Year 2038 problem
Unsigned integers will get you going till the year 2106, that could be an easy hotfix if you don't have to store datetimes before 1970.<p>Using 64-bit integers is overkill, they will work till the year 584bln[1] and it's twice as much data for every timestamp. Adding one byte (5-byte integers) is uncommon, but that supports the year 36000 already, so it would be more than enough.<p>[1] In full, till the year 584 942 419 325.