Similar to the old situation in the article, we are using sequential 64 bit primary keys, but we use an additional random 64 bit key for external usage (instead of 128 bit).

The external key is base64 encoded for use in URLs which results in an 11 byte string.

This hides any information about the size of the data, the creation date of customer accounts (which would be sort of visible with UUIDv7) and prevents anyone from attempting to enumerate data by changing the integer in URLs.

I thought about using UUIDs as external keys but the only compelling use case seems to be the ability to generate keys from many decoupled sources that have to be merged later.

64 bit should be enough for most things https://youtu.be/gocwRvLhDf8?si=QBheJCG21bAAV0Z7