Visual insight into a basic a-z0-9 'power of' string lengths.

Power of (U)GUID Lengths

If you use your own (U)(G)UID generator for unique identifiers, say UserGUID or WidgetGUID or whatnot, there is very little chance you are ever going to need to use something like `md5(time())` or `bin2hex(random_bytes(5))` or whatever.

Using just a very basic (and all lowercase) `a-z` & `0-9` combination will result in a 36 character string.

abcdefghijklmnopqrstuvwxyz0123456789 = 36 characters

If we take those 36 characters to the `power of` we get the follow possible unique vales:

[1] = 36
[2] = 1,296
[3] = 46,656
[4] = 1,679,616
[5] = 60,466,176
[6] = 2,176,782,336
[7] = 78,364,164,096
[8] = 2,821,109,907,456
[9] = 101,559,956,668,416
[10] = 3,656,158,440,062,976

The average developer is likely to never reach the billion+ widgets/rows so you should safely be able to go with a five (5) character GUID, at the 60-million unique level. If you are one of those few, by all means, check out the list to see just how high these numbers go, without ever introducing capital characters or a single special character.