Erik Darling makes the donuts:
Okay, deep breath. Deep, deep breath.
Would you believe I still have to fix queries with a bunch of functions in joins and where clauses? Like every day? All day?
Where things get tough is when there’s some third party vendor app where code can’t be changed, but customers have become so fed up with performance that they’re willing to make other changes to help things along.
Read on for an example of one scenario in which reversing an index can help improve performance without touching the code.