Hi Richard, Like you've seen, the _number_ of queries often has a large effect on speed.
Also, try comparing your page load time with and without debug toolbar enabled. I found that DDT is slow itself :). Collin On Monday, January 5, 2015 at 10:19:44 AM UTC-5, Richard Brockie wrote: > > Hi Jani, > > That's a correct diagnosis. I knew Django was doing lazy loading, but > didn't fully understand the implications. > > In my case I have a filtered and ordered queryset resulting in ~400 > records. Upon processing in the template, each was prompting a database > visit 3 times when outputting information: hence the ~1200 trips to the > database. > > I've added prefetch_related specifying the related models I'm working with > in the template. > > My 'slow' case has now become: 46 queries in 39 ms, Time: 506 ms: a factor > of 20 speed improvement. > > Thanks for the suggestion! > R. > > On Sunday, January 4, 2015 10:09:58 PM UTC-8, Jani Tiainen wrote: > >> By judging amount of queries of your "slow" page you probably have >> model(s) with foreign keys that you lazy load - which means that each fk is >> loaded individually from the database with separate query. >> >> For example if you have a model that contains 4 foreign keys and you >> query 100 instances (rows) you would actually invoke 1 + 4 * n queries, >> which in example case would be 401. >> >> Without actually knowning your code one of the first options you usually >> do to optimize queries is to use select_related and prefetch_related >> queryset methods to cut down number of queries needed. >> >> -- >> >> Jani Tiainen >> > -- 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/eb15e0ab-2f12-42c1-8971-84f3361368be%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
