PostgreSQL function to compare version 1 (time-based) UUIDs based on timestamps, and tests for it.
Example:
SELECT uuids_v1_compare(uuid('762ca430-eed5-11e5-8ca8-4bebdf3c407a'),
uuid('762cf250-eed5-11e5-8ca8-4bebdf3c407a'))
uuids_v1_compare
smallint
----------------
-1
A blog post about it.