Fix: Improve the change categorization results by pre-matching root AST nodes (#831)

Author: izeigerman

sqlmesh/core/model/definition.py

@@ -674,7 +674,12 @@ def is_breaking_change(self, previous: Model) -> t.Optional[bool]:
         if not isinstance(previous, SqlModel):
             return None
 
-        edits = ChangeDistiller(t=0.5).diff(previous.render_query(), self.render_query())
+        previous_query = previous.render_query()
+        this_query = self.render_query()
+
+        edits = ChangeDistiller(t=0.5).diff(
+            previous_query, this_query, matchings=[(previous_query, this_query)]
+        )
         inserted_expressions = {e.expression for e in edits if isinstance(e, Insert)}
 
         for edit in edits:

tests/core/test_snapshot.py

@@ -540,7 +540,11 @@ def test_categorize_change_sql(make_snapshot):
     # A complex projection has been added.
     assert (
         categorize_change(
-            new=make_snapshot(SqlModel(name="a", query=parse_one("select 1, fun(a * 2)::INT, ds"))),
+            new=make_snapshot(
+                SqlModel(
+                    name="a", query=parse_one("select 1, fun(another_fun(a + 1) * 2)::INT, ds")
+                )
+            ),
             old=old_snapshot,
             config=config,
         )