Software Development
More about Django · Module 2 - Models and the ORM in depth

2.5 Killing N+1 queries

22 min
Back to the curriculum

Video coming soon

The recording for this lesson has not been published yet.

What we cover

  • Why the post list suddenly makes 200 queries
  • select_related for ForeignKey and OneToOne
  • prefetch_related and Prefetch objects
  • only, defer and values for narrow queries
  • Meta.indexes and when an index helps
Written notes for this lesson are being prepared. The outline above already shows what the recording will cover.
← 2.4 Custom managers and querysets 2.6 Slugs, timestamps and abstract base models →

After this lesson you will

  • Spot an N+1 query problem in a template loop
  • Fix it with the right prefetching strategy

Module 2

2.1Relations between models 2.2Migrations for real 2.3QuerySets you actually need 2.4Custom managers and querysets 2.5Killing N+1 queries 2.6Slugs, timestamps and abstract base models