I honestly don't remember for sure, but I believe it was one row per comment with a list of everyone who voted on it. So you could quickly get the answer to "d

I honestly don't remember for sure, but I believe it was one row per comment with a list of everyone who voted on it. So you could quickly get the answer to "did user X vote on comment Y?" And of course the answer from a bloom filter was either "no" or "probably yes?", which was good enough to then do an actual lookup of that person's vote on that comment.