Hi David, *select_related* does a JOIN under the hood, and you can't do cross-database joins in the databases supported by Django. For prefetch_related, there is no way out of the box to perform a cross-database join in Python (which is what prefetch_related is doing) but perhaps there is some way to programatically make that happen. I haven't put any effort into exploring that idea.
Thanks, On Thu, May 21, 2015 at 3:42 PM, David <[email protected]> wrote: > Dear List, > > I came about conflicting information (to my mind) concerning the use of > select_related() and prefetch_related(). > My question is whether you can combine select_related() and > prefetch_related() with sharding techniques. If so, how are you doing it? > > Background: > I was watching various videos on Django under load and Django scaling, > generally there comes a point at which they point at database sharding. > Ash Christopher (https://www.youtube.com/watch?v=frlsGUHYu04) points out > that as you use multiple databases with your Application, > select_related() and prefetch_related() can no longer be used. In > Christophe Pettus' videos I have not found such a comment, in fact > select_related() and prefetch_related() seem to be habitually > recommended to speed database connections up. > > Thanks for your insights! > > David > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAJdxA4uqMB_-ovXehbiUnqaX6Co6LP7LPMKAf88fb-Zb6VW_%2BQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
