Google’s index seems to be the freshest, MSN keeps its database up to date within 20 days, and Yahoo is chaotic.

A German university finds that while Google does the most daily page updates, MSN seems to be able to completely update pages within a twenty-day time frame. The study by Heinrich-Heine-University in Dsseldorf sought to find just how fresh a search engine index could be.

What the study does find is it looks like a miracle that search engines can manage to keep pace:

Furthermore the study can prove that a large amount of Web pages is changing on a regular basis. Estimating the results of the study for the whole Web, the authors find that there are about 320 million new pages every week. About 20 percent of the Web pages of today will disappear within a year. About 50 percent of all contents will be changed within the same period. The link structure will change even faster: About 80 percent of all links will have changed or be new within a year.
One test conducted by the university of a current event in Reuters found Google and Yahoo indexed the news story within an hour, as did AltaVista. Other search engines needed three hours to show this addition.

Groups containing German sites of national news portals, regional news, science, and certain special interests formed the control for the study. Only the German versions of Google, Yahoo, and MSN maintain their individual indices, which limited the study to considering only those search engines.

Researchers studied the period from February 15th to March 28th, 2005, and performed their tests daily. One finding in some preliminary work showed that Yahoo would have one-day old cached pages, and the next day have versions 9 or 10 days old. “We concluded that at least Yahoo could not guarantee constant updates of its index,” the study said.

David Utter is a staff writer for Murdok covering technology and business. Email him here.