I was thinking about how to make a small function that generates a YouTube-like ID and does not cause collisions. The charset should be A-Za-z0-9-_ and lets say I want it to be 10 characters long which would equal 64 ^ 10 / Quadrillion - 1153 Quadrillion possibilities.
It's rather important to be small due to the fact that it's one of the major functionality of the website and should be clear enough to be modified easily. Within seconds in case an emergency occurs.
It doesn't have to be secure in the sense that we don't really mind whether it's easily to convert back to an ID as an outsider. It should however not be a pattern such as:
aaaaaaaaaa
aaaaaaaaab
aaaaaaaaac
I'm aware that you could theoretically make a charset and loop through it randomly until you have 10 random characters but this could collide ( I realize this chance is slim and you could perform a query to see whether the key has been generated before but I would like to keep dependencies minimal and it not relying on SQL ).
I can also imagine making a charset of 100 characters as in 0-99 and then prepend and/or append random characters if the length of 10 condition is not met. Eg:
- IMPORTANT: the scenario sketched below assumes
Ais the first character in the set and_is the last one.
id: 0 = A+9 random characters
id: 1 = B+9 random characters
id: 99 = _+9 random characters
id: 990 = _A+8 random characters
id: 99999999999999999999 = __________
I would think that would prevent collisions but I don't have a charset of 100 but 64.
Hope someone can toss some ideas.
- UPDATE1: The above sketch could actually collide in the following (and more) circumstance(s):
If the
IDis99it doesn't mean that the next character can't beAbychancealthough very unlikely; it could thereforecollidewith990:-(UPDATE2: I don't think it would still collide if we use a
static componentafter theIDand before therandom componentthat is not part of thecharset.Updated Sketch (the static component will be $):
