怎样理解执行计划?
待完善… The output may look like, Operation | Options | Object Name | Cost | Cardinality | Bytes Operation, Options: 数据库在这一步采取的操作及其使用的参数. 请参考 所有操作的集合 Object Name: Name of the table or index. Cost: a function of the CPU_COST and IO_COST. 它是无量纲的,仅用于各步操作的代价比较 Cardinality: the number of rows accessed by the operation Bytes: the number of bytes …