谷歌如何如此快速地提供结果? [英] How does Google serve results so fast?

问题描述

当我一次又一次地在 Google 上搜索某个主题时，Google 返回结果并打印出一些统计信息，例如

Time and again when I search for a topic on Google, Google returns me the results and also prints out some stats like

j2me 的结果 1 - 10，共 8,850,000.(0.24 秒)"

"Results 1 - 10 of about 8,850,000 for j2me. (0.24 seconds)"

我注意到 Google 提供结果所需的秒数在几分之一秒范围内.

I notice that the seconds taken by Google to serve the results are in fraction of a second range.

谷歌如何提供如此快的页面，它最终使用了什么样的数据库优化技巧?

How does Google serve pages so fast, what kind of database optimization tricks has it used at its end?

推荐答案

我认为前端性能的主要原因是:

I think the main reason for the frontend performance are:

• 每个请求都被并行分发到一系列机器(我在某处读到每个查询大约有 12 台机器)，可能有一台机器收集这些机器的响应
• 所有索引数据都保存在 RAM 中.对于索引数据，我的意思是术语词汇表和帖子列表索引，在谷歌的情况下可能有更多的索引，例如用于拼写更正.即使在某处使用单个磁盘 I/O，磁盘寻道的延迟也会阻止这种性能.

• Each request is distributed to a series of machines in parallel (I have read somewhere that each query hits around 12 machines), probably a single machines gathers the responses from these machines
• All index data are held in RAM. With index data, I mean the term vocabulary and the postings list index and in the case of Google probably a lot more indexes e.g. for spelling corrections. Even with a single disk I/O somewhere the latency of the disk seek prevents such a performance.

Google 的 Map/Reduce、GFS 是很好的后台处理工具，但它们与前端性能无关.

Googles Map/Reduce, GFS are great tools for background processing, but they have nothing to do with the frontend performance.

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