @@ case class HashPartitioning(expressions: Seq[Expression], 
numPartitions: Int)
     newChildren: IndexedSeq[Expression]): HashPartitioning = copy(expressions 
= newChildren)
 }
 
+/**
+ * Represents a partitioning where rows are split across partitions based on 
transforms defined
+ * by `expressions`. `partitionValuesOpt`, if defined, should contain value of 
partition key(s) in
+ * ascending order, after evaluated by the transforms in `expressions`, for 
each input partition.
+ * In addition, its length must be the same as the number of input partitions 
(and thus is a 1-1
+ * mapping), and each row in `partitionValuesOpt` must be unique.
+ *
+ * For example, if `expressions` is `[years(ts_col)]`, then a valid value of 
`partitionValuesOpt` is
+ * `[0, 1, 2]`, which represents 3 input partitions with distinct partition 
values. All rows
+ * in each partition have the same value for column `ts_col` (which is of 
timestamp type), after
+ * being applied by the `years` transform.

Review comment:
       Hmm I'm thinking whether we can still use `DataSourcePartitioning` for 
the V2 interface, following similar naming conventions such as `DataSourceRDD`, 
`DataSourceScanExec`, etc. As you mentioned above, `KeyGroupedPartitioning` is 
not limited to V2 sources but rather more general and can be applied to other 
things like Hive bucketing in future.




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