墨菲定律与 DBA
今天参加培训的时候胡思乱想,忽然间想起来墨菲定律(Murphy's Law)这个有趣的话题. 西方文化中，有很多所谓的"定律", 墨菲定律应该算是一则比较著名的"定律"了.什么是墨菲定律? 最简单的表达形式是"有可能出错的事情，就会出错(Anything that can go wrong will go wrong)"。
爱德华·墨菲、约翰·保罗·斯特拉普和乔治·尼克斯凭这条定律居然还得到了搞笑诺贝尔奖(IgNobel)奖。而墨菲定律的一些衍生版本也的确有趣.比如"东西久久都派不上用场，就可以丢掉；东西一丢掉，往往就必须要用它",再比如"你出去买爆米花的时候，银幕上偏偏就出现了精采镜头".
抛开 Murphy's Law 衍生出来如此多的版本不谈，说一下墨菲定律和 DBA 之间的关系。Anything that can go wrong will go wrong, 这句话对 DBA 来说，应该是引起注意的, 甚至作为金科玉律也不为过,一般来说，没有哪一个人管理的数据库是完美无缺的，但是如果你发现了数据库的缺限置之不理，存在侥幸心理，那么最后往往会发生你最担心的问题。我就曾经亲生经历过几起类似的事件，事后总结的时候想 "如果我...如何做" 就好了. 但是已经发生的事情就不允许假设了.
引用一下这个定律的来龙去脉:
Murphy's Law ("If anything can go wrong, it will") was born here (Edwards Air Force Base) – in 1949 at North Base.It was named after Capt. Edward A. Murphy, an engineer working on Air Force Project MX981, (a project) designed to see how much sudden deceleration a person can stand in a crash.
One day, after finding that a transducer was wired wrong, he cursed the technician responsible and said, "If there is any way to do it wrong, he'll find it."
The contractor's project manager kept a list of "laws" and added this one, which he called Murphy's Law.
Actually, what he did was take an old law that had been around for years in a more basic form (see first paragraph above) and give it a name.
Shortly afterwards, the Air Force doctor (Dr. John Paul Stapp) who rode a sled on the deceleration track to a stop, pulling 40 Gs, gave a press conference. He said that their good safety record on the project was due to a firm belief in Murphy's Law and in the necessity to try and circumvent it.
Aerospace manufacturers picked it up and used it widely in their ads during the next few months, and soon it was being quoted in many news and magazine articles. Murphy's Law was born.
The Northrop project manager, George E. Nichols, had a few laws of his own. Nichols' Fourth Law says, "Avoid any action with an unacceptable outcome."
The doctor, well-known Col. John P. Stapp, had a paradox: Stapp's Ironical Paradox, which says, "The universal aptitude for ineptitude makes any human accomplishment an incredible miracle."
Nichols is still around. At NASA's Jet Propulsion Lab in Pasadena, he's the quality control manager for the Viking project to send an unmanned spacecraft to Mars.
由上面的介绍可以看出,如果积极的看墨菲定律, 对提高系统的品质是有积极的作用的. 所以 DBA 、SA 朋友们,时刻把这个准则放在心里, 防患于未然.