1 files changed, 14 insertions, 0 deletions
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/CentralMomentAgg.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/CentralMomentAgg.scala
index 9d2db45144..17a7c6dce8 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/CentralMomentAgg.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/CentralMomentAgg.scala
@@ -130,6 +130,10 @@ abstract class CentralMomentAgg(child: Expression) extends DeclarativeAggregate
 }
 
 // Compute the population standard deviation of a column
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the population standard deviation calculated from values of a group.")
+// scalastyle:on line.size.limit
 case class StddevPop(child: Expression) extends CentralMomentAgg(child) {
 
   override protected def momentOrder = 2
@@ -143,6 +147,8 @@ case class StddevPop(child: Expression) extends CentralMomentAgg(child) {
 }
 
 // Compute the sample standard deviation of a column
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the sample standard deviation calculated from values of a group.")
 case class StddevSamp(child: Expression) extends CentralMomentAgg(child) {
 
   override protected def momentOrder = 2
@@ -157,6 +163,8 @@ case class StddevSamp(child: Expression) extends CentralMomentAgg(child) {
 }
 
 // Compute the population variance of a column
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the population variance calculated from values of a group.")
 case class VariancePop(child: Expression) extends CentralMomentAgg(child) {
 
   override protected def momentOrder = 2
@@ -170,6 +178,8 @@ case class VariancePop(child: Expression) extends CentralMomentAgg(child) {
 }
 
 // Compute the sample variance of a column
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the sample variance calculated from values of a group.")
 case class VarianceSamp(child: Expression) extends CentralMomentAgg(child) {
 
   override protected def momentOrder = 2
@@ -183,6 +193,8 @@ case class VarianceSamp(child: Expression) extends CentralMomentAgg(child) {
   override def prettyName: String = "var_samp"
 }
 
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the Skewness value calculated from values of a group.")
 case class Skewness(child: Expression) extends CentralMomentAgg(child) {
 
   override def prettyName: String = "skewness"
@@ -196,6 +208,8 @@ case class Skewness(child: Expression) extends CentralMomentAgg(child) {
   }
 }
 
+@ExpressionDescription(
+  usage = "_FUNC_(x) - Returns the Kurtosis value calculated from values of a group.")
 case class Kurtosis(child: Expression) extends CentralMomentAgg(child) {
 
   override protected def momentOrder = 4