G select * from (values(1, 2), (3, 4)) as a(b, c); (before rewrites) cluster0 Box0:Select cluster2 Box2:Select cluster1 Box1:Values boxhead0 Distinct: Preserve 0: Q1.c0 as B 1: Q1.c1 as C Q1 Q1(F) as A boxhead2 Distinct: Preserve 0: Q0.c0 as B 1: Q0.c1 as C Q1->boxhead2 Q0 Q0(F) boxhead1 Distinct: Preserve 0: c0 as COLUMN1 1: c1 as COLUMN2 1, 2 3, 4 Q0->boxhead1