On Aug 3, 2007, at 10:57 AM, Paul Colomiets wrote:
> > Michael Bayer wrote: >> >> Hmmm, do you mean joining relations against a subrelation that uses >> an aggregate like MAX ? i'd like to see what you have in mind for >> this. > Well, I think I've not explained it correctly. > > It looks quite like you're saying, but I want that aggregations > to be stored (cached?) in the table. > > Suppose you have, a table of articles and comments on them. > I want to have article.last_comment and article.number_of_comments > to be stored in columns and to be updated when I'm saving Comment > object (which e.g. has a foreign key to article). > And I really want that to be atomic updates (update set cnt=cnt+1) > instead of updating counter on Article instance and saving it. we've just added the atomic update thing to 0.4 (note the uppercase Article which produces a column expression): article.comment_count = Article.comment_count + 1 session.flush() i wonder though if theres some way that could get "out of sync" with the actual number. you'd have to be careful to establish this update. if you wanted to use a mapper extension to do it, then youd have to issue the UPDATE directly, the change to the "comment_count" attribute wont get picked up if its established within the flush itself. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
