diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor.cs
index 2ed07ecfe..ba12933f8 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor.cs
@@ -4,40 +4,23 @@
 // Created by: Alex Yakunin
 // Created:    2010.02.19
 
-using System;
-using System.Diagnostics;
 using Xtensive.Core;
 using Xtensive.Orm.Model;
 
-namespace Xtensive.Orm.Internals
-{
-  internal abstract class FieldAccessor
-  {
-    private FieldInfo fld;
-
-    public FieldInfo Field {
-      get { return fld; }
-      set {
-        if (fld !=null)
-          throw Exceptions.AlreadyInitialized("Field");
-        fld = value;
-      }
-    }
-
-    public object DefaultUntypedValue { get; private set; }
-
-    public abstract bool AreSameValues(object oldValue, object newValue);
+namespace Xtensive.Orm.Internals;
 
-    public abstract void SetUntypedValue(Persistent obj, object value);
-
-    public abstract object GetUntypedValue(Persistent obj);
+internal abstract class FieldAccessor(object defaultUntypedValue)
+{
+  protected ColNum FieldIndex;
 
+  public object DefaultUntypedValue { get; } = defaultUntypedValue;
 
-    // Constructors
-    
-    protected FieldAccessor(object defaultUntypedValue)
-    {
-      DefaultUntypedValue = defaultUntypedValue;
-    }
+  public virtual void SetFieldInfo(FieldInfo value)
+  {
+    FieldIndex = FieldIndex == 0 ? value.MappingInfo.Offset : throw Exceptions.AlreadyInitialized("Field");
   }
+
+  public abstract bool AreSameValues(object oldValue, object newValue);
+  public abstract void SetUntypedValue(Persistent obj, object value);
+  public abstract object GetUntypedValue(Persistent obj);
 }
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessorProvider.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessorProvider.cs
index 63f5d236e..35c2e0a0e 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessorProvider.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessorProvider.cs
@@ -56,8 +56,8 @@ private static FieldAccessor CreateFieldAccessor(Type accessorType, FieldInfo fi
           accessorType.CachedMakeGenericType(field.ValueType),
           BindingFlags.CreateInstance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance,
           null, Array.Empty<object>(), null);
-      accessor.Field = field;
+      accessor.SetFieldInfo(field);
       return accessor;
     }
   }
-}
\ No newline at end of file
+}
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/CachingFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/CachingFieldAccessor.cs
index 91780d522..5953f3bcb 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/CachingFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/CachingFieldAccessor.cs
@@ -4,20 +4,21 @@
 // Created by: Dmitri Maximov
 // Created:    2009.07.08
 
-using System;
+using Xtensive.Core;
 using Xtensive.Orm.Model;
 
-namespace Xtensive.Orm.Internals.FieldAccessors
+namespace Xtensive.Orm.Internals.FieldAccessors;
+
+internal abstract class CachingFieldAccessor<T> : FieldAccessor<T>
 {
-  internal abstract class CachingFieldAccessor<T> : FieldAccessor<T>
-  {
-    public static Func<Persistent, FieldInfo, IFieldValueAdapter> Constructor;
+  public static Func<Persistent, FieldInfo, IFieldValueAdapter> Constructor;
+
+  protected FieldInfo Field;
 
-    public override T GetValue(Persistent obj)
-    {
-      var field = Field;
-      var valueAdapter = obj.GetFieldValueAdapter(field, Constructor);
-      return (T) valueAdapter;
-    }
+  public override void SetFieldInfo(FieldInfo value) {
+    Field = Field is null ? value : throw Exceptions.AlreadyInitialized("Field");
+    base.SetFieldInfo(value);
   }
-}
\ No newline at end of file
+
+  public override T GetValue(Persistent obj) => (T) obj.GetFieldValueAdapter(Field, Constructor);
+}
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/DefaultFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/DefaultFieldAccessor.cs
index 68bcf6982..4640e39f4 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/DefaultFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/DefaultFieldAccessor.cs
@@ -4,7 +4,6 @@
 // Created by: Alexey Gamzov
 // Created:    2008.05.26
 
-using System;
 using Xtensive.Reflection;
 
 namespace Xtensive.Orm.Internals.FieldAccessors
@@ -32,17 +31,11 @@ public override bool AreSameValues(object oldValue, object newValue)
     }
 
     /// <inheritdoc/>
-    public override T GetValue(Persistent obj)
-    {
-      var fieldIndex = Field.MappingInfo.Offset;
-      var tuple = obj.Tuple;
-      var value = tuple.GetValueOrDefault<T>(fieldIndex);
-      return value;
-    }
+    public override T GetValue(Persistent obj) => obj.Tuple.GetValueOrDefault<T>(FieldIndex);
 
     /// <inheritdoc/>
     /// <exception cref="InvalidOperationException">Invalid arguments.</exception>
     public override void SetValue(Persistent obj, T value) =>
-      obj.Tuple.SetValue(Field.MappingInfo.Offset, value);
+      obj.Tuple.SetValue(FieldIndex, value);
   }
 }
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EntityFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EntityFieldAccessor.cs
index 826c8f15c..04f12f68c 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EntityFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EntityFieldAccessor.cs
@@ -4,54 +4,48 @@
 // Created by: Alexey Gamzov
 // Created:    2008.05.26
 
-using System;
-
+using Xtensive.Core;
+using Xtensive.Orm.Model;
 using Xtensive.Tuples;
 
 namespace Xtensive.Orm.Internals.FieldAccessors
 {
   internal class EntityFieldAccessor<T> : FieldAccessor<T>
   {
-    /// <inheritdoc/>
-    public override bool AreSameValues(object oldValue, object newValue)
+    private FieldInfo field;
+
+    public override void SetFieldInfo(FieldInfo value)
     {
-      return ReferenceEquals(oldValue, newValue);
+      field = field is null ? value : throw Exceptions.AlreadyInitialized("Field");
+      base.SetFieldInfo(value);
     }
+
+    /// <inheritdoc/>
+    public override bool AreSameValues(object oldValue, object newValue) => ReferenceEquals(oldValue, newValue);
     /// <inheritdoc/>
     /// <exception cref="InvalidOperationException">Invalid arguments.</exception>
     public override void SetValue(Persistent obj, T value)
     {
-      var entity = value as Entity;
-      var field = Field;
+      var tuple = obj.Tuple;
+      if (value is Entity entity) {
+        if (entity.Session != obj.Session)
+          throw new InvalidOperationException(string.Format(Strings.ExEntityXIsBoundToAnotherSession, entity.Key));
 
-      if (!ReferenceEquals(value, null) && entity==null)
-        throw new InvalidOperationException(string.Format(
-          Strings.ExValueShouldBeXDescendant, WellKnownOrmTypes.Entity));
-
-      if (entity!=null && entity.Session!=obj.Session)
-        throw new InvalidOperationException(string.Format(
-          Strings.ExEntityXIsBoundToAnotherSession, entity.Key)); 
-
-      var mappingInfo = field.MappingInfo;
-      int fieldIndex = mappingInfo.Offset;
-      if (entity==null) {
-        int nextFieldIndex = fieldIndex + mappingInfo.Length;
-        for (int i = fieldIndex; i < nextFieldIndex; i++)
-          obj.Tuple.SetValue(i, null);
+        entity.Key.Value.CopyTo(tuple, 0, FieldIndex, field.MappingInfo.Length);
       }
       else {
-        entity.Key.Value.CopyTo(obj.Tuple, 0, fieldIndex, mappingInfo.Length);
+        if (!ReferenceEquals(value, null))
+          throw new InvalidOperationException(string.Format(Strings.ExValueShouldBeXDescendant, WellKnownOrmTypes.Entity));
+
+        for (int i = FieldIndex, nextFieldIndex = FieldIndex + field.MappingInfo.Length; i < nextFieldIndex; i++)
+          tuple.SetValue(i, null);
       }
     }
 
     /// <inheritdoc/>
-    public override T GetValue(Persistent obj)
-    {
-      var field = Field;
-      Key key = obj.GetReferenceKey(field);
-      if (key is null)
-        return default(T);
-      return (T) (object) obj.Session.Query.SingleOrDefault(key);
-    }
+    public override T GetValue(Persistent obj) =>
+      obj.GetReferenceKey(field) is { } key
+        ? (T) (object) obj.Session.Query.SingleOrDefault(key)
+        : default;
   }
 }
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EnumFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EnumFieldAccessor.cs
index 87d7ecb36..67714be11 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EnumFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/EnumFieldAccessor.cs
@@ -4,7 +4,7 @@
 // Created by: Alexey Gamzov
 // Created:    2008.06.07
 
-using System;
+using Xtensive.Orm.Model;
 using Xtensive.Reflection;
 using Xtensive.Tuples;
 
@@ -18,6 +18,14 @@ internal sealed class EnumFieldAccessor<T> : FieldAccessor<T>
         ? (type.IsNullable() ? null : Enum.GetValues(type).GetValue(0))
         : default(T);
 
+    private Type columnValueType;
+
+    public override void SetFieldInfo(FieldInfo value)
+    {
+      columnValueType = value.Column.ValueType;
+      base.SetFieldInfo(value);
+    }
+
     /// <inheritdoc/>
     public override bool AreSameValues(object oldValue, object newValue)
     {
@@ -27,25 +35,17 @@ public override bool AreSameValues(object oldValue, object newValue)
     /// <inheritdoc/>
     public override T GetValue(Persistent obj)
     {
-      var field = Field;
-      int fieldIndex = field.MappingInfo.Offset;
-      var tuple = obj.Tuple;
-
-      TupleFieldState state;
-      var value = tuple.GetValue(fieldIndex, out state);
-      if (!state.HasValue())
-        return (T) @default;
-      if (type.IsEnum)
-        return (T) Enum.ToObject(type, value);
-      return (T) Enum.ToObject(Nullable.GetUnderlyingType(type), value);
+      var value = obj.Tuple.GetValue(FieldIndex, out var state);
+      return (T) (!state.HasValue() ? @default
+        : type.IsEnum ? Enum.ToObject(type, value)
+        : Enum.ToObject(Nullable.GetUnderlyingType(type), value));
     }
 
     /// <inheritdoc/>
     public override void SetValue(Persistent obj, T value)
     {
-      var field = Field;
       // Biconverter<object, T> converter = GetConverter(field.ValueType);
-      obj.Tuple.SetValue(field.MappingInfo.Offset, value==null ? null : Convert.ChangeType(value, field.Column.ValueType));
+      obj.Tuple.SetValue(FieldIndex, value==null ? null : Convert.ChangeType(value, columnValueType));
     }
   }
-}
\ No newline at end of file
+}
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/KeyFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/KeyFieldAccessor.cs
index 88a89062e..83a39f7a4 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/KeyFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/KeyFieldAccessor.cs
@@ -4,41 +4,27 @@
 // Created by: Alex Yakunin
 // Created:    2008.11.21
 
-using System;
 using Xtensive.Tuples;
-using Tuple = Xtensive.Tuples.Tuple;
 
-namespace Xtensive.Orm.Internals.FieldAccessors
-{
-  internal class KeyFieldAccessor<T> : FieldAccessor<T> 
-  {
-    private static readonly T @default = default;
+namespace Xtensive.Orm.Internals.FieldAccessors;
 
-    /// <inheritdoc/>
-    public override bool AreSameValues(object oldValue, object newValue)
-    {
-      return object.Equals(oldValue, newValue);
-    }
+internal class KeyFieldAccessor<T> : FieldAccessor<T>
+{
+  /// <inheritdoc/>
+  public override bool AreSameValues(object oldValue, object newValue) => Equals(oldValue, newValue);
 
-    /// <inheritdoc/>
-    public override T GetValue(Persistent obj)
-    {
-      var field = Field;
-      int fieldIndex = field.MappingInfo.Offset;
-      var tuple = obj.Tuple;
-      TupleFieldState state;
-      var value = tuple.GetValue<string>(fieldIndex, out state);
-      if (!state.IsAvailable())
-        return @default;
-      return (T) (object) Key.Parse(obj.Session.Domain, value);
-    }
+  /// <inheritdoc/>
+  public override T GetValue(Persistent obj)
+  {
+    var value = obj.Tuple.GetValue<string>(FieldIndex, out var state);
+    return !state.IsAvailable()
+      ? default
+      : (T) (object) Key.Parse(obj.Session.Domain, value);
+  }
 
-    /// <inheritdoc/>
-    public override void SetValue(Persistent obj, T value)
-    {
-      var field = Field;
-      var key = (Key) (object) value;
-      obj.Tuple.SetValue(field.MappingInfo.Offset, key is null ? null : key.Format());
-    }
+  /// <inheritdoc/>
+  public override void SetValue(Persistent obj, T value)
+  {
+    obj.Tuple.SetValue(FieldIndex, ((Key) (object) value)?.Format());
   }
 }
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/StructureFieldAccessor.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/StructureFieldAccessor.cs
index 5b0ff92ec..648fbac9f 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/StructureFieldAccessor.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessors/StructureFieldAccessor.cs
@@ -4,9 +4,6 @@
 // Created by: Dmitri Maximov
 // Created:    2008.05.30
 
-using System;
-using Xtensive.Core;
-
 using Xtensive.Tuples;
 
 namespace Xtensive.Orm.Internals.FieldAccessors
@@ -14,25 +11,21 @@ namespace Xtensive.Orm.Internals.FieldAccessors
   internal sealed class StructureFieldAccessor<T> : CachingFieldAccessor<T>
   {
     /// <inheritdoc/>
-    public override bool AreSameValues(object oldValue, object newValue)
-    {
-      return oldValue.Equals(newValue);
-    }
+    public override bool AreSameValues(object oldValue, object newValue) => oldValue.Equals(newValue);
+
     /// <inheritdoc/>
     public override void SetValue(Persistent obj, T value)
     {
-      var field = Field;
       ArgumentNullException.ThrowIfNull(value);
       var valueType = value.GetType();
-      if (field.ValueType != valueType)
+      if (Field.ValueType != valueType)
         throw new InvalidOperationException(String.Format(
-          Strings.ExResultTypeIncorrect, valueType.Name, field.ValueType.Name));
+          Strings.ExResultTypeIncorrect, valueType.Name, Field.ValueType.Name));
 
       var structure = (Structure) (object) value;
       var adapter = (IFieldValueAdapter)value;
-      if (adapter.Owner!=null)
-        adapter.Owner.EnsureIsFetched(adapter.Field);
-      structure.Tuple.CopyTo(obj.Tuple, 0, field.MappingInfo.Offset, field.MappingInfo.Length);
+      adapter.Owner?.EnsureIsFetched(adapter.Field);
+      structure.Tuple.CopyTo(obj.Tuple, 0, FieldIndex, Field.MappingInfo.Length);
     }
 
     // Type initializer
@@ -42,4 +35,4 @@ static StructureFieldAccessor()
        Constructor = (obj, field) => Activator.CreateStructure(field.ValueType, obj, field);
     }
   }
-}
\ No newline at end of file
+}
diff --git a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor{T}.cs b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor{T}.cs
index 4c83a9b52..afa9722ab 100644
--- a/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor{T}.cs
+++ b/Orm/Xtensive.Orm/Orm/Internals/FieldAccessor{T}.cs
@@ -4,37 +4,13 @@
 // Created by: Alexey Gamzov
 // Created:    2008.06.02
 
-using System;
-using Xtensive.Orm.Model;
+namespace Xtensive.Orm.Internals;
 
-
-namespace Xtensive.Orm.Internals
+internal abstract class FieldAccessor<T>() : FieldAccessor(default(T))
 {
-  internal abstract class FieldAccessor<T> : FieldAccessor
-  {
-    public T DefaultValue { get; private set; }
-
-    public abstract void SetValue(Persistent obj, T value);
-
-    public abstract T GetValue(Persistent obj);
-
-    public override void SetUntypedValue(Persistent obj, object value)
-    {
-      SetValue(obj, (T) value);
-    }
-
-    public override object GetUntypedValue(Persistent obj)
-    {
-      return GetValue(obj);
-    }
-
+  public abstract void SetValue(Persistent obj, T value);
+  public override void SetUntypedValue(Persistent obj, object value) => SetValue(obj, (T) value);
 
-    // Constructors
-    
-    protected FieldAccessor()
-      : base(default(T))
-    {
-      DefaultValue = default(T);
-    }
-  }
-}
\ No newline at end of file
+  public abstract T GetValue(Persistent obj);
+  public override object GetUntypedValue(Persistent obj) => GetValue(obj);
+}