Random UUID v4 makes a poor primary key: values land all over the index, so B-tree inserts scatter across pages and page splits go up. UUID v7 puts a millisecond timestamp in the leading bits (standardized in RFC 9562), so generation order equals sort order and you get locality back. I needed a...
Source: [Dev.to](https://dev.to/takahiro_hashito_a1f3f0dc/implementing-uuid-v7-by-hand-time-sortable-primary-keys-and-the-same-millisecond-trap-1l71)