Not a big fan of AresDB because of the glaring IO issues. That being said, pushing 'lack of join operator was never a problem' is textbook Sapir–Whorf. 'We've trained our captive users to never ask a question that requires a join, or use convoluted workarounds if they absolutely must do so, and we are proud of it' just leaves a bad taste. I wouldn't be surprised if Pinot were to add join support in the near future...