presto-main/src/main/java/io/prestosql/sql/planner/QueryPlanner.java/QueryPlanner/offset
class QueryPlanner:    private PlanBuilder offset(PlanBuilder subPlan, Optional<Offset> offset)
    {
        if (!offset.isPresent()) {
            return subPlan;
        }

        return subPlan.withNewRoot(
                new OffsetNode(
                        idAllocator.getNextId(),
                        subPlan.getRoot(),
                        analysis.getOffset(offset.get())));
    }