That blogpost is a godsend, it provides a great explanation and intuition, and resolved a few questions that I was left with after reading a lot of WCO join pap

That blogpost is a godsend, it provides a great explanation and intuition, and resolved a few questions that I was left with after reading a lot of WCO join papers. Good nitpick, I think you can construct larger rings where the difference becomes larger than one, but I might be wrong. The dynamic variable ordering trick makes a huge difference in practice, especially when skew is in play. (https://arxiv.org/pdf/1310.3314.pdf https://arxiv.org/pdf/1310.3314.pdf) In general you're right, WCO joins are a relatively young field of study and sometimes struggle with large constant factors, but they are maturing quickly and in a limited (triple) setting like the one OP "wished for", a lot more feasible than for the general case. Thanks for the interesting discussions, looking forward to reading the references you provided in depth! Edit: I just remembered this paper, which might be of interest to you. They seem to recover WCO bounds in a pairwise setting, by choosing very smart intermediary join representations: http://www.cs.ox.ac.uk/dan.olteanu/papers/co-tr16.pdf http://www.cs.ox.ac.uk/dan.olteanu/papers/co-tr16.pdf