Janzert schrieb: > I've attached my test project and scripts to the trac issue* if > someone wants to double check my methods.
I'm using the following add-on, maybe it's useful for you, too ;-) https://addons.mozilla.org/en-US/thunderbird/addon/5759 > As you can see the current method of iterating through the groups is > actually 130 to 150 times faster than single query methods. I think this is because the current method uses the group.permissions lists in the database session if possible. I.e. if you run it in a loop, it will become very efficient. However, in reality this function will be called only once or a few times per request, always in a fresh session. You can simulate this with turbogears.database.session.expire_all(). Doing so, I measured that the join method is about 3 times faster and the exists method is about 2 times faster than the old method (similar for both SQLite and Postgres 8.3). So it depends on how people use the permissions attribute. If used more than 2 times per request, the old method is faster. One solution for getting good performance in both cases is using the join method and caching the permissions in the User instance: def permissions(self): try: p = User._permissions except AttributeError: p = set(Permission.query.distinct().join(['groups', 'users']).filter_by(user_id=self.user_id)) User._permissions = p return p Another interesting question is why the join method is in fact faster than the exists method, though you would expect the opposite. See also: http://wrschneider.blogspot.com/2004/12/postgresql-performance-of-where-exists.html In this case we have a chained exists, maybe this makes it difficult to optimize for the database. -- Christoph --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "TurboGears" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/turbogears?hl=en -~----------~----~----~----~------~----~------~--~---
