alt Hacker NewsAny kind of uuid PK is quite expensive and usually not worth, because you're so frequently joining on PKs. A safe default is to use serial PKs, then have a secondary-indexed uuid4 if you wish to publicly-expose anything. Why uuid7, is the btree performance better with it than with uuid4?
In practice you’ll never notice the difference between joining on a bigint vs uuid for most OLTP purposes and you’ll be able to generate the uuids in your backend instead of in the db which a) can be very helpful if you’re pre-generating linked records and inserting them pipelined rather than sequentially, saving a lot of round trip traffic, b) reduces concurrency bottlenecks on the db server.
More usefully, a uuidv7 can take the place of both the id and the created_at field (if precision is sufficient), and can (depending on your security comfort) also take the place of the uuidv4 public id field.
With uuidv7 the data is naturally sorted so you don’t run into the issues with btree worst case scenarios that you would with a uuidv4 id, and you can even take it a step further and use BRIN instead of btree indexes for a massive boost (also applicable to serial ids, though).