I've stumbled upon this ebook today: https://spellbookpress.com/books/temple-of-django-database-performance/
I bought it on a whim, because I had to pinpoint a lot of database performance issue in #Funkwhale lately.
It's shorter than I expected, but I definitely learned some things.
If you're intertested in #Django and #database perf (write efficient queries with/without the ORM, analyze query plans, optimize with defer, only, select_related, prefetch_related, F, Q, subqueries, indexes, etc.) you should probably give it a try.
I can send you my copy if we know each other also :)
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