haki

Since at least two people noticed, I would just say that the insert-select-insert approach was added later, after I took some inspiration from Django's implementation of get_or_create.

If you store large jsonb values in the database, storing them out of line may be a good thing - for example, you can query metadata much faster.

Also, worth mentioning that jsonb is only benefitial when you plan on indexing/manipulating the data in the database. Otherwise, using json type may be a better choice (smaller size, stored as text, parsed on demand)

I used excalidraw.com

I'm always looking for new copy tricks. Is "copy" a temporary table? Or a variable...?