On Wed, Mar 23, 2011 at 10:45 AM, Brian Neal <bgn...@gmail.com> wrote: > Sorry, my bad. I've been tweaking things in vain. Here are the correct > EXPLAINS. > > http://dpaste.com/524865/
ok, now it's obvious. the second query (the one with topic__forum__in=forums, right?) is scanning the whole topic table (12Krows). it seems to be guessing that picking a significant fraction of a very small space (5 forums out of 15, right?) wouldn't be so much better using the index. the first query is using the topic->forum key, narrowing the loop to the ~1388 topics of the given forum. now, how to improve this? it seems a little denormalization is in order. i can thing of two different options: A: add a 'last_post_date' field to the topics table, and select only the most recent 10 or so topics. B: add a new post->forum relation, and maybe a (forum,post_date) index -- Javier -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
