Best way to count uniques?

apenster

High!

In a tutorial the author wrote that you can count unique visitors in 3 ways:
- store ip address and then perform checks
- program something for server environment
- cookies

Author says cookies are the best. But I want to hear your opinion. What is the best way to count uniques for a large site? For example, how do sites like microsoft and cnet count their uniques?

Thanks in advance!

laserlight

Cookies can make it easy - if the cookie exists, then the visitor should not be re-counted (pretty much a constant time check). Unfortunately, there's no guarantee that the user will not delete the cookie, or even reject it to begin with.

Storing IP address means time spent searching the list of IP addresses for a match (takes linear time, or at least O(log n) if the list is sorted) - plus users may share the same IP address.

I'm not sure what the author of your article had in the mind with "program something for server environment".

apenster

laserlight wrote:
Cookies can make it easy - if the cookie exists, then the visitor should not be re-counted (pretty much a constant time check). Unfortunately, there's no guarantee that the user will not delete the cookie, or even reject it to begin with.

Storing IP address means time spent searching the list of IP addresses for a match (takes linear time, or at least O(log n) if the list is sorted) - plus users may share the same IP address.

I'm not sure what the author of your article had in the mind with "program something for server environment".

Thanks for quick reply.

Did the author mean server sessions?

And how do you do it laserlight?

So, if I understand correct IP based script is not feasible for say, 100 000 uniques per day? Cookie is. And I don't think that many peeps have cookies off.

I'm sill interested in this other method.

laserlight

Did the author mean server sessions?

I doubt it. The eventual persistence of the session should be maintained by a cookie.

And how do you do it laserlight?

I dont normally track unique users, but I would probably use a cookie.