I love the SQL trigger idea, that would be the best. Let the db maintain integrity.
I have yet to have any out of sync issues with after_... calls doing counter cache like functionality, but I suppose it could happen. Nathan On Apr 6, 7:34 am, Yehuda Katz <[email protected]> wrote: > It might be interesting to use Merb's run_later facilities to asynchronously > update the counter cache on a periodic basis (or only if something was added > to a queue). > > However, it feels like the BEST option would be to add a standard database > trigger and let the database handle it without the potential for problems. > Perhaps this is a case for supporting arbitrary options and letting the > adapters generate the appropriate SQL. So: > > has n, :posts, :counter_cache => true > > and automigrate would generate the appropriate SQL for the trigger for each > supported DB. What do you think? > > -- Yehuda > > 2009/4/5 Jacques Crocker <[email protected]> > > > > > > > > > There's no reason to ever change a counter_cache after_save. You need > > a combination of several hooks (after_create, after_delete, etc). > > Having it abstracted seems greatly preferred. Even with these hooks, > > the count would often go out of sync so I had an update_cache method > > that would synchronize everything, running once in a while. And all > > this logic duplicated for each has n relationship. > > > Even with this plugin, I still run into the issue that the delete > > method on an association isnt implemented in Datamapper 0.9.11. So > > running "user.posts.delete" returns the message "NotImplementedError: > > destroy *with* validations has not be written yet, try destroy!". So > > its likely I'll still need these synchronization methods that keep the > > counters in sync after certain operations. > > > On Apr 5, 3:58 am, Yehuda Katz <[email protected]> wrote: > > > Why is a counter cache harder than a simple after_save hook. Having never > > > actually attempted to roll my own, I'm curious about what specifically is > > > difficult. > > > > -- Yehuda > > > > 2009/4/5 Jacques Crocker <[email protected]> > > > > > If you're in need of counter caches in Datamapper, I found a pretty > > > > nice plugin that is working great for me so far. > > > >http://github.com/saimonmoore/dm-counter-cache > > > > > Maybe I'm crazy, but can't imagine anyone writing a moderate sized web > > > > app and not needing counter caches. Any summary list page is going to > > > > cause an N+1 craziness of count(*) queries. Rolling your own just a > > > > complete mess (thats what I did before I found this plugin). > > > > > We need to get this into dm-more. The plugin is well spec'ed. Maybe we > > > > should tweak the interface, I'm not sure. Dan, can you take a look and > > > > see if its to your liking? > > > > > This is a followup to the thread: > > > > >http://groups.google.com/group/datamapper/browse_thread/thread/95d21c. > > .. > > > > > Thanks > > > > -- > > > Yehuda Katz > > > Developer | Engine Yard > > > (ph) 718.877.1325 > > -- > Yehuda Katz > Developer | Engine Yard > (ph) 718.877.1325 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "DataMapper" 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/datamapper?hl=en -~----------~----~----~----~------~----~------~--~---
