busybee fluffy rambles

Context: That is when the UNIX epoch rolls over from 9999999999 to 10000000000.

Normally base-10 numbers aren’t considered a problem when it comes to computers, but there are certainly systems out there that are assuming that UNIX epoch times converted to a string sort lexically¹. And on those systems, November 20, 2286 at 17:46:40 (GMT) will (lexically) sort lower than November 20, 2286 at 17:46:39.

And this is absolutely going to be a really subtle issue; at least in the current day and age, it’s pretty common for strings and integers to be used interchangeably and there only being a problem when mathematical operations are involved. Some languages even go so far as to implicitly convert when comparing them² So I can imagine plenty of circumstances where something is using the UNIX epoch time for something (say, a filename), then using a lexical sort or comparison to perform various find or delete operations. (For example, using the newest version of a file, or deleting files older than a certain reference time, or the like.)

Anyway, for this reason (among others) it’s best to use the ISO-8601 timestamp format for any long-term comparison methods, as it doesn’t run into any potential sorting problems³ until January 1, 10000. And if humans are even around that long, good luck to them!