feat: support add sub-column to struct col

python/python/tests/test_dataset.py

@@ -2501,10 +2501,14 @@ def test_add_null_columns_with_conflict_names(tmp_path: Path):
     assert len(fragments) == 1
     assert len(fragments[0].data_files()) == 1
 
-    with pytest.raises(Exception, match=".*Column id already exists in the dataset.*"):
+    with pytest.raises(
+        Exception, match=".*Type conflicts between id\\(Int64\\) and id\\(Float32\\).*"
+    ):
         ds.add_columns(pa.field("id", pa.float32()))
 
-    with pytest.raises(Exception, match=".*Column id already exists in the dataset.*"):
+    with pytest.raises(
+        Exception, match=".*Type conflicts between id\\(Int64\\) and id\\(Float32\\).*"
+    ):
         ds.add_columns([pa.field("id", pa.float32()), pa.field("good", pa.int32())])
 
 

rust/lance-encoding/src/version.rs

@@ -81,6 +81,10 @@ impl LanceFileVersion {
 
         Self::iter().filter(|&v| v != Self::Stable && v != Self::Next && v != Self::Legacy)
     }
+
+    pub fn support_add_sub_column(&self) -> bool {
+        self > &Self::V2_1
+    }
 }
 
 impl std::fmt::Display for LanceFileVersion {