ops.py 文件源码

def to_index(self, migration_context=None):
        if self._orig_index is not None:
            return self._orig_index

        schema_obj = schemaobj.SchemaObjects(migration_context)

        # need a dummy column name here since SQLAlchemy
        # 0.7.6 and further raises on Index with no columns
        return schema_obj.index(
            self.index_name, self.table_name, ['x'], schema=self.schema)