Interesting, I knew about defer and used it in the past for pretty much the purpose the first example illustrates, but didn't remember/realize it could be used

Interesting, I knew about defer and used it in the past for pretty much the purpose the first example illustrates, but didn't remember/realize it could be used on a per-query basis. I think if you strip columns for performance reasons for one specific query it would still be better to use Bundles or the equivalent loose select (i.e. session.query(Book.id, Book.title)) instead of query-local-deferred columns, because then you will notice if a code change leads to a down-stream access of an unwanted column for some reason.