1·At each operator in the access plan, the optimizer estimates the cardinality output from the operator.
对于访问计划的每个操作符，优化器将估计该操作符的基数输出。
2·The optimizer calculates and compares the costs of each join method and selects the best one to use when evaluating query execution plans.
当评估查询执行计划时，优化器计算并比较每种连接方法的成本，然后选择要使用的最佳方法。
3·Tuning such an environment by only analyzing the optimizer plans is not feasible due to the quantity of produced plans.
由于所产生的计划数量太多，仅通过分析优化器计划来调优该环境是不可行的。
4·An entry is added to the system catalog to indicate to the query optimizer that such a remote index exists.
一个条目被添加到系统编目中，以向查询优化器表明存在那样的一个远程索引。
5·With this feature, the query optimizer can immediately consider the index when determining an access plan.
有了这个特性，查询优化器可以在决定访问计划时立即考虑索引。