In my ERP Oracle database I see most of the sql with USE_NL, is that bad?? - Don't use plan-restricting hints, except in test situations where you're trying to cause bad performance. For example, don't use hints like RULE, [ USE_NL, INDEX, USE_HASH, FULL, AND_EQUAL, etc. in production. If you really want plan stability, stored outlines can give you that. But the adaptive intelligence of a well-informed and properly functioning CBO is a smarter long-term decision except in rare cases.