ULID is not sorted correctly on MS SQL SERVER. ULID is supposed to be sorted from left to right (left side is date) If you create a table with uniqueidentifier and DateTime, and then insert data into it in chronological order (ULID and date created at the same time) You will see that the dates are in random order. Also, my tests with the benchmark showed that the insertion time has a large spread from 2 to 22 seconds for inserting 100_000 rows. If you convert your ULID to string => nvarchar(26) then it will be sorted correctly. Or use long as snowflake id.