aa8d7cd2_Cost_Based_Oracle_Fundamentals__Comments
[Chapter] Chapter 1 [Last addendum] 27th Feb 2006 [Title] What do you mean by cost? [Comments] 
You have to be very careful when talking about optimization and query performance; it’s too easy to mean two different things when you talk about the cost – the actual resource consumption, or the estimate of resource consumption. So this chapter is a little warning about the need for careful language.
Cost Based Oracle Fundamentals
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