there's more index types than only hashes (which do indeed only support equality) e.g. btrees allow greater than/less than comparisons postgres supports these

there's more index types than only hashes (which do indeed only support equality) e.g. btrees allow greater than/less than comparisons postgres supports these and many more: https://www.postgresql.org/docs/9.5/indexes-types.html https://www.postgresql.org/docs/9.5/indexes-types.html