Key Django QuerySet Tips to Reduce Database Hits and Boost Performance
A developer note originally published in March 2020 outlines practical techniques for optimising Django QuerySet efficiency. Django QuerySets use lazy evaluation, meaning database queries are only executed when the results are explicitly requested. Developers can improve performance by leveraging QuerySet caching with the 'with' template tag, using 'select_related()' and 'prefetch_related()' to minimise redundant database hits, and accessing foreign key values directly rather than fetching entire related objects. The '@cached_property' decorator is recommended for expensive model computations to prevent repeated database lookups. Additionally, using 'queryset.exists()' is advised when only checking for the presence of results, though it should be avoided if the full queryset will be needed later anyway.
