If you didn’t see this post about better date-based searching by Ionut Alex Chitu, I highly recommend that you check it out. As Google has gotten fresher, our advanced search page started showing more useful options for restricting searches by date. The shortest time frame used to be something like three months; now you can look for things that are less than 24 hours old.
What GoogleOS noticed is that the advanced date search affects a url parameter called “as_qdr” and Chitu figured out some of the possible values:
The nice thing is that you can change the value of as_qdr to custom intervals. Here are all the possible values of the as_qdr parameter:
d[number] – past number of days (e.g.: d10)
w[number] – past number of weeks
y[number] – past number of years
For example, there’s been a lot of fast progress on iphone stuff recently. A query such as http://www.google.com/search?q=iphone+source+code&as_qdr=d1 would show all the new urls for the query [iphone source code] within the last day, because d1 stands for 1 day.
Suppose you wanted to see all the new urls that Google found on your site within the last 7 days. For the domain mattcutts.com, I’d use a query such as http://www.google.com/search?q=site:mattcutts.com&as_qdr=d7 to find those urls (remember, “d” stands for days and “7″ stands for, well, 7). Previously, you could check whether Google had indexed a new url by (say) searching for content from that url, so this isn’t completely new, but it still simplifies life for site owners.
I’m already using this parameter in my power searching all the time. If you need a way to remember the parameter name, I think of as_qdr as “advanced search — query date range,” although I haven’t checked if that’s what the letters actually stand for.