title: how to dertermine a query is better than the other from oracle EXPLAIN PLAN
body: <p>I am optimizing an oracle query. I found the cost of my new query is lower than the original one. I think my new query may have better performance than the old one. But lots of people on web say "the COST column cannot be used to compare execution plans".  So my question is how do you know the performance of one query is better than the other if you don't check the cost from the explain plan? Any other ways? Thanks!</p>