[nuttingd]

I have read the docs plenty of times, but it never stuck for me until I read the (free!) PostgreSQL 14 Internals ebook: https://postgrespro.com/community/books/internals

Quoted from Page 70:

If you use the Serializable level, it must be observed by all transactions of the application. When combined with other levels, Serializable behaves as Repeatable Read without any notice. So if you decide to use the Serializable level, it makes read sense to modify the default_transaction_isolation parameter value accordingly -- even though someone can still overwrite it by explicitly setting a different level.

I had a real "WTF?" moment when I read this the first time.

[Fire-Dragon-DoL]

Interesting, this book looks really cool!