Ask HN: How should I create a unique id for entries that aren't incremental?

[tim_nuwin]

For example, right now when I'm creating boards (agile), it will create a new board and its id will be n + 1.

What is an efficient way of creating an ID where there won't be any collision even if there are 1 billion+ entries?

This ID will be used in a url..

Thanks, Tim

[smt88]

"where there won't be any collision even if there are 1 billion+ entries"

This is a really complicated topic, and there are multiple ways to handle what you're doing. It really depends on your read/write ratios, typical volume, growth rate, and the underlying DB software you're using.

Because there are so many considerations that require knowing real-world use cases, it's a premature optimization. Are you going to have more than 1 billion records in the next few years? If not, don't worry about this.

However, there are other reasons to use non-incremental IDs (security, for one).

To answer your question as asked though, check this out: http://www.postgresql.org/docs/8.3/static/datatype-uuid.html

[tim_nuwin]

Hmm, well right now users are complaining it's too easy to view other people's boards because the url is https://www.taskfort.com/view/10

The only way to not view a person's board is if it's private.. There are some services that for their pages will have id's that are 7 or so characters long, and very compact, the uuid you're referencing seems kind of ugly.

I would still keep my incremental ID in the table as a PK, but maybe I could generate a new value per row for a public URL ID. That public url id could be based off of their PK but I don't know what would be the best way to generate a short url id w/ the PK as a key.

[iancarroll]

> However, there are other reasons to use non-incremental IDs (security, for one).

That's just security by obscurity, with proper authorization checking it doesn't matter.

[iancarroll]

Incremental IDs work best, but if you want you can hash a UUID which will work for your use case:

% uuidgen

B14818B6-4219-43BD-82EF-8421EC1AFBCF

% echo "B14818B6-4219-43BD-82EF-8421EC1AFBCF" | shasum -a 256

00ea501d47789ac5eb559f10d631b3f6df8f82b5cba9c1f9d234b705d89f1704

[tim_nuwin]

Those urls are kind of ugly. If this helps at all, maybe I could create a public url id based off the incremental PK id's.

[sjs382]

http://hashids.org/

[Rainb]

How about hashing the incremental? Now I wonder how ids like imgur or youtube work.

[Jeremy1026]

Base62 encoded incremental IDs