One of the great advantages of using a query optimizer is the benefit of seeing your SQL transformed into a more efficient and faster one!
The Oracle Cost-Based Optimizer is able to change the SQL in multiple of ways, often many times just for a single SQL.
This is probably the main reason why analyzing the CBO trace (trace event 10053) is so painful and scary to many,
because who likes to read a 1 million lines long trace file?
This session will focus on the mechanics behind the query transformation framework and will illustrate an analytical
way to attack any CBO trace file decomposing it into smaller pieces, easy to analyze.