Inherit settings only if subset of columns is affected in mutation

Avogar · Avogar · commit b4e3dac55695 · 2025-12-17T19:36:31.000Z
diff --git a/src/Storages/MergeTree/MutateTask.cpp b/src/Storages/MergeTree/MutateTask.cpp
@@ -583,10 +583,26 @@ getColumnsForNewDataPart(
         }
     }
 
-    /// We must use serialization info settings from source part, because data files of some
-    /// columns might be copied without actual serialization, so changes in serialization
+    SerializationInfo::Settings settings;
+    /// If mutations doesn't affect all columns we must use serialization info settings from source part,
+    /// because data files of some columns might be copied without actual serialization, so changes in serialization
     /// settings will not be applied for them (for example, new serialization versions for data types).
-    SerializationInfo::Settings settings = serialization_infos.getSettings();
+    if (!affects_all_columns)
+    {
+        settings = serialization_infos.getSettings();
+    }
+    /// Otherwise use fresh settings from storage.
+    else
+    {
+        settings = SerializationInfo::Settings
+        {
+            (*source_part->storage.getSettings())[MergeTreeSetting::ratio_of_defaults_for_sparse_serialization],
+            false,
+            (*source_part->storage.getSettings())[MergeTreeSetting::serialization_info_version],
+            (*source_part->storage.getSettings())[MergeTreeSetting::string_serialization_version],
+            (*source_part->storage.getSettings())[MergeTreeSetting::nullable_serialization_version],
+        };
+    }
 
     SerializationInfoByName new_serialization_infos(settings);
     for (const auto & [name, old_info] : serialization_infos)
