Fix: Make sure we never use actual physical names of external tables when evaluating snapshots

Author: izeigerman

sqlmesh/core/snapshot/definition.py

@@ -223,9 +223,6 @@ def _table_name(self, version: str, is_dev: bool, for_read: bool) -> str:
             is_dev: Whether the table name will be used in development mode.
             for_read: Whether the table name will be used for reading by a different snapshot.
         """
-        if self.is_external:
-            return self.name
-
         if is_dev and for_read:
             # If this snapshot is used for **reading**, return a temporary table
             # only if this snapshot captures a direct forward-only change applied to its model.

sqlmesh/core/snapshot/evaluator.py

@@ -470,6 +470,11 @@ def _cleanup_snapshot(self, snapshot: SnapshotInfoLike) -> None:
             table_names.append(snapshot.table_name(is_dev=True))
 
         for table_name in table_names:
+            if not table_name.startswith(snapshot.physical_schema):
+                raise SQLMeshError(
+                    f"Table '{table_name}' is not a part of the physical schema '{snapshot.physical_schema}' and so can't be dropped."
+                )
+
             if snapshot.is_materialized:
                 self.adapter.drop_table(table_name)
                 logger.info("Dropped table '%s'", table_name)

tests/core/test_schema_loader.py

@@ -71,7 +71,6 @@ def test_create_external_models(sushi_context, assert_exp_eq):
 
     snapshot = sushi_context.snapshots["sushi.raw_fruits"]
     snapshot.categorize_as(SnapshotChangeCategory.BREAKING)
-    assert snapshot.table_name() == "sushi.raw_fruits"
 
     fruits = sushi_context.models["sushi.fruits"]
     assert not fruits.kind.is_symbolic