alt Hacker NewsReally? Doesn’t v4 locally make the inserts into the B-Tree pretty messy? I was taught to use v7 because it allows writes to be a lot faster due to memory efficient paging by the kernel (something you lose with v4 because the page of a subsequent write is entirely random).
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In distributed databases I've worked with, there's usually something like a B-tree per key range, but there can be thousands of key ranges distributed over all the nodes in the cluster in parallel, each handling modifications in a LSM. The goal there is to distribute the storage and processing over all nodes equally, and that's why predictable/clustered IDs fail to do so well. That's different to the Postgres/MySQL scenario where you have one large B-tree per index.
v7 exposes creation date, and maybe you don't want that. So, depends on use-case
https://www.thenile.dev/blog/uuidv7#why-uuidv7 has some details: " UUID versions that are not time ordered, such as UUIDv4 (described in Section 5.4), have poor database-index locality. This means that new values created in succession are not close to each other in the index; thus, they require inserts to be performed at random locations. The resulting negative performance effects on the common structures used for this (B-tree and its variants) can be dramatic. ".
Also mentioned on HN https://news.ycombinator.com/item?id=45323008