I'm trying to implement an app and am worried about supabase's scalability -- specifically pertaining to inserts, updates, and deletions. What are the practical write rate limits I should expect with a pro account on this platform? or with an enterprise account? For clarification, my concerns stem from the fact that supabase uses postgres, a relational db whereas I understand document based dbs to be generally faster due to ease of horizontal scaling and the nature of eventual consistency.

Well really not a rate limit thing. It is how much CPU and memory/disk you have in your instance. And it all depends on your data complexity. Just as a quick simple test from the supabase-js on a FREE instance. A loop of 1000 10 row bulk inserts (no return of data) to a single table with RLS on from 1 client. The pictures shows the time consumed for the queries in the database. So 1000 queries at 0.2msec each, with each of those doing 10 row bulk insert. The browser took less than 2 seconds (with logs and console.logs for each) to do the 1000 http requests and get positive status. The table already had 100k rows in it also. 10k rows added total. Anyway probably best to do some testing.