A Combine whose where: compares ranges (a.t >= b.lo and a.t < b.hi, with or without an equality) runs on the block-band IEJoin path. Both sides are sorted and cut into blocks tagged with their key ranges; block pairs that cannot match are skipped; each surviving pair runs the IEJoin kernel, or a bounded nested loop when its matches would not fit; and the matches go through match: and on_miss: into one sorted output. This page runs that algorithm on small inputs, step by step, and checks every result against a brute-force join.
Solid green: kept, kernel ran · solid yellow: kept, too many matches for the pair budget, so the bounded nested loop ran · dashed: pruned by the min/max test · striped: different equality hash, never paired.