要减少执行时间，除非规则是柱状的，否则，在可能的情况下采用虚拟表，并避免使用抽样。
To reduce execution time, unless the rules are columnar, you should use virtual tables where possible, and avoid using sampling.
在这种情况下，执行时间从348.5秒减少到204.5秒，性能提高了41%。
Elapsed time in this particular case decreased from 348.5 seconds to 204.5 seconds, an improvement of 41%.
然而，远程执行时间上的重叠足以带来显著的性能提升：在没有异步的情况下，查询要运行432秒，而在有异步的情况下查询只需运行327秒，性能提高了24%。
However, the overlap in remote execution time is enough to bring about significant improvement: the query runs in 432 seconds without asynchrony and 327 seconds with asynchrony, an improvement of 24%.
避免准备阶段在下面两种情况下最有用：一是sql语句被多次执行；二是准备阶段需要的时间占语句总执行时间的很大一部分。
Avoiding the prepare phase especially pays off if an SQL statement is executed many times and if the prepare phase makes up a significant portion of the statement's overall execution time.
最后给出测试这两种程序的实验条件和任务，并对这两种程序在不同情况下的执行时间进行分析。
In the end, puts forward the condition and task of the experiment which purpose is to test these two programs and analyzes the executing time under diverse circumstances.
它会使你的脚本执行时间——通过使用更多的CPU周期，为了得到空闲内存，在大多数情况下，不会需要。
It will actually make your script execute longer - by using more CPU cycles - for the sake of getting free memory that would, in most cases, would never be needed.
描述了在串行迭代的情况下开发过程执行时间的计算方法。
The way of calculating work time under the circumstance of sequence iteration is described.
描述了在串行迭代的情况下开发过程执行时间的计算方法。
The way of calculating work time under the circumstance of sequence iteration is described.
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