The preprint “POLAR: Adaptive and Non-invasive Join Order Selection via Plans of Least Resistance” introduces an adaptive query processing technique that lowers the adoption barrier for existing database systems while decreasing the risk of performance cliffs from ill-performing query plans.The preprint “POLAR: Adaptive and Non-invasive Join Order Selection via Plans of Least Resistance” introduces an adaptive query processing technique that lowers the adoption barrier for existing database systems while decreasing the risk of performance cliffs from ill-performing query plans.[#item_full_content]