YouTube URL algorithm?

Question

How would you go about generating the unique video URL\'s that YouTube uses?

Example:

• http://www.youtube.com/watch?v=CvUN8qg9lsk

Answer 1

Eli's link to Jeff's article is, in my opinion, irrelevant. URL shortening is not the same thing as presenting an ID to the world. Instead, a nicer way would be to convert your existing integer ID to a different radix.

An example in PHP:

$id = 9999;
//$url_id = base_convert($id, 10, 26+26+10); // PHP doesn't like this
$url_id = base_convert($id, 10, 26+10); // Works, but only digits + lowercase

Sadly, PHP only supports up to base 36 (digits + alphabet). Base 62 would support alphabet in both upper-case and lower-case.

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People are talking about these other systems:

• Random number/letters - Why? If you want people to not see the next video (id+1), then just make it private. On a website like youtube, where it actively shows any video it has, why bother with random ids?
• Hashing an ID - This design concept really stinks. Think about it; so you have an ID guaranteed by your DBM software to be unique, and you hash it (introducing a collision factor)? Give me one reason why to even consider this idea.
• Using the ID in URL - To be honest, I don't see any problems with this either, though it will grow to be large when in fact you can express the same number with fewer letters (hence my solution).
• Using Base64 - Base64 expects bytes of data, literally anything from nulls to spaces. Why use this function when your data consists of a number (ie, a mix of 10 different characters, instead of 256)?