Interesting so you don't find it odd that an article about the storage engine of a SQL database system explains the solution to problem without once mentioning that it is the way most other sql database engines solve it? It is mentioned several times sql table are typically sparse, but not that this is how its typically solved, only this is how you solved it...

>The fix is simple: we stop storing Option<T> and instead we store a bitmap that records which fields are None.

Right here would have been the opportunity to let those not familiar with database internals know. Something like "This technique has been widely used in many RDBMS systems over the years, you can see the PG version of this in their documentation for page layout".

Instead you go into detail on what a null bitmap is and how to implement it, calling it a "trick". Which is strange if you think your target audience is assumed to already know this common technique.

I mean not one mention of the origin of the trick or even calling it a common solution to this problem...