Thursday, September 18, 2008

The Google Dance

The Google Dance

Approximately once a month, Google update their index by recalculating the Pageranks

of each of the web pages that they have crawled. The period during the update is known

as the Google dance.

Because of the nature of PageRank, the calculations need to be performed about 40 times

and, because the index is so large, the calculations take several days to complete. During

this period, the search results fluctuate; sometimes minute-by minute. It is because of

these fluctuations that the term, Google Dance, was coined. The dance usually takes

place sometime during the last third of each month.

Google has two other servers that can be used for searching. The search results on them

also change during the monthly update and they are part of the Google dance.

For the rest of the month, fluctuations sometimes occur in the search results, but they

should not be confused with the actual dance. They are due to Google's fresh crawl and to

what is known "Everflux".

Google has two other searchable servers apart from They are and Most of the time, the results on all 3 servers

are the same, but during the dance, they are different.

For most of the dance, the rankings that can be seen on www2 and www3 are the new

rankings that will transfer to www when the dance is over. Even though the calculations

are done about 40 times, the final rankings can be seen from very early on. This is

because, during the first few iterations, the calculated figures merge to being close to

their final figures.

You can see this with the Pagerank Calculator by checking the Data box and performing

some calculations. After the first few iterations the search results on www2 and www3

may still change, but only slightly.

During the dance, the results from www2 and www3 will sometimes show on the www

server, but only briefly. Also, new results on www2 and www3 can disappear for short

periods. At the end of the dance, the results on www will match those on www2 and


This Google Dance Tool allows you to check your rankings on www, www2 and www3

and on all 9 datacenters simultaneously.