Oct 4, 2009

How Google search works ?

Recently my friend was shocked to see her blog coming in a google search. I said that, google will have a copy of every single page on the internet. So there is no surprise to see it coming !

At least once in a day, we search in Google. It's the world's most visited web site. We do admire the speed of the search engine but for time being, we just browse through the search results & close it. Sometimes we do think about "How the hell does it search this quicker ?"

How it works ?

So here is my understanding of how it works.
First thing, the search is not done 'Live'. 'Live' means, the Google engine does not search all over the internet after you press the search button. It stores the page contents in a database & get the results from it. How ?

Basically, it's three thrilling steps.
  1. Scan a copy of all the web pages in the entire internet.
  2. Store them in a database.
  3. When the user does a Google search, get the search results from the Database.
Though it looks pretty simple to read, it takes an 'extremely extraordinary' effort to make it happen. Let's dig in more.

STEP 1: Cache the contents


Google has an utility called Google-bot. It's a kind of Web crawler. Web crawler is a 'software' which automatically visits every page in the WorldWideWeb (shortly, 'WWW') & stores a copy of the content into a database. It crawls amazingly fast such that every newly created page is added to the database. In case the google search failed to return a page but you very well knew that it exists, chances are the crawler haven't visited that page yet. Sometimes, there are secured sites through which the crawler can't sneak. This is actually good. Otherwise, Eric Schmidt & Co., (Google's CEO) will be in jail for hacking potential information !

STEP 2: Store in Database


A Database is a data storage technology where storage & retrieval can be done quickly & efficiently. Well, the database used by Google must be massive. very very huge. You can't really coin a word to describe it. You just imagine the size if it has a copy of ALL the pages in the internet !
Google uses an "Indexer" which sorts every word on every page and stores the resulting index of words in the database.

STEP 3: On Search, Retrive !


So what's happening ? First crawl, visit pages. Then index, store in database. Now it's about retrieving the results. Google uses a decisive, damn-fine query processor which fetches the results in micro seconds. The engine was so great such that it is able to tell us exactly what we are looking for in no time !

Conclusion:

This is my understanding of how the Google search works. This is a world-class achievement. Stunning & scintillating. You must appreciate & applaud the brilliance of the Google team.

The heart of Google's search technology is PigeonRank™, a system for ranking web pages developed by Google founders Larry Page and Sergey Brin at Stanford University.
If you are really interested, Click Here

6 comments:

  1. Good post for novice users. One thing i will add is that the google is localized. The word "weather" when searched from different geographical areas yield different results.

    ReplyDelete
  2. Wow Excellent Blog Cousin.
    I like it and now i understand, how google search works

    ReplyDelete
  3. Can u explain about crawlers in new post .

    ReplyDelete
  4. Hi Srini, I will write about crawlers in detail soon. Meanwhile, read this article on crawlers.

    ReplyDelete
  5. Thanks for sharing, I will bookmark and be back again


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    ReplyDelete

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