When should I use uuid.uuid1() vs. uuid.uuid4() in python?

Question

I understand the differences between the two from the docs.

uuid1():
Generate a UUID from a host ID, sequence number, and the current time

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Answer 1

Perhaps something that's not been mentioned is that of locality.

A MAC address or time-based ordering (UUID1) can afford increased database performance, since it's less work to sort numbers closer-together than those distributed randomly (UUID4) (see here).

A second related issue, is that using UUID1 can be useful in debugging, even if origin data is lost or not explicitly stored (this is obviously in conflict with the privacy issue mentioned by the OP).