From c77f5f7297118cc05dfe9507a452c356ab9afe38 Mon Sep 17 00:00:00 2001
From: Aleksei Smirnov <tlalok@inbox.ru>
Date: Mon, 16 Oct 2023 15:01:42 +0300
Subject: [PATCH 1/2] Avoid Boxing/Unboxing on accessing elements of
 VBufferDataFrameColumn

---
 .../PrimitiveDataFrameColumn.cs                      | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs b/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
index 54fc1744a2..7991d6b728 100644
--- a/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.cs
@@ -250,17 +250,7 @@ protected override void SetValue(long rowIndex, object value)
         public new T? this[long rowIndex]
         {
             get => GetTypedValue(rowIndex);
-            set
-            {
-                if (value == null || value.GetType() == typeof(T))
-                {
-                    _columnContainer[rowIndex] = value;
-                }
-                else
-                {
-                    throw new ArgumentException(string.Format(Strings.MismatchedValueType, DataType), nameof(value));
-                }
-            }
+            set => _columnContainer[rowIndex] = value;
         }
 
         public override double Median()

From f0ac9544a3ae7c277c11ea2d33856a78b884f324 Mon Sep 17 00:00:00 2001
From: Aleksei Smirnov <tlalok@inbox.ru>
Date: Tue, 17 Oct 2023 13:32:40 +0300
Subject: [PATCH 2/2] Avoid boxing for vbuffer column

---
 .../VBufferDataFrameColumn.cs                 | 38 ++++++++++---------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/src/Microsoft.Data.Analysis/VBufferDataFrameColumn.cs b/src/Microsoft.Data.Analysis/VBufferDataFrameColumn.cs
index fc15c873cb..064f9cf433 100644
--- a/src/Microsoft.Data.Analysis/VBufferDataFrameColumn.cs
+++ b/src/Microsoft.Data.Analysis/VBufferDataFrameColumn.cs
@@ -18,7 +18,6 @@ namespace Microsoft.Data.Analysis
     /// </summary>
     public partial class VBufferDataFrameColumn<T> : DataFrameColumn, IEnumerable<VBuffer<T>>
     {
-
         public static int MaxCapacity = ArrayUtility.ArrayMaxSize / Unsafe.SizeOf<VBuffer<T>>();
 
         private readonly List<List<VBuffer<T>>> _vBuffers = new List<List<VBuffer<T>>>(); // To store more than intMax number of vbuffers
@@ -56,9 +55,7 @@ public VBufferDataFrameColumn(string name, IEnumerable<VBuffer<T>> values) : bas
             }
         }
 
-        private long _nullCount;
-
-        public override long NullCount => _nullCount;
+        public override long NullCount => 0;
 
         protected internal override void Resize(long length)
         {
@@ -94,6 +91,11 @@ private int GetBufferIndexContainingRowIndex(long rowIndex)
         }
 
         protected override object GetValue(long rowIndex)
+        {
+            return GetTypedValue(rowIndex);
+        }
+
+        protected VBuffer<T> GetTypedValue(long rowIndex)
         {
             int bufferIndex = GetBufferIndexContainingRowIndex(rowIndex);
             return _vBuffers[bufferIndex][(int)(rowIndex % MaxCapacity)];
@@ -118,19 +120,13 @@ protected override IReadOnlyList<object> GetValues(long startIndex, int length)
 
         protected override void SetValue(long rowIndex, object value)
         {
-            if (value == null || value is VBuffer<T>)
+            if (value == null)
             {
-                int bufferIndex = GetBufferIndexContainingRowIndex(rowIndex);
-                int bufferOffset = (int)(rowIndex % MaxCapacity);
-                var oldValue = _vBuffers[bufferIndex][bufferOffset];
-                _vBuffers[bufferIndex][bufferOffset] = (VBuffer<T>)value;
-                if (!oldValue.Equals((VBuffer<T>)value))
-                {
-                    if (value == null)
-                        _nullCount++;
-                    if (oldValue.Length == 0 && _nullCount > 0)
-                        _nullCount--;
-                }
+                throw new NotSupportedException("Null values are not supported by VBufferDataFrameColumn");
+            }
+            else if (value is VBuffer<T> vbuffer)
+            {
+                SetTypedValue(rowIndex, vbuffer);
             }
             else
             {
@@ -138,10 +134,16 @@ protected override void SetValue(long rowIndex, object value)
             }
         }
 
+        protected void SetTypedValue(long rowIndex, VBuffer<T> value)
+        {
+            int bufferIndex = GetBufferIndexContainingRowIndex(rowIndex);
+            _vBuffers[bufferIndex][(int)(rowIndex % MaxCapacity)] = value;
+        }
+
         public new VBuffer<T> this[long rowIndex]
         {
-            get => (VBuffer<T>)GetValue(rowIndex);
-            set => SetValue(rowIndex, value);
+            get => GetTypedValue(rowIndex);
+            set => SetTypedValue(rowIndex, value);
         }
 
         /// <summary>