DatabasesIntermediate
N+1 Query Problem
PronunciationEN plus WUN
Definition
A performance bug: one query loads a list of N items, then the code runs one extra query for each item, so you get N+1 queries.
Where you hear it
ORM performance reviews and slow-page investigations.
Examples
The page runs 101 queries because of an N+1 problem.
Use
select_relatedto load the related data in one query.
Common mistake
Testing only with 5 rows. The problem appears only with thousands of rows in production.