Note
If you don’t understand, you can pretend it’s magic.
It’s a lot of Django reverse engineering combined with a strong test suite. Such a test suite is crucial for a reverse engineering project. If some important part of Django changes and breaks the expected behaviour, you can be sure that the test suite will fail.
Django-cachalot modifies Django in place during execution to add a caching tool just before SQL queries are executed. When a SQL query reads data, we save the result in cache. If that same query is executed later, we fetch that result from cache. When we detect INSERT, UPDATE or DELETE, we know which tables are modified. All the previous cached queries can therefore be safely invalidated.