hello_olduncle

摘要： Note 1:What is a rounded cardinality?rounded card是执行计划时的预测数值original card是对象实际的原始的数值Note 2: auto trace和explain plan有哪些区别：a) explain plan does not bind variable peek, a real query would.b) explain plan sees all binds as varchar2's - in real life they are numbers, dates, varchar2's and so on. 阅读全文