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Google Dance
In the past, Google typically performed monthly updates called the “Google Dance” among the experts. At the beginning of the month, a deep crawl of the web took place, then after a couple of weeks the PageRank for the retrieved pages was calculated, and at the end of the month the index database was finally updated. Nowadays, Google has switched to an incremental daily update model (sometimes referred to as everflux) so the concept of Google dance is quickly becoming historical.
The “Dance” took place from time to time but only when they need to make major changes to their algorithm. For example, their dance in November 2003 (known as Google Florida Update) was actually their first after about six months. In January 2004, Google started another dance (Austin Update) where pages that had disappeared during the “Florida” showed up again, and many pages that hadn’t disappeared the first time were gone.
In February 2004 Google updated once more and things settled down. Most people who had lost pages saw them return and although the results were rather different than those shown before Florida, at least pages didn’t seem to disappear for no reason.
Google claims to have 1 trillion (as in 1,000,000,000,000) unique URLs in its index. The engine constantly adds new pages to the index database – usually it takes around two days to list a new page after the Googlebot (Google’s spider) has crawled it. The Google team works industriously towards algorithm perfection to keep their leading position amongst search engines.
These days, Google maintains a database which is continuously updated. Matt Cutts (head of Google’s Webspam team) reported in his personal blog that :
«Google switched to an index that was incrementally updated every day (or faster). Instead of a monolithic monthly event, the Google would refresh some of its index pretty much every day, which generated much smaller day-to-day changes that some people called everflux.»
Google has lots of so-called “regional” branches, such as “Google Australia“, “Google Canada,” etc. These branches are modifications of their index database stored on servers located in the corresponding regions. They are meant to further adjust search results to searcher needs: when you’re searching, Google detects your IP address (and thus approximate location) and feeds the results from the most appropriate index database.
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