diff --git a/RocksDbSharp/ColumnFamilyOptions.cs b/RocksDbSharp/ColumnFamilyOptions.cs
index 4be9690..f2ca999 100644
--- a/RocksDbSharp/ColumnFamilyOptions.cs
+++ b/RocksDbSharp/ColumnFamilyOptions.cs
@@ -298,16 +298,16 @@ private static MergeOperator GetMergeOperatorFromPtr(IntPtr getMergeOperatorPtr)
             return getMergeOperator();
         }
 
-        private unsafe static IntPtr MergeOperator_PartialMerge(IntPtr state, IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength)
+        private unsafe static IntPtr MergeOperator_PartialMerge(IntPtr state, IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength)
         {
             var mergeOperator = GetMergeOperatorFromPtr((*((MergeOperatorState*)state)).GetMergeOperatorPtr);
-            return mergeOperator.PartialMerge(key, keyLength, operandsList, operandsListLength, numOperands, success, newValueLength);
+            return mergeOperator.PartialMerge(key, keyLength, operandsList, operandsListLength, numOperands, out success, out newValueLength);
         }
 
-        private unsafe static IntPtr MergeOperator_FullMerge(IntPtr state, IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength)
+        private unsafe static IntPtr MergeOperator_FullMerge(IntPtr state, IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength)
         {
             var mergeOperator = GetMergeOperatorFromPtr((*((MergeOperatorState*)state)).GetMergeOperatorPtr);
-            return mergeOperator.FullMerge(key, keyLength, existingValue, existingValueLength, operandsList, operandsListLength, numOperands, success, newValueLength);
+            return mergeOperator.FullMerge(key, keyLength, existingValue, existingValueLength, operandsList, operandsListLength, numOperands, out success, out newValueLength);
         }
 
         private unsafe static void MergeOperator_DeleteValue(IntPtr state, IntPtr value, UIntPtr valueLength)
diff --git a/RocksDbSharp/MergeOperator.cs b/RocksDbSharp/MergeOperator.cs
index 19a9261..f1ac495 100644
--- a/RocksDbSharp/MergeOperator.cs
+++ b/RocksDbSharp/MergeOperator.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using System.Text;
 
 namespace RocksDbSharp
@@ -7,8 +8,8 @@ namespace RocksDbSharp
     public interface MergeOperator
     {
         string Name { get; }
-        IntPtr PartialMerge(IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength);
-        IntPtr FullMerge(IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength);
+        IntPtr PartialMerge(IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength);
+        IntPtr FullMerge(IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength);
         void DeleteValue(IntPtr value, UIntPtr valueLength);
     }
 
@@ -22,38 +23,28 @@ public static class MergeOperators
         /// This is called to combine two-merge operands (if possible)
         /// </summary>
         /// <param name="key">The key that's associated with this merge operation</param>
-        /// <param name="keyLength"></param>
-        /// <param name="operandsList">the sequence of merge operations to apply, front() first</param>
-        /// <param name="operandsListLength"></param>
-        /// <param name="numOperands"></param>
+        /// <param name="operands">the sequence of merge operations to apply, front() first</param>
         /// <param name="success">Client is responsible for filling the merge result here</param>
-        /// <param name="newValueLength"></param>
         /// <returns></returns>
-        public delegate IntPtr PartialMergeFunc(IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength);
+        public delegate byte[] PartialMergeFunc(byte[] key, byte[][] operands, out bool success);
+
         /// <summary>
         /// Gives the client a way to express the read -> modify -> write semantics.
         /// Called when a Put/Delete is the *existing_value (or nullptr)
         /// </summary>
         /// <param name="key">The key that's associated with this merge operation.</param>
-        /// <param name="keyLength"></param>
         /// <param name="existingValue">null indicates that the key does not exist before this op</param>
-        /// <param name="existingValueLength"></param>
-        /// <param name="operandsList">the sequence of merge operations to apply, front() first.</param>
-        /// <param name="operandsListLength"></param>
-        /// <param name="numOperands"></param>
+        /// <param name="operands">the sequence of merge operations to apply, front() first.</param>
         /// <param name="success">Client is responsible for filling the merge result here</param>
-        /// <param name="newValueLength"></param>
         /// <returns></returns>
-        public delegate IntPtr FullMergeFunc(IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength);
-        public delegate void DeleteValueFunc(IntPtr value, UIntPtr valueLength);
+        public delegate byte[] FullMergeFunc(byte[] key, byte[] existingValue, byte[][] operands, out bool success);
 
         public static MergeOperator Create(
             string name,
             PartialMergeFunc partialMerge,
-            FullMergeFunc fullMerge,
-            DeleteValueFunc deleteValue)
+            FullMergeFunc fullMerge)
         {
-            return new MergeOperatorImpl(name, partialMerge, fullMerge, deleteValue);
+            return new MergeOperatorImpl(name, partialMerge, fullMerge);
         }
 
         private class MergeOperatorImpl : MergeOperator
@@ -61,24 +52,83 @@ private class MergeOperatorImpl : MergeOperator
             public string Name { get; }
             private PartialMergeFunc PartialMerge { get; }
             private FullMergeFunc FullMerge { get; }
-            private DeleteValueFunc DeleteValue { get; }
 
-            public MergeOperatorImpl(string name, PartialMergeFunc partialMerge, FullMergeFunc fullMerge, DeleteValueFunc deleteValue)
+            public MergeOperatorImpl(string name, PartialMergeFunc partialMerge, FullMergeFunc fullMerge)
             {
                 Name = name;
                 PartialMerge = partialMerge;
                 FullMerge = fullMerge;
-                DeleteValue = deleteValue;
             }
 
-            IntPtr MergeOperator.PartialMerge(IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength)
-                => PartialMerge(key, keyLength, operandsList, operandsListLength, numOperands, success, newValueLength);
+            IntPtr MergeOperator.PartialMerge(IntPtr key, UIntPtr keyLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength)
+            {
+                var _key = new byte[(uint)keyLength];
+                Marshal.Copy(key, _key, 0, _key.Length);
+
+                var _operandsList = new IntPtr[numOperands];
+                Marshal.Copy(operandsList, _operandsList, 0, _operandsList.Length);
+
+                var _operandsListLength = new long[numOperands];
+                Marshal.Copy(operandsListLength, _operandsListLength, 0, _operandsListLength.Length);
+
+                var operands = new byte[numOperands][];
+                for (int i = 0; i < numOperands; i++)
+                {
+                    var operand = new byte[_operandsListLength[i]];
+                    Marshal.Copy(_operandsList[i], operand, 0, operand.Length);
+                    operands[i] = operand;
+                }
+
+                var value = PartialMerge(_key, operands, out var _success);
 
-            IntPtr MergeOperator.FullMerge(IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, IntPtr success, IntPtr newValueLength)
-                => FullMerge(key, keyLength, existingValue, existingValueLength, operandsList, operandsListLength, numOperands, success, newValueLength);
+                var ret = Marshal.AllocHGlobal(value.Length);
+                Marshal.Copy(value, 0, ret, value.Length);
+                newValueLength = (IntPtr)value.Length;
+
+                success = (IntPtr)Convert.ToInt32(_success);
+
+                return ret;
+            }
+
+            IntPtr MergeOperator.FullMerge(IntPtr key, UIntPtr keyLength, IntPtr existingValue, UIntPtr existingValueLength, IntPtr operandsList, IntPtr operandsListLength, int numOperands, out IntPtr success, out IntPtr newValueLength)
+            {
+                var _key = new byte[(uint)keyLength];
+                Marshal.Copy(key, _key, 0, _key.Length);
+
+                byte[] _existingValue = null;
+                if (existingValue != IntPtr.Zero)
+                {
+                    _existingValue = new byte[(uint)existingValueLength];
+                    Marshal.Copy(existingValue, _existingValue, 0, _existingValue.Length);
+                }
+
+                var _operandsList = new IntPtr[numOperands];
+                Marshal.Copy(operandsList, _operandsList, 0, _operandsList.Length);
+
+                var _operandsListLength = new long[numOperands];
+                Marshal.Copy(operandsListLength, _operandsListLength, 0, _operandsListLength.Length);
+
+                var operands = new byte[numOperands][];
+
+                for (int i = 0; i < numOperands; i++)
+                {
+                    var operand = new byte[_operandsListLength[i]];
+                    Marshal.Copy(_operandsList[i], operand, 0, operand.Length);
+                    operands[i] = operand;
+                }
+
+                var value = FullMerge(_key, _existingValue, operands, out var _success);
+
+                var ret = Marshal.AllocHGlobal(value.Length);
+                Marshal.Copy(value, 0, ret, value.Length);
+                newValueLength = (IntPtr)value.Length;
+
+                success = (IntPtr)Convert.ToInt32(_success);
+
+                return ret;
+            }
 
-            void MergeOperator.DeleteValue(IntPtr value, UIntPtr valueLength)
-                => DeleteValue(value, valueLength);
+            void MergeOperator.DeleteValue(IntPtr value, UIntPtr valueLength) => Marshal.FreeHGlobal(value);
         }
     }
-}
+}
\ No newline at end of file
diff --git a/RocksDbSharp/Native.cs b/RocksDbSharp/Native.cs
index 22034bd..d7e72b5 100644
--- a/RocksDbSharp/Native.cs
+++ b/RocksDbSharp/Native.cs
@@ -107,8 +107,8 @@ namespace RocksDbSharp
     public delegate char_ptr CreateFilterDelegate(void_ptr p0, const_char_ptr_const_ptr key_array, const_size_t_ptr key_length_array, int num_keys, size_t_ptr filter_length);
     public delegate char KeyMayMatchDelegate(void_ptr p0, const_char_ptr key, size_t length, const_char_ptr filter, size_t filter_length);
     public delegate void DeleteFilterDelegate(void_ptr p0, const_char_ptr filter, size_t filter_length);
-    public delegate char_ptr FullMergeDelegate(void_ptr p0, const_char_ptr key, size_t key_length, const_char_ptr existing_value, size_t existing_value_length, const_char_ptr_const_ptr operands_list, const_size_t_ptr operands_list_length, int num_operands, unsigned_char_ptr success, size_t_ptr new_value_length);
-    public delegate char_ptr PartialMergeDelegate(void_ptr p0, const_char_ptr key, size_t key_length, const_char_ptr_const_ptr operands_list, const_size_t_ptr operands_list_length, int num_operands, unsigned_char_ptr success, size_t_ptr new_value_length);
+    public delegate char_ptr FullMergeDelegate(void_ptr p0, const_char_ptr key, size_t key_length, const_char_ptr existing_value, size_t existing_value_length, const_char_ptr_const_ptr operands_list, const_size_t_ptr operands_list_length, int num_operands, out unsigned_char_ptr success, out size_t_ptr new_value_length);
+    public delegate char_ptr PartialMergeDelegate(void_ptr p0, const_char_ptr key, size_t key_length, const_char_ptr_const_ptr operands_list, const_size_t_ptr operands_list_length, int num_operands, out unsigned_char_ptr success, out size_t_ptr new_value_length);
     public delegate void DeleteValueDelegate(void_ptr p0, const_char_ptr value, size_t value_length);
     public delegate char_ptr TransformDelegate(void_ptr p0, const_char_ptr key, size_t length, size_t_ptr dst_length);
     public delegate char InDomainDelegate(void_ptr p0, const_char_ptr key, size_t length);
diff --git a/tests/RocksDbSharpTest/FunctionalTests.cs b/tests/RocksDbSharpTest/FunctionalTests.cs
index d90568e..1d78176 100644
--- a/tests/RocksDbSharpTest/FunctionalTests.cs
+++ b/tests/RocksDbSharpTest/FunctionalTests.cs
@@ -429,9 +429,8 @@ public void FunctionalTest()
                   .SetCreateIfMissing(true)
                   .SetMergeOperator(MergeOperators.Create(
                       name: "test-merge-operator",
-                      partialMerge: (key, keyLength, operandsList, operandsListLength, numOperands, success, newValueLength) => IntPtr.Zero,
-                      fullMerge: (key, keyLength, existingValue, existingValueLength, operandsList, operandsListLength, numOperands, success, newValueLength) => IntPtr.Zero,
-                      deleteValue: (value, valueLength) => { }
+                      partialMerge: PartialMerge,
+                      fullMerge: FullMerge
                   ));
                 GC.Collect();
                 using (var db = RocksDbSharp.RocksDb.Open(optsTest, dbname))
@@ -474,5 +473,19 @@ class IntegerStringComparator : StringComparatorBase
             public override int Compare(string a, string b)
                 => Comparer(long.TryParse(a, out long avalue) ? avalue : 0, long.TryParse(b, out long bvalue) ? bvalue : 0);
         }
+
+        private static byte[] PartialMerge(byte[] key, byte[][] operands, out bool success)
+        {
+            success = true;
+
+            return operands[operands.Length - 1];
+        }
+
+        private static byte[] FullMerge(byte[] key, byte[] existingValue, byte[][] operands, out bool success)
+        {
+            success = true;
+
+            return operands[operands.Length - 1];
+        }
     }
 }