- [https://use-the-index-luke.com/sql/sorting-grouping/order-by-asc-desc-nulls-last](https://use-the-index-luke.com/sql/sorting-grouping/order-by-asc-desc-nulls-last)
- [https://explainextended.com/2009/04/27/descending-indexes/](https://explainextended.com/2009/04/27/descending-indexes/)
- the database uses the index tree to find the last matching entry
- it the follows the leaf node chain “upwards” (which is why the database uses a doubly linked list to build the leaf node chain)

Index column ordering can be read either way by databases