> Additionally using the less cryptographically secure uuid v1 can be a performance optimization since it has implicit time based sorting.
Except the way the fields are laid out basically defeats the point: UUIDv1 lays a 60 bits timestamp starting from the lower 32 bits, so it only sorts within a 7 minutes (2*32 * 100ns) bucket.
Hence the proposal for UUIDv6, which lays the exact same timestamp in reverse order (starting from the "top" 32b), making it naturally sortable.
Do check that they're not using a "cheating" implementation, I think some DBs have "sequential UUIDs" which are either UUIDv1 the right way up (aka uuidv6) internally, or an other scheme which yields a sequence (e.g. mssql's NEWSEQUENTIALID).
Alternatively, it's possible that they created pseudo-UUIDv1 by hand putting data in UUIDv6.
Except the way the fields are laid out basically defeats the point: UUIDv1 lays a 60 bits timestamp starting from the lower 32 bits, so it only sorts within a 7 minutes (2*32 * 100ns) bucket.
Hence the proposal for UUIDv6, which lays the exact same timestamp in reverse order (starting from the "top" 32b), making it naturally sortable.