Advisory locks can be taken at the session (i.e. outside/across transactions) level, and need not be tied to a database object (if you need to operate on multip

Advisory locks can be taken at the session (i.e. outside/across transactions) level, and need not be tied to a database object (if you need to operate on multiple objects, which one are you going to lock?). Simpler cases are supported by e.g. SELECT FOR UPDATE