Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/21699#discussion_r208478196
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/RelationalGroupedDataset.scala ---
@@ -371,25 +426,14 @@ class RelationalGroupedDataset protected[sql](
/**
* (Java-specific) Pivots a column of the current `DataFrame` and
performs the specified
- * aggregation.
- *
- * There are two versions of pivot function: one that requires the
caller to specify the list
- * of distinct values to pivot on, and one that does not. The latter is
more concise but less
- * efficient, because Spark needs to first compute the list of distinct
values internally.
+ * aggregation. This is an overloaded version of the `pivot` method with
`pivotColumn` of
+ * the `String` type.
*
- * {{{
- * // Compute the sum of earnings for each year by course with each
course as a separate column
- * df.groupBy("year").pivot("course", Arrays.<Object>asList("dotNET",
"Java")).sum("earnings");
- *
- * // Or without specifying column values (less efficient)
- * df.groupBy("year").pivot("course").sum("earnings");
- * }}}
- *
- * @param pivotColumn Name of the column to pivot.
+ * @param pivotColumn the column to pivot.
* @param values List of values that will be translated to columns in
the output DataFrame.
- * @since 1.6.0
+ * @since 2.4.0
*/
- def pivot(pivotColumn: String, values: java.util.List[Any]):
RelationalGroupedDataset = {
+ def pivot(pivotColumn: Column, values: java.util.List[Any]):
RelationalGroupedDataset = {
--- End diff --
I think it's a bad idea to use `Any` in the API. For the existing ones we
can't remove, but why should not add new ones using `Any`.
In Spark 3.0 we should audit all the APIs in `functions.scala` and make
them consistent(e.g. only use `Column` in the API)
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