How to confirm that the index you added actually improves query performance
Database indexes allow us to speed up queries by providing a method to quickly look up data. However, do we always check that they actually improve performance? In this talk, I explain how and why an automatically added database index did not get used by the queries we expected. Together we will go through SQL produced from Django ORM, index structures and generating database query plans to unravel what was actually going on behind the scenes in our queries.