Unfortunately most "web-scale" apps I've worked on are basically immutable (aside from retention policies). You just keep appending forever because updates are

Unfortunately most "web-scale" apps I've worked on are basically immutable (aside from retention policies). You just keep appending forever because updates are too expensive. So more than likely your comment history will exist on Reddit's servers but they use a clever "GROUP BY" semantic on read to only return the most recent version.