ueshin commented on a change in pull request #25728: [SPARK-29020][WIP][SQL]
Improving array_sort behaviour
URL: https://github.com/apache/spark/pull/25728#discussion_r344934124
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/higherOrderFunctions.scala
##########
@@ -285,6 +286,116 @@ case class ArrayTransform(
override def prettyName: String = "transform"
}
+/**
+ * Sorts elements in an array using a comparator function.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(expr, func) - Sorts the input array in ascending order. The
elements of the " +
+ "input array must be orderable. Null elements will be placed at the end of
the returned " +
+ "array. Since 3.0.0 also sorts and returns the array based on the given " +
+ "comparator function. The comparator will take two nullable arguments " +
+ "representing two nullable elements of the array." +
+ "It returns -1, 0, or 1 as the first nullable element is less than, equal
to, or greater " +
+ "than the second nullable element. If the comparator function returns
other " +
+ "values (including NULL), the query will fail and raise an error.",
+ examples = """
+ Examples:
+ > SELECT _FUNC_(array(5, 6, 1), (left, right) ->
+ If(And(IsNull(left), IsNull(right)), 0,
+ If(IsNull(left), 1, If(IsNull(right), -1,
+ If(LessThan(left, right), -1, If(GreaterThan(left, right), 1,
0)))));
+ [1,5,6]
+ > SELECT _FUNC_(array('bc', 'ab', 'dc'), (left, right) ->
+ If(And(IsNull(left), IsNull(right)), 0,
+ If(IsNull(left), 1, If(IsNull(right), -1,
+ If(LessThan(left, right), -1, If(GreaterThan(left, right), 1,
0)))));
+ ["dc", "bc", "ab"]
Review comment:
Seems like these commands are not checked. We need to fit in one line. We
can use `// scalastyle:off line.size.limit` if the command is not fit in one
line.
E.g., see `ZipWith`.
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