How to cache a paginated Django queryset

Question

How do you cache a paginated Django queryset, specifically in a ListView?

I noticed one query was taking a long time to run, so I\'m attempting to cache it. The queryset

Answer 1

The problem turned out to be a combination of factors. Mainly, the result returned by the paginate_queryset() contains a reference to the unlimited queryset, meaning it's essentially uncachable. When I called cache.set(mykey, (paginator, page, object_list, other_pages)), it was trying to serialize thousands of records instead of just the page_size number of records I was expecting, causing the cached item to exceed memcached's limits and fail.

The other factor was the horrible default error reporting in the memcached/python-memcached, which silently hides all errors and turns cache.set() into a nop if anything goes wrong, making it very time-consuming to track down the problem.

I fixed this by essentially rewriting paginate_queryset() to ditch Django's builtin paginator functionality altogether and calculate the queryset myself with:

object_list = queryset[page_size*(page-1):page_size*(page-1)+page_size]

and then caching that object_list.