The second part shows the estimated costs of the query 第二部分展示了该查询的估算成本。
The estimated costs are cost units that the optimizer uses to compare query plans 估算成本是优化器用来比较查询计划的成本单元。
Another factor that must be considered when enterprises decide on prices is cost 企业制定价格必须考虑成本因素,必须正确地估算成本。
A query with higher estimated costs generally takes longer to run than one with lower estimated costs 与具有较低估算成本的运行相比,具有较高估算成本的查询的运行时间通常更长一些。
The optimizer chose this query plan because the estimated cost for its execution was the lowest among all the evaluated plans 优化器将选择该查询计划,因为其执行的估算成本是所有被估计划中最低的。
If the transaction isolation mode is repeatable read , then the optimizer would base its choice purely on the estimated costs 如果事务隔离模式是可重复读( repeatable read ) ,那么优化器会将其选择完全基于估算成本。
If value is set to 2 , the optimizer would uses estimated costs to determine an execution plan regardless of the transaction isolation mode 如果将其值设置为2 ,优化器就会使用估算成本来确定执行计划,而不管事务隔离模式如何。
If the value is set to 0 , then the optimizer chooses index scans over table scans if appropriate indexes exist , without even considering the estimated costs 如果将其值设置为0 ,那么当存在合适的索引时,优化器就选择索引扫描而非表扫描,甚至不考虑估算成本。
There is a big push to use online decision - support tools to track , manage and justity costs . don ' t get blind - sided by new requirements for situation analyses 有一个巨大的推动器,利用在线决策支持工具来跟踪,管理和估算成本。不要盲目片面的,依据新的需求进行情况分析。
Given that the additional anti - warming steps that might be taken aren ' t yet known ? and so their net costs are impossible to state ? it is premature to dismiss them as “ phenomenally more expensive 事实上对抗全球暖化的其他方案目前还没出现,根本无法估算成本,现在就说绝对要花更多钱来驳斥这些方案,是草率、不负责任的。