Google's Matt Cutts has released a number of
videos in which he talks about the way Google works. One of the videos addresses previous and future
updates of the Google index.
Google updates parts of its index daily A large fraction of Google's index is updated every day as Google crawls the web. That means that there is always an update going on.
In addition, Google has algorithms and data pushes that are going out on a less frequent basis. The latest were on 27 June, 28 July and 17 August. Unfortunately, Matt Cutts doesn't reveal any information about the details of these updates.
Google's BigDaddy update BigDaddy was a software infrastructure upgrade that finished in February. The BigDaddy update introduced a new way how they crawl the web.
Supplemental results This summer, Google also updated their supplemental results index structure. It was a complete rewrite and the indexing infrastructure for the supplemental results is different from then main indexing structure.
Another update is on the way Matt Cutts mentions in the video that another software infrastructure update is on the way. The new update should increase the quality of the search results:
"If we find out that we can improve quality by changing our algorithms or data or infrastructure, or anything else, we’re going to make that change.
The best SEO's in my experience are the ones that can adapt, and that say 'OK, this is the way the algorithms look right now to me, if I want to make a good site that will do well in search engines, this is the direction I want to head in next.'"
Matt Cutts talks about the different updates on Google but he doesn't say what this means to your web site. He doesn't reveal how Google's algorithms analyze your web pages.
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