Rename ensure_lineage_table to create_lineage_table

Also:
- Remove redundant U check for second operand in assert_join_compatibility
- Suggest .join(semantic_check=False) in error message for non-homologous namesakes

Author: claude

src/datajoint/condition.py

@@ -115,7 +115,7 @@ def assert_join_compatibility(expr1, expr2):
             raise DataJointError("Object %r is not a QueryExpression and cannot be joined." % rel)
 
     # dj.U is always compatible - it contains all possible lineages
-    if isinstance(expr1, U) or isinstance(expr2, U):
+    if isinstance(expr1, U):
         return
 
     # Find namesake attributes (same name in both expressions)
@@ -130,7 +130,8 @@ def assert_join_compatibility(expr1, expr2):
             raise DataJointError(
                 f"Cannot join on attribute `{name}`: different lineages "
                 f"({lineage1} vs {lineage2}). "
-                f"Use .proj() to rename one of the attributes."
+                f"Use .proj() to rename one of the attributes or "
+                f".join(semantic_check=False) to force a natural join."
             )
 
 

src/datajoint/lineage.py

@@ -19,7 +19,7 @@
 LINEAGE_TABLE_NAME = "~lineage"
 
 
-def ensure_lineage_table(connection, database):
+def create_lineage_table(connection, database):
     """Create the ~lineage table if it doesn't exist."""
     connection.query(
         f"""
@@ -100,7 +100,7 @@ def insert_lineage_entries(connection, database, entries):
     if not entries:
         return
 
-    ensure_lineage_table(connection, database)
+    create_lineage_table(connection, database)
 
     for table_name, attribute_name, lineage in entries:
         connection.query(