I looked into this, and (apparently) the cube extension has a very small hard-coded dimensionality limit that isn't sufficient for this purpose; you can recompi

I looked into this, and (apparently) the cube extension has a very small hard-coded dimensionality limit that isn't sufficient for this purpose; you can recompile it to support more dimensions, but the way it stores data requires the entire vector to still fit within a single database page (which these vectors will not).