I don’t know how to count that low
Does it seem a little strange that a startup would not hire someone who had solved a harder problem (big concurrent sharded DB system) for not knowing exactly how to solve an easier problem (keep the database in memory)?OP seems to imply that is some kind of arrogance to believe that. Seems like, if you could figure out how to crack the first kind of problem, you could probably figure out how to crack the second. Maybe it's dismissive to say this, but it seems like this was a problem with the hiring org, not the author.