How Does Google's "index" find the location of pages in the "page directory" to return?
-
This is my understanding of how Google's search works, and I am unsure about one thing in specific:
- Google continuously crawls websites and stores each page it finds (let's call it "page directory")
- Google's "page directory" is a cache so it isn't the "live" version of the page
- Google has separate storage called "the index" which contains all the keywords searched. These keywords in "the index" point to the pages in the "page directory" that contain the same keywords.
- When someone searches a keyword, that keyword is accessed in the "index" and returns all relevant pages in the "page directory"
- These returned pages are given ranks based on the algorithm
The one part I'm unsure of is how Google's "index" knows the location of relevant pages in the "page directory". The keyword entries in the "index" point to the "page directory" somehow. I'm thinking each page has a url in the "page directory", and the entries in the "index" contain these urls. Since Google's "page directory" is a cache, would the urls be the same as the live website (and would the keywords in the "index" point to these urls)?
For example if webpage is found at wwww.website.com/page1, would the "page directory" store this page under that url in Google's cache?
The reason I want to discuss this is to know the effects of changing a pages url by understanding how the search process works better.
-
Yeah that makes sense. I also have a lot of experience with databases and the back ends of websites so I know your language.
I'm wondering how Google correlates the url with the page entries then. Maybe each page entry would have a url field so Google knows the location of the live version to constantly update that entry in the "page directory" database?
-
That is a question that no one here can answer. We cant speak for how Google does things internally.
but.... as a web / database programmer for 14+ years let me tell you how its "generally" done
Usually when you have to link to separate sets of data together (ie. database or tables) there is usually a unique_id created to link them which usually is never changed. So when a new record is created that record will live with that ID for its life, also known as a (unique identifier which tends to be an auto-incremented number that is dynamically generated and can not be repeated).
Since records tend to be linked this way, any other fields that exist in the record (firstName, lastName, Url, blah blah) then can be changed without the original ID being disturbed.
So to answer your question from my experience I would assume Google links from a unique identifier of some sort and not the URL directly.
Hope I didn't lose you, its my favorite subject...but no one here speaks that language to much
-
That makes sense, thanks for getting back to me so fast!
Perhaps you can help answer my next question. I have a client who used to host his domain at "www.oldurl.com", and has migrated his website to "www.newurl.com". He wants to use his old domain "www.oldurl.com", so he setup forwarding/masking so that when someone tries to access "www.oldurl.com" they are forwarded to "www.newurl.com" but the url shown to the user is "www.oldurl.com".
My client want his old url "www.oldurl.com" to be ranked in Google, but from what I understand his new url will be ranked. I know masking is really bad for SEO, and I want to educate my client as to why on the technical side. I have read Google see's all the content as duplicate with masking. Do you know the details as to why?
-
Hey Cesar,
Thanks for the links! Really useful info there.
Unfortunately they I couldn't find the answer I was looking for so I'll be more specific in what I'm asking.
From what I understand Google uses two database systems. One contains keywords and the other contains cached pages. How does a keyword entry point to a page entry? Does it use a unique id number, or does it use the url that page is using in the "live" vesion on the web?
-
Just because you create a new page and delete the old one, Google won't know immediately about it. So if Google crawls the new page before it's had a chance to crawl the old one, then it will indeed consider the new page to be duplicate content. Then when it tries to crawl the old page, it will discover that it no longer exists. However, as long as links to the old page exist, it will continue to try to crawl that page. Eventually it may de-index the old page if it keeps returning an error.
Bottom line, if you are moving content to a new URL, be sure to include a 301 redirect on the old page so that Google (and other search engines) know that the piece of content has moved. You can also do this with canonical tags, but 301s are more effective.
-
Thanks for the response and links Takeshi. Maybe I can rephrase the question to be more clear. Let's say a piece of content (or page) is at the url "www.oldurl.com/page". During a migration this same piece of content now at the url "www.newurl.com/page". The "www.oldurl.com" doesn't exist anymore so there isn't duplicate content in the live web.
Would Google create a new entry in it's "page directory" (what is the industry standard name for this directory?) and give it the url "www.newurl.com/page"?
If it does create a new entry, would Google keep the old entry "www.oldurl.com/page" although the old url doesn't exist in the "live" web anymore?
-
Wow you just asked questions that would require about 10,000,000,000 answers
Lets start here
- Video from the man himself Mr. Matt Cutts - Matt Cutts (Works for Google)
- Great Web 2.0 Page create from Google themself - (Google Them self)
- Older but still relevant description about how "backlinks" affect PR - (Google Them self)
-
This a pretty confusing question, and the terminology you use is different from industry standard. Check out these links for a quick overview of how Google works:
- http://www.google.com/insidesearch/howsearchworks/thestory/
- http://www.googleguide.com/google_works.html
If you are just worried about changing a page's url, just be sure to put in a 301 redirect from the old page to the new page. That way, even if Google has an older version of the page indexed, it will automatically redirect the user to the new page as well as help Google discover the new location of the page.
Got a burning SEO question?
Subscribe to Moz Pro to gain full access to Q&A, answer questions, and ask your own.
Browse Questions
Explore more categories
-
Moz Tools
Chat with the community about the Moz tools.
-
SEO Tactics
Discuss the SEO process with fellow marketers
-
Community
Discuss industry events, jobs, and news!
-
Digital Marketing
Chat about tactics outside of SEO
-
Research & Trends
Dive into research and trends in the search industry.
-
Support
Connect on product support and feature requests.
Related Questions
-
Indexed pages
Just started a site audit and trying to determine the number of pages on a client site and whether there are more pages being indexed than actually exist. I've used four tools and got four very different answers... Google Search Console: 237 indexed pages Google search using site command: 468 results MOZ site crawl: 1013 unique URLs Screaming Frog: 183 page titles, 187 URIs (note this is a free licence, but should cut off at 500) Can anyone shed any light on why they differ so much? And where lies the truth?
Technical SEO | | muzzmoz1 -
How to Find all the Pages Index by Google?
I'm planning on moving my online store, http://www.filtrationmontreal.com/ to a new platform, http://www.corecommerce.com/ To reduce the SEO impact, I want to redirect 301 all the pages index by Google to the new page I will create in the new platform. I will keep the same domaine name, but all the URL will be customize on the new platform for better SEO. Also, is there a way or tool to create CSV file from those page index. Can Webmaster tool help? You can read my question about this subject here, http://www.seomoz.org/q/impacts-on-moving-online-store-to-new-platform Thank you, BigBlaze
Technical SEO | | BigBlaze2050 -
I am trying to correct error report of duplicate page content. However I am unable to find in over 100 blogs the page which contains similar content to the page SEOmoz reported as having similar content is my only option to just dlete the blog page?
I am trying to correct duplicate content. However SEOmoz only reports and shows the page of duplicate content. I have 5 years worth of blogs and cannot find the duplicate page. Is my only option to just delete the page to improve my rankings. Brooke
Technical SEO | | wianno1680 -
Video thumbnail pages with "sort" feature -- tons of duplicate content?
A client has 2 separate pages for video thumbnails. One page is "popular videos" with a sort function for over 700 pages of video thumbnails with 10 thumbnails and short desriptions per page. (/videos?sort_by=popularity). The second page is "latest videos" (/videos?sort_by=latest) with over 7,000 pages. Both pages have a sort function -- including latest, relevance, popularity, time uploaded, etc. Many of the same video thumbnails appear on both pages. Also, when you click a thumbnail you get a full video page and these pages appear to get indexed well. There seem to be duplicate content issues between the "popular" and "latest" pages, as well as within the sort results on each of those pages. (A unique URL is generated everytime you use the sort function i.e. /videos?sort_by=latest&uploaded=this_week). Before my head explodes, what is the best way to treat this? I was thinking a noindex,follow meta robot on every page of thumbnails since the individual video pages are well indexed, but that seems extreme. Thoughts?
Technical SEO | | 540SEO0 -
Different version of site for "users" who don't accept cookies considered cloaking?
Hi I've got a client with lots of content that is hidden behind a registration form - if you don't fill it out you can not proceed to the content. As a result it is not being indexed. No surprises there. They are only doing this because they feel it is the best way of capturing email addresses, rather than the fact that they need to "protect" the content. Currently users arriving on the site will be redirected to the form if they have not had a "this user is registered" cookie set previously. If the cookie is set then they aren't redirected and get to see the content. I am considering changing this logic to only redirecting users to the form if they accept cookies but haven't got the "this user is registered cookie". The idea being that search engines would then not be redirected and would index the full site, not the dead end form. From the clients perspective this would mean only very free non-registered visitors would "avoid" the form, yet search engines are arguably not being treated as a special case. So my question is: would this be considered cloaking/put the site at risk in any way? (They would prefer to not go down the First Click Free route as this will lower their email sign-ups.) Thank you!
Technical SEO | | TimBarlow0 -
Pages not Indexed after a successful Google Fetch
I am trying to understand why google isn't indexing key content on my site. www.BeyondTransition.com is indexed and new pages show up in a couple of hours. My key content is 6 pages of information for each of 3000 events (driven by mySQL on a wordpress platform). These pages are reached via a search page, but no direct navigation from the home page. When I link to an event page from an indexed page it doesn't show up in search results. When I use fetch on webmaster tools the fetch is successful but is then not indexed - or if it does appear in results it's directed to the internal search page e.g. http://www.beyondtransition.com/site/races/course/race110003/ has been fetched and submitted with links but when I search for BeyondTransition Ironman Cozumel I get these results.... So what have I done wrong and how do I go about fixing it? All thoughts and advice appreciated Thanks Denis
Technical SEO | | beyondtransition0 -
Does page speed affect what pages are in the index?
We have around 1.3m total pages, Google currently crawls on average 87k a day and our average page load is 1.7 seconds. Out of those 1.3m pages(1.2m being "spun up") google has only indexed around 368k and our SEO person is telling us that if we speed up the pages they will crawl the pages more and thus will index more of them. I personally don't believe this. At 87k pages a day Google has crawled our entire site in 2 weeks so they should have all of our pages in their DB by now and I think they are not index because they are poorly generated pages and it has nothing to do with the speed of the pages. Am I correct? Would speeding up the pages make Google crawl them faster and thus get more pages indexed?
Technical SEO | | upper2bits0 -
Removing a site from Google's index
We have a site we'd like to have pulled from Google's index. Back in late June, we disallowed robot access to the site through the robots.txt file and added a robots meta tag with "no index,no follow" commands. The expectation was that Google would eventually crawl the site and remove it from the index in response to those tags. The problem is that Google hasn't come back to crawl the site since late May. Is there a way to speed up this process and communicate to Google that we want the entire site out of the index, or do we just have to wait until it's eventually crawled again?
Technical SEO | | issuebasedmedia0