The result of the planning process is key to achieving superior performance. As shown in this chapter, planning is far from trivial and involves various complex calculations. The more tables are touched by a query, the more complicated planning will become. The more tables there are, the more choices the planner will have. Logically, planning time will increase. At some point, planning will take so long that performing the classical exhaustive search is not feasible anymore. On top of that, the errors made during planning are so great anyway that finding the theoretically best plan does not necessarily lead to the best plan in terms of runtime.
Genetic query optimization (GEQO) can come to the rescue. ...
