diff --git a/python/pyspark/sql/dataframe.py b/python/pyspark/sql/dataframe.py
index 273a40dd526cf..1e9c657cf81b3 100644
--- a/python/pyspark/sql/dataframe.py
+++ b/python/pyspark/sql/dataframe.py
@@ -802,11 +802,11 @@ def groupBy(self, *cols):
             Each element should be a column name (string) or an expression (:class:`Column`).
 
         >>> df.groupBy().avg().collect()
-        [Row(AVG(age)=3.5)]
+        [Row(avg(age)=3.5)]
         >>> df.groupBy('name').agg({'age': 'mean'}).collect()
-        [Row(name=u'Alice', AVG(age)=2.0), Row(name=u'Bob', AVG(age)=5.0)]
+        [Row(name=u'Alice', avg(age)=2.0), Row(name=u'Bob', avg(age)=5.0)]
         >>> df.groupBy(df.name).avg().collect()
-        [Row(name=u'Alice', AVG(age)=2.0), Row(name=u'Bob', AVG(age)=5.0)]
+        [Row(name=u'Alice', avg(age)=2.0), Row(name=u'Bob', avg(age)=5.0)]
         >>> df.groupBy(['name', df.age]).count().collect()
         [Row(name=u'Bob', age=5, count=1), Row(name=u'Alice', age=2, count=1)]
         """
@@ -864,10 +864,10 @@ def agg(self, *exprs):
         (shorthand for ``df.groupBy.agg()``).
 
         >>> df.agg({"age": "max"}).collect()
-        [Row(MAX(age)=5)]
+        [Row(max(age)=5)]
         >>> from pyspark.sql import functions as F
         >>> df.agg(F.min(df.age)).collect()
-        [Row(MIN(age)=2)]
+        [Row(min(age)=2)]
         """
         return self.groupBy().agg(*exprs)
 
diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index 4e2be88e9e3b9..f9a15d4a66309 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -266,7 +266,7 @@ def coalesce(*cols):
 
     >>> cDf.select(coalesce(cDf["a"], cDf["b"])).show()
     +-------------+
-    |Coalesce(a,b)|
+    |coalesce(a,b)|
     +-------------+
     |         null|
     |            1|
@@ -275,7 +275,7 @@ def coalesce(*cols):
 
     >>> cDf.select('*', coalesce(cDf["a"], lit(0.0))).show()
     +----+----+---------------+
-    |   a|   b|Coalesce(a,0.0)|
+    |   a|   b|coalesce(a,0.0)|
     +----+----+---------------+
     |null|null|            0.0|
     |   1|null|            1.0|
diff --git a/python/pyspark/sql/group.py b/python/pyspark/sql/group.py
index 5a37a673ee80c..04594d5a836ce 100644
--- a/python/pyspark/sql/group.py
+++ b/python/pyspark/sql/group.py
@@ -75,11 +75,11 @@ def agg(self, *exprs):
 
         >>> gdf = df.groupBy(df.name)
         >>> gdf.agg({"*": "count"}).collect()
-        [Row(name=u'Alice', COUNT(1)=1), Row(name=u'Bob', COUNT(1)=1)]
+        [Row(name=u'Alice', count(1)=1), Row(name=u'Bob', count(1)=1)]
 
         >>> from pyspark.sql import functions as F
         >>> gdf.agg(F.min(df.age)).collect()
-        [Row(name=u'Alice', MIN(age)=2), Row(name=u'Bob', MIN(age)=5)]
+        [Row(name=u'Alice', min(age)=2), Row(name=u'Bob', min(age)=5)]
         """
         assert exprs, "exprs should not be empty"
         if len(exprs) == 1 and isinstance(exprs[0], dict):
@@ -110,9 +110,9 @@ def mean(self, *cols):
         :param cols: list of column names (string). Non-numeric columns are ignored.
 
         >>> df.groupBy().mean('age').collect()
-        [Row(AVG(age)=3.5)]
+        [Row(avg(age)=3.5)]
         >>> df3.groupBy().mean('age', 'height').collect()
-        [Row(AVG(age)=3.5, AVG(height)=82.5)]
+        [Row(avg(age)=3.5, avg(height)=82.5)]
         """
 
     @df_varargs_api
@@ -125,9 +125,9 @@ def avg(self, *cols):
         :param cols: list of column names (string). Non-numeric columns are ignored.
 
         >>> df.groupBy().avg('age').collect()
-        [Row(AVG(age)=3.5)]
+        [Row(avg(age)=3.5)]
         >>> df3.groupBy().avg('age', 'height').collect()
-        [Row(AVG(age)=3.5, AVG(height)=82.5)]
+        [Row(avg(age)=3.5, avg(height)=82.5)]
         """
 
     @df_varargs_api
@@ -136,9 +136,9 @@ def max(self, *cols):
         """Computes the max value for each numeric columns for each group.
 
         >>> df.groupBy().max('age').collect()
-        [Row(MAX(age)=5)]
+        [Row(max(age)=5)]
         >>> df3.groupBy().max('age', 'height').collect()
-        [Row(MAX(age)=5, MAX(height)=85)]
+        [Row(max(age)=5, max(height)=85)]
         """
 
     @df_varargs_api
@@ -149,9 +149,9 @@ def min(self, *cols):
         :param cols: list of column names (string). Non-numeric columns are ignored.
 
         >>> df.groupBy().min('age').collect()
-        [Row(MIN(age)=2)]
+        [Row(min(age)=2)]
         >>> df3.groupBy().min('age', 'height').collect()
-        [Row(MIN(age)=2, MIN(height)=80)]
+        [Row(min(age)=2, min(height)=80)]
         """
 
     @df_varargs_api
@@ -162,9 +162,9 @@ def sum(self, *cols):
         :param cols: list of column names (string). Non-numeric columns are ignored.
 
         >>> df.groupBy().sum('age').collect()
-        [Row(SUM(age)=7)]
+        [Row(sum(age)=7)]
         >>> df3.groupBy().sum('age', 'height').collect()
-        [Row(SUM(age)=7, SUM(height)=165)]
+        [Row(sum(age)=7, sum(height)=165)]
         """
 
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
index da520f56b430e..64e07bd2a17db 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
@@ -94,7 +94,6 @@ case class Min(child: Expression) extends PartialAggregate with trees.UnaryNode[
 
   override def nullable: Boolean = true
   override def dataType: DataType = child.dataType
-  override def toString: String = s"MIN($child)"
 
   override def asPartial: SplitEvaluation = {
     val partialMin = Alias(Min(child), "PartialMin")()
@@ -388,6 +387,8 @@ case class ApproxCountDistinct(child: Expression, relativeSD: Double = 0.05)
 
 case class Average(child: Expression) extends PartialAggregate with trees.UnaryNode[Expression] {
 
+  override def prettyName: String = "avg"
+
   override def nullable: Boolean = true
 
   override def dataType: DataType = child.dataType match {