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为什么搜索引擎能这么快? – 译学馆
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为什么搜索引擎能这么快?

How Are Search Engines So Fast?

你正在找一个文件 明明你刚刚才保存过的
You’re looking for a file,
你确定你刚刚保存好了
and you know that you’ve just saved it.
你也知道它保存在哪 可你就是没看见
You know where you hoped this file was saved,
可怎么也找不着了
but you just don’t see it.
这时你会搜索你的电脑 然而结果很令人沮丧
So you try searching your computer, and end up really frustrated.
这个文档十分钟后就要使用了 可你的电脑居然用这么宝贵的时间来搜索
This paper is due in ten minutes,
搜索的进度却相当缓慢
and your computer is taking its sweet time searching.
你也知道文件名没错 因为你刚刚才保存过
And you know you have the right filename
因为你刚刚才保存过
because you just saved it.
所以你问谷歌哪里是Word保存临时文件的地方
So you ask your friend Google
保存临时word文档的地方在哪里
where Word saves temporary files,
看看电脑到底出了什么故障
just in case your computer did something weird.
在目光所及之处 谷歌给了你一长列整齐而且有用的搜索结果
And in a blink of an eye,
谷歌就整理出了一列排好序的相关结果
Google gives you an ordered list of relevant results.
谷歌服务器浏览了上亿个网页
Google’s computers looked through trillions of Web pages,
将跟你这个问题有关的结果排出来 再列整齐放在你眼前
ranked their relevance to your specific problem,
并排好序列在你眼前
and listed them in order for you.
同时 你的电脑还在不停运转 比
Meanwhile, your computer keeps spinning away,
花比谷歌长几千倍的时间
taking thousands of times longer to search
搜索着相当于谷歌百万分之一大小的数据库
a database a million times smaller than Google’s.
所以谷歌是怎么做到的呢?
So how does Google do it?
你可能会认为这只是因为谷歌的计算机比你快而已
You might assume that Google’s computers
谷歌的计算机比你快而已
are just faster than yours,
或许有这个原因
and that’s probably true.
但是计算机的能力并不是谷歌这么神速的主要原因
But computing power isn’t the main reason for Google’s impressive speed.
这其实要归功于它们著名的算法
Instead, it comes down to their famous algorithm.
一个算法只是你要实现任何东西的一个程序步骤
An algorithm is just any kind of procedure
按着这程序步骤可以
that you follow in order to accomplish something.
谷歌或者其它搜索引擎利用这个算法让你所想要的结果
And with Google or any other search engine,
正是利用算法把你搜索的结果
the algorithm is what turns your search
显示到页面上
into pages of results.
这种算法运算速度之所以这么快是因为搜索引擎
The algorithm can work so fast
是因为搜索引擎并不是真的
because the search engine doesn’t actually
在点击搜索和呈现结果
look through those trillions of pages
这种中间一两秒的时间里
in that split-second between your search
筛选了几万亿的网页
and the results showing up on your screen.
那样会花费太多的时间 而且
That would take way too much time, and
现在已经不是那个慢悠悠拨号通话的时代了
this isn’t the dial-up era anymore.
我们需要马上得到结果
We want our results now.
所以搜索引擎并不会浏览全部你想要搜索的内容
Search engines don’t look through all those pages when you search
因为它们早就做过了
because they already did.
一个搜索引擎公司的计算机时时刻刻都在进行网络爬虫
A search engine’s computers are constantly crawling the Web.
从一个网站点击链接进入下一个网站
They follow links from site to site,
并建立巨大的列表库 记录各网站的词条
creating gigantic lists of which pages have which words,
这些词语出现的每一页还有
how many times those words appear on each page,
某一网页对于整个互联网的重要程度
how important those pages are
还有各种类似的其他内容
to the rest of the internet and all kinds of stuff like that.
总的来说 搜索引擎筛选信息和呈现结果
The exact way a search engine decides
的具体程序是保密的
which results to show you is generally a secret,
因为他们不想让网页欺骗系统
since they want to stop sites from gaming the system
从而成为高频搜索结果
so they’re higher in the search results.
但一切都取决于这些信息量巨大的列表
But it all depends on how these gigantic lists
如何被分类并整理到所谓的
are sorted and combined into what’s called
索引的地方
an index,
这跟你在书本的最后看到的索引差不多
which is a lot like the index you’d find in the back of a book.
当你搜索时
When you search,
搜索引擎的计算机只是浏览了索引
the search engine’s computers just check the index,
并把相关度最高的条目找到
find the entries that are most relevant,
把它们按最适合的顺序反馈给你
and then send them back to you in the right order.
听起来 这似乎
This might sound more complicated
比每次直接搜索网页更复杂
than searching the pages themselves each time,
但试想一下 从索引找到书中的某个内容
but think about how much easier it is to find something in the book’s index
不是比把书本每一页翻一遍来找要快得多吗
than it is to flip and skim through every page to find what you’re looking for.
利用索引更快
The index is faster
是因为制作索引的人已经为你
because whoever made it did all the work for you
把书本所有的标题很精心有序地排列起来了
by putting the book’s topics in a nice, orderly list.
他们的努力也值得了
And their hard work is worth it,
因为有了索引 你可以花比原本要少得多的时间
because the index lets you find whatever you want
找到任何你想要的信息
way faster than you could’ve otherwise.
同样 谷歌计算机也投入了大量的时间和精力来制作索引
Google’s computers also put a ton of time and effort into making the index,
他们的努力也得到了回报
but all that effort’s worth it.
谷歌索引显著提高了
The index dramatically speeds up each of the roughly forty thousand searches
每秒4万搜索任务的速度
that Google answers every single second.
那么 既然索引比直接搜索要更快
So why doesn’t your home computer or laptop make an index
为什么你的家用计算机和手提电脑不建立一个索引呢?
if it’s easier to search through than files themselves?
一些现代计算机已经这么做了
Well, some modern computers do,
这让他们搜索文件变得相当快
which lets them search for files pretty quickly.
如果你真的想要的话 还没有的电脑的也大多可以添加
And those that don’t can generally make an index if you ask nicely.
是真的 只要你改变一些设置
Or, really, if you change the right setting.
但也有些人
But some people tell their computers
不想让电脑添加索引
not to bother making an index,
因为创建和维持索引很花时间
because making and maintaining an index takes time
也很耗电 会让电脑运行变慢
and computer power that can slow a computer down.
没有索引辅助搜索 你的电脑很可能要
If you search without an index, your computer pretty much has to
浏览每一个文件来寻找你需要的信息
go through each of those files to see if it has what you’re looking for,
这也是为什么有时候用电脑搜索会慢的让人抓狂
which is why searching a computer can be so painfully slow sometimes.
这也是为什么你必须等着电脑
And that’s why you’re watching your ten minutes
筛选一个个音乐文件寻找你的期末论文
tick away as your computer asks
等着时间一直流逝
each and every song you own if it’s your term paper.
感谢收看本期SciShow
Thanks for watching this episode of SciShow,
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which was brought to you by our patrons on Patreon.
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If you want to help support this show, go to patreon.com/scishow,
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视频概述

通过建立索引,谷歌可以轻易获取相关词条,词条出现频率及网页重要程度

听录译者

收集自网络

翻译译者

陈榆木

审核员

赖皮

视频来源

https://www.youtube.com/watch?v=gIPIqOiSknY

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