diff --git a/src/Microsoft.Data.Analysis/DataFrameColumn.cs b/src/Microsoft.Data.Analysis/DataFrameColumn.cs
index 2085304925..afe3be4282 100644
--- a/src/Microsoft.Data.Analysis/DataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/DataFrameColumn.cs
@@ -202,6 +202,13 @@ public void SetName(string newName)
         /// <param name="length">The new length of the column</param>
         protected internal virtual void Resize(long length) => throw new NotImplementedException();
 
+        /// <summary>
+        /// Clone column to produce a copy
+        /// </summary>
+        /// <param name="numberOfNullsToAppend"></param>
+        /// <returns>A new <see cref="DataFrameColumn"/></returns>
+        public DataFrameColumn Clone(long numberOfNullsToAppend = 0) => CloneImplementation(numberOfNullsToAppend);
+
         /// <summary>
         /// Clone column to produce a copy potentially changing the order of values by supplying mapIndices and an invert flag
         /// </summary>
@@ -209,7 +216,7 @@ public void SetName(string newName)
         /// <param name="invertMapIndices"></param>
         /// <param name="numberOfNullsToAppend"></param>
         /// <returns>A new <see cref="DataFrameColumn"/></returns>
-        public virtual DataFrameColumn Clone(DataFrameColumn mapIndices = null, bool invertMapIndices = false, long numberOfNullsToAppend = 0) => CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
+        public DataFrameColumn Clone(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0) => CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
 
         /// <summary>
         /// Clone column to produce a copy potentially changing the order of values by supplying mapIndices and an invert flag
@@ -218,7 +225,9 @@ public void SetName(string newName)
         /// <param name="invertMapIndices"></param>
         /// <param name="numberOfNullsToAppend"></param>
         /// <returns>A new <see cref="DataFrameColumn"/></returns>
-        protected virtual DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend) => throw new NotImplementedException();
+        protected abstract DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend);
+
+        protected abstract DataFrameColumn CloneImplementation(long numberOfNullsToAppend = 0);
 
         /// <summary>
         /// Returns a copy of this column sorted by its values
diff --git a/src/Microsoft.Data.Analysis/DataFrameColumns/ArrowStringDataFrameColumn.cs b/src/Microsoft.Data.Analysis/DataFrameColumns/ArrowStringDataFrameColumn.cs
index 49f88eab6b..ac14541549 100644
--- a/src/Microsoft.Data.Analysis/DataFrameColumns/ArrowStringDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/DataFrameColumns/ArrowStringDataFrameColumn.cs
@@ -62,7 +62,6 @@ public ArrowStringDataFrameColumn(string name, ReadOnlyMemory<byte> values, Read
             _nullBitMapBuffers.Add(nullBitMapBuffer);
 
             _nullCount = nullCount;
-
         }
 
         private long _nullCount;
@@ -371,8 +370,32 @@ protected internal override Apache.Arrow.Array ToArrowArray(long startIndex, int
         /// <inheritdoc/>
         public override DataFrameColumn Sort(bool ascending = true) => throw new NotSupportedException();
 
+        public new ArrowStringDataFrameColumn Clone(long numberOfNullsToAppend = 0)
+        {
+            return (ArrowStringDataFrameColumn)CloneImplementation(numberOfNullsToAppend);
+        }
+
+        public new ArrowStringDataFrameColumn Clone(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
+        {
+            return (ArrowStringDataFrameColumn)CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
+        }
+
         /// <inheritdoc/>
-        public override DataFrameColumn Clone(DataFrameColumn mapIndices = null, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
+        protected override DataFrameColumn CloneImplementation(long numberOfNullsToAppend)
+        {
+            var ret = new ArrowStringDataFrameColumn(Name);
+
+            for (long i = 0; i < Length; i++)
+                ret.Append(IsValid(i) ? GetBytes(i) : default(ReadOnlySpan<byte>));
+
+            for (long i = 0; i < numberOfNullsToAppend; i++)
+                ret.Append(default);
+
+            return ret;
+        }
+
+        /// <inheritdoc/>
+        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
         {
             ArrowStringDataFrameColumn clone;
             if (!(mapIndices is null))
@@ -381,27 +404,28 @@ public override DataFrameColumn Clone(DataFrameColumn mapIndices = null, bool in
                 if (dataType != typeof(long) && dataType != typeof(int) && dataType != typeof(bool))
                     throw new ArgumentException(String.Format(Strings.MultipleMismatchedValueType, typeof(long), typeof(int), typeof(bool)), nameof(mapIndices));
                 if (mapIndices.DataType == typeof(long))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
                 else if (dataType == typeof(int))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
                 else
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<bool>);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<bool>);
+
+                for (long i = 0; i < numberOfNullsToAppend; i++)
+                    clone.Append(default);
             }
             else
             {
-                clone = Clone();
-            }
-            for (long i = 0; i < numberOfNullsToAppend; i++)
-            {
-                clone.Append(default);
+                clone = Clone(numberOfNullsToAppend);
             }
+
             return clone;
         }
 
-        private ArrowStringDataFrameColumn Clone(PrimitiveDataFrameColumn<bool> boolColumn)
+        private ArrowStringDataFrameColumn CloneImplementation(PrimitiveDataFrameColumn<bool> boolColumn)
         {
             if (boolColumn.Length > Length)
                 throw new ArgumentException(Strings.MapIndicesExceedsColumnLength, nameof(boolColumn));
+
             ArrowStringDataFrameColumn ret = new ArrowStringDataFrameColumn(Name);
             for (long i = 0; i < boolColumn.Length; i++)
             {
@@ -412,10 +436,11 @@ private ArrowStringDataFrameColumn Clone(PrimitiveDataFrameColumn<bool> boolColu
             return ret;
         }
 
-        private ArrowStringDataFrameColumn CloneImplementation<U>(PrimitiveDataFrameColumn<U> mapIndices, bool invertMapIndices = false)
+        private ArrowStringDataFrameColumn CloneImplementation<U>(PrimitiveDataFrameColumn<U> mapIndices, bool invertMapIndices)
             where U : unmanaged
         {
             ArrowStringDataFrameColumn ret = new ArrowStringDataFrameColumn(Name);
+
             mapIndices.ApplyElementwise((U? mapIndex, long rowIndex) =>
             {
                 if (mapIndex == null)
@@ -423,38 +448,14 @@ private ArrowStringDataFrameColumn CloneImplementation<U>(PrimitiveDataFrameColu
                     ret.Append(default);
                     return mapIndex;
                 }
-                if (invertMapIndices)
-                {
-                    long index = mapIndices.Length - 1 - rowIndex;
-                    ret.Append(IsValid(index) ? GetBytes(index) : default(ReadOnlySpan<byte>));
-                }
-                else
-                {
-                    ret.Append(IsValid(rowIndex) ? GetBytes(rowIndex) : default(ReadOnlySpan<byte>));
-                }
+
+                long index = invertMapIndices ? mapIndices.Length - 1 - rowIndex : rowIndex;
+                ret.Append(IsValid(index) ? GetBytes(index) : default(ReadOnlySpan<byte>));
+
                 return mapIndex;
             });
-            return ret;
-        }
 
-        private ArrowStringDataFrameColumn Clone(PrimitiveDataFrameColumn<long> mapIndices = null, bool invertMapIndex = false)
-        {
-            if (mapIndices is null)
-            {
-                ArrowStringDataFrameColumn ret = new ArrowStringDataFrameColumn(Name);
-                for (long i = 0; i < Length; i++)
-                {
-                    ret.Append(IsValid(i) ? GetBytes(i) : default(ReadOnlySpan<byte>));
-                }
-                return ret;
-            }
-            else
-                return CloneImplementation(mapIndices, invertMapIndex);
-        }
-
-        private ArrowStringDataFrameColumn Clone(PrimitiveDataFrameColumn<int> mapIndices, bool invertMapIndex = false)
-        {
-            return CloneImplementation(mapIndices, invertMapIndex);
+            return ret;
         }
 
         /// <inheritdoc/>
diff --git a/src/Microsoft.Data.Analysis/DataFrameColumns/StringDataFrameColumn.cs b/src/Microsoft.Data.Analysis/DataFrameColumns/StringDataFrameColumn.cs
index 59ded9765b..e77a71e6f0 100644
--- a/src/Microsoft.Data.Analysis/DataFrameColumns/StringDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/DataFrameColumns/StringDataFrameColumn.cs
@@ -250,6 +250,28 @@ private PrimitiveDataFrameColumn<long> GetSortIndices(Comparer<string> comparer,
         }
 
         public new StringDataFrameColumn Clone(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend)
+        {
+            return (StringDataFrameColumn)CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
+        }
+
+        public new StringDataFrameColumn Clone(long numberOfNullsToAppend = 0)
+        {
+            return (StringDataFrameColumn)CloneImplementation(numberOfNullsToAppend);
+        }
+
+        protected override DataFrameColumn CloneImplementation(long numberOfNullsToAppend)
+        {
+            StringDataFrameColumn ret = new StringDataFrameColumn(Name, Length);
+            for (long i = 0; i < Length; i++)
+                ret[i] = this[i];
+
+            for (long i = 0; i < numberOfNullsToAppend; i++)
+                ret.Append(null);
+
+            return ret;
+        }
+
+        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
         {
             StringDataFrameColumn clone;
             if (!(mapIndices is null))
@@ -258,29 +280,24 @@ public new StringDataFrameColumn Clone(DataFrameColumn mapIndices, bool invertMa
                 if (dataType != typeof(long) && dataType != typeof(int) && dataType != typeof(bool))
                     throw new ArgumentException(String.Format(Strings.MultipleMismatchedValueType, typeof(long), typeof(int), typeof(bool)), nameof(mapIndices));
                 if (mapIndices.DataType == typeof(long))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
                 else if (dataType == typeof(int))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
                 else
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<bool>);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<bool>);
+
+                for (long i = 0; i < numberOfNullsToAppend; i++)
+                    clone.Append(null);
             }
             else
             {
-                clone = Clone();
+                clone = Clone(numberOfNullsToAppend);
             }
-            for (long i = 0; i < numberOfNullsToAppend; i++)
-            {
-                clone.Append(null);
-            }
-            return clone;
-        }
 
-        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices = null, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
-        {
-            return Clone(mapIndices, invertMapIndices, numberOfNullsToAppend);
+            return clone;
         }
 
-        private StringDataFrameColumn Clone(PrimitiveDataFrameColumn<bool> boolColumn)
+        private StringDataFrameColumn CloneImplementation(PrimitiveDataFrameColumn<bool> boolColumn)
         {
             if (boolColumn.Length > Length)
                 throw new ArgumentException(Strings.MapIndicesExceedsColumnLength, nameof(boolColumn));
@@ -375,28 +392,6 @@ private StringDataFrameColumn CloneImplementation<U>(PrimitiveDataFrameColumn<U>
             return ret;
         }
 
-        private StringDataFrameColumn Clone(PrimitiveDataFrameColumn<long> mapIndices = null, bool invertMapIndex = false)
-        {
-            if (mapIndices is null)
-            {
-                StringDataFrameColumn ret = new StringDataFrameColumn(Name, Length);
-                for (long i = 0; i < Length; i++)
-                {
-                    ret[i] = this[i];
-                }
-                return ret;
-            }
-            else
-            {
-                return CloneImplementation(mapIndices, invertMapIndex);
-            }
-        }
-
-        private StringDataFrameColumn Clone(PrimitiveDataFrameColumn<int> mapIndices, bool invertMapIndex = false)
-        {
-            return CloneImplementation(mapIndices, invertMapIndex);
-        }
-
         internal static DataFrame ValueCountsImplementation(Dictionary<string, ICollection<long>> groupedValues)
         {
             StringDataFrameColumn keys = new StringDataFrameColumn("Values", 0);
diff --git a/src/Microsoft.Data.Analysis/DataFrameColumns/VBufferDataFrameColumn.cs b/src/Microsoft.Data.Analysis/DataFrameColumns/VBufferDataFrameColumn.cs
index fab98ee005..4c190d5cbe 100644
--- a/src/Microsoft.Data.Analysis/DataFrameColumns/VBufferDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/DataFrameColumns/VBufferDataFrameColumn.cs
@@ -5,7 +5,6 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Data;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using Microsoft.ML;
@@ -210,7 +209,7 @@ protected internal override void AddValueUsingCursor(DataViewRowCursor cursor, D
             }
         }
 
-        private VBufferDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<bool> boolColumn)
+        private VBufferDataFrameColumn<T> CloneImplementation(PrimitiveDataFrameColumn<bool> boolColumn)
         {
             if (boolColumn.Length > Length)
                 throw new ArgumentException(Strings.MapIndicesExceedsColumnLength, nameof(boolColumn));
@@ -224,28 +223,6 @@ private VBufferDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<bool> boolColum
             return ret;
         }
 
-        private VBufferDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<long> mapIndices = null, bool invertMapIndex = false)
-        {
-            if (mapIndices is null)
-            {
-                VBufferDataFrameColumn<T> ret = new VBufferDataFrameColumn<T>(Name, Length);
-                for (long i = 0; i < Length; i++)
-                {
-                    ret[i] = this[i];
-                }
-                return ret;
-            }
-            else
-            {
-                return CloneImplementation(mapIndices, invertMapIndex);
-            }
-        }
-
-        private VBufferDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<int> mapIndices, bool invertMapIndex = false)
-        {
-            return CloneImplementation(mapIndices, invertMapIndex);
-        }
-
         private VBufferDataFrameColumn<T> CloneImplementation<U>(PrimitiveDataFrameColumn<U> mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
            where U : unmanaged
         {
@@ -314,6 +291,16 @@ private VBufferDataFrameColumn<T> CloneImplementation<U>(PrimitiveDataFrameColum
         }
 
         public new VBufferDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend)
+        {
+            return (VBufferDataFrameColumn<T>)CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
+        }
+
+        public new VBufferDataFrameColumn<T> Clone(long numberOfNullsToAppend = 0)
+        {
+            return (VBufferDataFrameColumn<T>)CloneImplementation(numberOfNullsToAppend);
+        }
+
+        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
         {
             VBufferDataFrameColumn<T> clone;
             if (!(mapIndices is null))
@@ -322,11 +309,11 @@ public new VBufferDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool inve
                 if (dataType != typeof(long) && dataType != typeof(int) && dataType != typeof(bool))
                     throw new ArgumentException(String.Format(Strings.MultipleMismatchedValueType, typeof(long), typeof(int), typeof(bool)), nameof(mapIndices));
                 if (mapIndices.DataType == typeof(long))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<long>, invertMapIndices);
                 else if (dataType == typeof(int))
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
                 else
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<bool>);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<bool>);
             }
             else
             {
@@ -336,9 +323,14 @@ public new VBufferDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool inve
             return clone;
         }
 
-        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices = null, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
+        protected override DataFrameColumn CloneImplementation(long numberOfNullsToAppend)
         {
-            return Clone(mapIndices, invertMapIndices, numberOfNullsToAppend);
+            var ret = new VBufferDataFrameColumn<T>(Name, Length);
+
+            for (long i = 0; i < Length; i++)
+                ret[i] = this[i];
+
+            return ret;
         }
 
         private static VectorDataViewType GetDataViewType()
diff --git a/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs b/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
index f29f4963d7..3d3f740318 100644
--- a/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
@@ -63,8 +63,7 @@ public IEnumerable<ReadOnlyMemory<T>> GetReadOnlyDataBuffers()
         {
             for (int i = 0; i < _columnContainer.Buffers.Count; i++)
             {
-                ReadOnlyDataFrameBuffer<T> buffer = _columnContainer.Buffers[i];
-                yield return buffer.ReadOnlyMemory;
+                yield return _columnContainer.Buffers[i].ReadOnlyMemory;
             }
         }
 
@@ -364,13 +363,29 @@ public override bool HasDescription()
         }
 
         /// <summary>
-        /// Returns a clone of this column
+        /// Returns a clone of this column.
+        /// </summary>
+        /// <param name="numberOfNullsToAppend"></param>
+        /// <returns></returns>
+        public new PrimitiveDataFrameColumn<T> Clone(long numberOfNullsToAppend = 0)
+        {
+            return (PrimitiveDataFrameColumn<T>)CloneImplementation(numberOfNullsToAppend);
+        }
+
+        /// <summary>
+        /// Returns a clone of this column.
         /// </summary>
         /// <param name="mapIndices">A column who values are used as indices </param>
         /// <param name="invertMapIndices"></param>
         /// <param name="numberOfNullsToAppend"></param>
         /// <returns></returns>
-        public new PrimitiveDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend)
+        public new PrimitiveDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool invertMapIndices = false, long numberOfNullsToAppend = 0)
+        {
+            return (PrimitiveDataFrameColumn<T>)CloneImplementation(mapIndices, invertMapIndices, numberOfNullsToAppend);
+        }
+
+        /// <inheritdoc/>
+        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend)
         {
             PrimitiveDataFrameColumn<T> clone;
             if (!(mapIndices is null))
@@ -383,24 +398,31 @@ public new PrimitiveDataFrameColumn<T> Clone(DataFrameColumn mapIndices, bool in
                 else if (dataType == typeof(int))
                     clone = Clone(mapIndices as PrimitiveDataFrameColumn<int>, invertMapIndices);
                 else
-                    clone = Clone(mapIndices as PrimitiveDataFrameColumn<bool>);
+                    clone = CloneImplementation(mapIndices as PrimitiveDataFrameColumn<bool>);
+
+                if (numberOfNullsToAppend != 0)
+                    clone.AppendMany(null, numberOfNullsToAppend);
             }
             else
             {
                 clone = Clone();
             }
-            Debug.Assert(!ReferenceEquals(clone, null));
-            clone.AppendMany(null, numberOfNullsToAppend);
+
             return clone;
         }
 
-        /// <inheritdoc/>
-        protected override DataFrameColumn CloneImplementation(DataFrameColumn mapIndices, bool invertMapIndices, long numberOfNullsToAppend)
+        protected override DataFrameColumn CloneImplementation(long numberOfNullsToAppend)
         {
-            return Clone(mapIndices, invertMapIndices, numberOfNullsToAppend);
+            var newColumnContainer = _columnContainer.Clone();
+            var clone = CreateNewColumn(Name, newColumnContainer);
+
+            if (numberOfNullsToAppend != 0)
+                clone.AppendMany(null, numberOfNullsToAppend);
+
+            return clone;
         }
 
-        private PrimitiveDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<bool> boolColumn)
+        private PrimitiveDataFrameColumn<T> CloneImplementation(PrimitiveDataFrameColumn<bool> boolColumn)
         {
             if (boolColumn.Length > Length)
                 throw new ArgumentException(Strings.MapIndicesExceedsColumnLength, nameof(boolColumn));
@@ -436,21 +458,19 @@ private PrimitiveDataFrameColumn<T> CloneImplementation<U>(PrimitiveDataFrameCol
             return ret;
         }
 
-        public PrimitiveDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<long> mapIndices = null, bool invertMapIndices = false)
+        public PrimitiveDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<long> mapIndices, bool invertMapIndices = false)
         {
             if (mapIndices is null)
-            {
-                PrimitiveColumnContainer<T> newColumnContainer = _columnContainer.Clone();
-                return CreateNewColumn(Name, newColumnContainer);
-            }
-            else
-            {
-                return CloneImplementation(mapIndices, invertMapIndices);
-            }
+                return Clone();
+
+            return CloneImplementation(mapIndices, invertMapIndices);
         }
 
         public PrimitiveDataFrameColumn<T> Clone(PrimitiveDataFrameColumn<int> mapIndices, bool invertMapIndices = false)
         {
+            if (mapIndices is null)
+                return Clone();
+
             return CloneImplementation(mapIndices, invertMapIndices);
         }