Agree that scatter is expensive. We did actually have hopes for 4-way partition. Even ignoring the difficulties with doing that in-place, SIMD partition still s

Agree that scatter is expensive. We did actually have hopes for 4-way partition. Even ignoring the difficulties with doing that in-place, SIMD partition still seems to require one compressstore per partition. A quick prototype turned out to be half as fast as 2-way partition, which negates the gains from doing half as many passes (this depends on the ratio of compute to bandwidth, though).