Google dance ends?
Google Dance - Has it ended?
The Index Update of the Google Search Engine
There have been indications that the google dance, as it was known, is being retired in favour of a continuous update by the google search engine. We can only wait to see what google has in mind for the future. (August 2003).
Google Dance
The name "Google Dance" is often used to describe the index update of the Google search engine. Google's index update occurs on average once per month. It can be identified by significant movement in search results and especially by Google's cache of all indexed pages reflecting the status of Google's last spidering. But the update does not proceed as a switch from one index to another at one point in time. In fact, it takes several days to complete the index update. During this period, the old and the new index alternate on www.google.com. At an early stage, the results from the new index occur sporadically. But later on, they appear more frequently.
Watch it happen at www.google-dance.com
The Google search engine pulls its results from more than 10,000 servers which are simple Linux PCs that are used by Google for reasons of cost. Naturally, an index update cannot be proceeded on all those servers at the same time. One server after the other has to be updated with the new index. Many webmasters think that, during the Google Dance, Google is in some way able to control if a server with the new index or a server with an old index responds to a search query. But, since Google's index is inverse, this would be very complicated. In fact, The reason for the Google Dance is Google's way of using the Domain Name System (DNS).
Not only Google's index is spread over more than 10,000 servers, but also these servers are, as of now, placed in eight different data centers. These data centers are mainly located in the US (i.e. Santa Clara, California and Herndon, Virginia), indeed, in June 2002 Google's first European data center in Zurich, Switzerland went online. Very likely, there are more data centers to come, which will perhaps be spread over the whole world. However, in January 2003 Google has put a data center on stream which is again located in the US. In order to direct traffic to all these data centers, Google could thoeretically record all queries centrally and then send them to the data centers. But this would obviously be inefficient. In fact, each data center has its own IP address (numerical address on the internet) and the way these IP addresses are accessed is managed by the Domain Name System. Basically, the DNS works like this: On the Internet, data transfers always take place in-between IP addresses. The information about which domain resolves to which IP address is provided by the name servers of the DNS. When a user enters a domain into his browser, a locally configured name server gets him the IP address for that domain by contacting the name server which is responsible for that domain. (The DNS is structured hierarchically. Illustrating the whole process would go beyond the scope of this paper.) The IP address is then cached by the name server, so that it is not necessary to contact the responsible name server each time a connection is built up to a domain.
Most webmasters are interested in ranking changes for their website during the Google Dance. But, besides that, many also want to know about their new PageRank values. Normally, the Google Toolbar fetches the PageRank values from the data center that is specified by its IP address in the actual DNS record for www.google.com. Hence, when the Google Dance begins, the Toolbar usually displays the old PageRank values. Google submits PageRank values in simple text files to the Toolbar. In former times, this happened via XML. The switch to text files occured in August 2002.
PageRank and Google are trademarks of Google Inc., Mountain View CA, USA.
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(c)2002-2003 eFactory Internet-Agentur KG - written by Markus Sobek
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