I'm going to preface this criticism by saying that I think exercises like this are fun in an architectural/prototyping code-golf kinda way.
However, I think the author critically under-guesses the sizes of things (even just for storage) by a reasonably substantial amount. e.g.: Quote tweets do not go against the size limit of the tweet field at Twitter. Likely they are embedding a tweet reference in some manner or other in place of the text of the quoted tweet itself but regardless a tweet takes up more than 280 unicode characters.
Also, nowhere in the article are hashtags mentioned. For a system like this to work you need some indexing of hashtags so you aren't doing a full scan of the entire tweet text of every tweet anytime someone decides to search for #YOLO. The system as proposed is missing a highly critical feature of the platform it purports to emulate. I have no insider knowledge but I suspect that index is maybe the second largest thing on disk on the entire platform, apart from the tweets themselves.
However, I think the author critically under-guesses the sizes of things (even just for storage) by a reasonably substantial amount. e.g.: Quote tweets do not go against the size limit of the tweet field at Twitter. Likely they are embedding a tweet reference in some manner or other in place of the text of the quoted tweet itself but regardless a tweet takes up more than 280 unicode characters.
Also, nowhere in the article are hashtags mentioned. For a system like this to work you need some indexing of hashtags so you aren't doing a full scan of the entire tweet text of every tweet anytime someone decides to search for #YOLO. The system as proposed is missing a highly critical feature of the platform it purports to emulate. I have no insider knowledge but I suspect that index is maybe the second largest thing on disk on the entire platform, apart from the tweets themselves.