Function mz_sql::plan::lowering::attempt_outer_join

fn attempt_outer_join(
    left: MirRelationExpr,
    right: MirRelationExpr,
    on: MirScalarExpr,
    kind: JoinKind,
    oa: usize,
    id_gen: &mut IdGen
) -> Result<Option<MirRelationExpr>, PlanError>

Attempts an efficient outer join, if on has equijoin structure.