Question

I wonder why many web sites choose to use random id:s instead of incrementing from 1 on their database tables. I´ve searched without finding any good reasons, are there any?

Also, which is the best method to use? It seems quite inefficient to check if an id already exists before inserting the data, (takes a second query).

Thanks for your help!

Answer 1

Under the hood, it is likely that they are using incremental ids in the database to identify rows, but the value that gets exposed to end users via the URL parameters is often made into a random string to make the sequence of available objects harder to guess.

It is really a matter of security through obscurity. It hinders automated scripts from proceeding through incremental values and attempting attacks via the URL, and it hinders automated scraping of site content.

If youtube, for example, used incremental ids instead of values like v=HSsdaX4s, you could download every by simply starting at v=1 and incrementing that value millions of times.