Using STP algorithm, the leastcost paths between nodes are computed when computing the working tree, so the best backup path can be found as soon as the failure occurs.
在组播树建立之初，计算好组播节点之间的最小代价路径，以便于出现故障之后寻找最优备用链路；
2
Before SQL is executed, the DB2 optimizer estimates the cost of the candidate access paths and selects the path with the least estimated cost.
在执行SQL之前，DB 2优化器会评估候选访问路径的成本，然后选择成本最低的路径。
3
So the most optimal path planning is regard as the problem of searching for roads which have the leastcost in a road net.