diff --git a/src/Common/SettingsChanges.cpp b/src/Common/SettingsChanges.cpp
index 52ab23dde9e..0cfa6804e02 100644
--- a/src/Common/SettingsChanges.cpp
+++ b/src/Common/SettingsChanges.cpp
@@ -36,9 +36,31 @@ String SettingChange::getValueString() const
     return convertFieldToString(field_value);
 }
 
-void SettingChange::throwIfASTValue() const
+const Field & SettingChange::getFieldValue() const
 {
-    if (getASTValue() != nullptr)
+    throwIfASTValueNotConvertedToField();
+    return field_value;
+}
+
+Field & SettingChange::getFieldValue()
+{
+    throwIfASTValueNotConvertedToField();
+    return field_value;
+}
+
+void SettingChange::setFieldValue(const Field & field)
+{
+    field_value = field;
+}
+
+void SettingChange::setASTValue(const ASTPtr & ast)
+{
+    ast_value = ast ? ast->clone() : ast;
+}
+
+void SettingChange::throwIfASTValueNotConvertedToField() const
+{
+    if (getASTValue() != nullptr && field_value == Field{})
         throw Exception(
             ErrorCodes::LOGICAL_ERROR,
             "AST value of the setting must be converted to Field value");
diff --git a/src/Common/SettingsChanges.h b/src/Common/SettingsChanges.h
index e83a7b7a695..d0d72fd725c 100644
--- a/src/Common/SettingsChanges.h
+++ b/src/Common/SettingsChanges.h
@@ -30,19 +30,19 @@ public:
 
     friend bool operator !=(const SettingChange & lhs, const SettingChange & rhs) { return !(lhs == rhs); }
 
-    void throwIfASTValue() const;
+    void throwIfASTValueNotConvertedToField() const;
 
     const String & getName() const { return name; }
     String & getName() { return name; }
 
-    const Field & getFieldValue() const { throwIfASTValue(); return field_value; }
-    Field & getFieldValue() { throwIfASTValue(); return field_value; }
+    const Field & getFieldValue() const;
+    Field & getFieldValue();
 
     const ASTPtr & getASTValue() const { return ast_value; }
     ASTPtr & getASTValue() { return ast_value; }
 
-    void setFieldValue(const Field & field) { field_value = field; }
-    void setASTValue(const ASTPtr & ast) { ast_value = ast->clone(); }
+    void setFieldValue(const Field & field);
+    void setASTValue(const ASTPtr & ast);
 
     String getValueString() const;
 };
diff --git a/src/Storages/MergeTree/registerStorageMergeTree.cpp b/src/Storages/MergeTree/registerStorageMergeTree.cpp
index 94cd3ddf872..83076851b43 100644
--- a/src/Storages/MergeTree/registerStorageMergeTree.cpp
+++ b/src/Storages/MergeTree/registerStorageMergeTree.cpp
@@ -616,7 +616,6 @@ static StoragePtr create(const StorageFactory::Arguments & args)
                     const auto & ast_value = assert_cast<const ASTFunction &>(*change.getASTValue());
                     auto value = createDiskFromDiskAST(ast_value, context);
                     change.setFieldValue(value);
-                    change.setASTValue(nullptr);
                     break;
                 }
             }