One More Frown Please? (UPaxos Quorum Overlaps)

There was some discussion around UPaxos safety on a gist where Dave Turner was kind enough to clarify a confusion of mine. I had said that we needed an overlap between prepare quorums to avoid a split-brain. This was incorrect and I am greatful for Dave for correcting my misunderstanding. Yet there was something about not having that overlap that was bugging me… This morning I had an “Aha!” moment: if it exists then Trex will perform an optimisation. Yet in Trex this overlap is not enforced.

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