[choeger]

The author is talking about databases, not programming languages.

I do see a different issue, though: The article indeed seems to make no distinction between an absent value and a default timestamp of 0. That limits your database to more or less "now". You cannot really store things about the past. Someone might take such a pattern and fixate it into some kind of library. If then someone else tries to store data from 1970, things can get ... interesting.

[kedean]

That does assume your database only allows unix-style timestamps. MariaDB, for example, has "datetime", supporting dates between the year 1000 and 9999, distinct from null/zero.

Unfortunately, datetime takes 8 bytes vs the 4 for a timestamp.

[ghego1]

That is a very neat and smart improvement!