That is a good example, but don't forget your DB will also be doing many other things besides managing jobs.

In the Rails world of using the DB for everything you have your primary DB, solid queue, solid cache and solid cable.

If you lean into modern Rails features (using Turbo Streams which involves jobs, async destroying dependents, etc.) it doesn't seem that hard to rack up a lot of DB activity.

Combine this with pretty spotty SSD I/O performance for most VPS servers, I don't know about hosting everything on 1 box on a $20-40 / month server but I feel very comfortable doing that with Redis backing queue + cache + cable while PG focuses as being a primary DB. I haven't seen any success stories yet of anyone using the DB for everything on an entry level VPS. It's mainly DHH mentioning it works great with splitting things into different databases and running it on massive dedicated hardware systems with the best SSDs you can buy.

I like the idea on paper but I don't think I'll switch away from Redis until I see a bunch of social proof of people showing how they are using all of these DB backed tools on a VPS to serve a reasonable amount of traffic. We have 10+ years of proof that Redis works great in these cases.