Oh. My. Goodness. Arguably one of the most important events for a weblogger is going to happen within days. The Google Dance! The time when Google updates its index and page rankings. Oliver just let me a comment which pointed to this FAQ about the Google Dance which I find incredibly fascinating. I knew that Google's page rank changes on a schedule of some sort only because every month or so I'd start seeing posts on weblogs about how their ranking has changed for the better or worse. A wave of posts cheering or lamenting their position in Google's world, and then it's quiet for a while. Well prepare yourself, it looks like it's coming again:
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. Google dances.
The start dates of previous Google Dances have been compiled by WebmasterWorld's administrator Brett Tabke. The previous Google Dance took place from 01/26/2003 to 01/29/2003. The next Google Dance was expected to take place by the end of February (it is a little behind schedule) and we will report about it. But mainly, the reasons for the Google Dance shall be presented here.
The begin of a Google Dance can always be watched at the test domains www2.google.com and www3.google.com. Those domains normally have stable DNS records which make the domains resolve to only one (often the same) IP address. Before the Google Dance begins, at least one of the test domains is assigned the IP address of the data center that receives the new index first.
Building up a completely new index once per month can cause quite some trouble. After all, Google has to spider some billion documents an then to process many TeraBytes of data. Therefore, testing the new index is inevitable. Of course, the folks at Google don't need the test domains themselves. Most certainly, they have many options to check a new index internally, but they do not have a lot of time to conduct the tests.
So, the reason for having www2 and www3 is rather to show the new index to webmasters which are interested in their upcoming rankings. Many of these webmasters discuss the new index at the Google forums out on the web. These discussions can be observed by Google employees. At that time, the general public cannot see the new index yet, because the DNS records for www.google.com normally do not point to the IP address of the data center that is updated first when the update begins.
As soon as Google's test community of forums members does not find any severe malfunctions caused by the new index, Google's DNS records are ready to make www.google.com resolve the the data center that is updated first. This is the time when the Google Dance begins. But if severe malfunctions become obvious during this test phase, there is still the possibility to cancel the update at the other data centers. The domain www.google.com would not resolve to the data center which has the flawed index and the general public could not take any notice about it. In this case, the index could be rebuilt or the web could be spidered again.
Amazing article. If you're doing any publishing on the web, you need to read it. Changes in Google could bring more traffic to your page overnight or cause other changes that you need to be aware of. Very cool.
Since Google hasn't updated its index since I started cacheing all my weblog pages as well as started getting the massive number of hits I've got in February, I hopefully should move up... "Russell" could be mine! We'll see. There's also less focus on my main home page, so that could affect things, and Google might adjust their algorithm for weblogs again, so that's something to take into account as well.
I feel like a zealot waiting for a celestial event! The Google Dance is Coming! All Praise Google. Google Knows All!