Unique ID's in ColdFusion 8?

Question

What tools are available to create UNIQUE ID's for an application?
I know in ColdFusion we can use CreateUUID() but this generates a string that is very long.
What I want to be able to do is create a string of say no more than 6 characters long that can be considered unique for a number of records that could reach the millions.
For example, the website TinyURL seems to do this quite well with a link like the following:
http://tinyurl.com/dlz23k
How do you think they ensure it's uniqu everytime??
Cheers,
Mikey

Answer 1

I've done quite a bit of research on URL shortening due to a customer's desire. After review of 8th grade math (permutations and combinations), there are two solutions to URL shortening. These schemes assume that the URL cannot be recycled and put back into circulation.
Base 36 - a 6 character URL key consisting of letters a-z and 0-9 for a total of 36 characters, and hence base 36. (26 characters (a-z) and 10 digits). This scheme provides  2,238,976,116 unique URL keys ((36^7-36)/35). Notice, this is case-insensitive. For example, http://foo.com/?ItsMagic and http://foo.com/?itsmagic resolve to the same real URL. If over 2 billion URLs is sufficient, this scheme is for you.
Base 62 - a 6 character URL key consisting of letters a-z, A-Z, and 0-9 for a total of 62 characters (26 +26 + 10 = 62). This scheme provides 57,731,386,986 ((62^7-62)/61) unique URLs. For example, http://foo.com/?ItsMagic and http://foo.com/?itsmagic resolve to DIFFERENT real URLs. If over 5 billion URLs is sufficient, this scheme is for you. (ref: http://www.bennadel.com/blog/1540-Converting-Numbers-To-A-Character-Set-Based-Radix-Using- ColdFusion.htm)
Scheme 1 code:
        <!--- number of times to try getting a unique suffix before quiting --->
        <cfset var tries = 10>
        <!--- current number of trys --->
        <cfset var trycnt = 1>
        <!--- flag that suffix is unique --->
        <cfset var isunique = false>
        <!--- try to generate a random url suffix --->
        <cfloop condition="(not isunique and trycnt lte tries)">
            <!--- number of epoch seconds --->
            <cfset epochs = DateDiff("s", "January 1 1970 00:00", Now())>
            <!--- the suffix is a base 36 number --->
            <cfset suffix = FormatBaseN((RandRange(1,100000000) + epochs),36)>
            <!--- make sure this URL key is unique among those already created --->
            <cfset isunique = URLDAO.isURLUnique(this,suffix);
            <cfset trycnt = trycnt + 1>
        </cfloop>
Scheme 2 code:
See http://www.bennadel.com/blog/1540-Converting-Numbers-To-A-Character-Set-Based-Radix-Using- ColdFusion.htm)