Databases - String as Primary key? [duplicate]

Question

I develop an application with Laravel 5 and use sqlite during development. I want to switch to something faster later on. I'd like to have a string as unique identifier for the users-table. Is this a problem in any way? For example with foreign keys? Or is there no difference to auto-increment integers?

Answer 1

The short answer : It's perfectly fine to use a string as a primary key.

The long answer : We are terrible at choosing strings to be primary keys.

What is a good primary key candidate ?

1. It should be unique.
2. It should rarely, if at all, change.

Now, You are probably thinking that your string would never change, and that it's extremely unique, Until it will stop being unique.

Another (minor) concern, is performance. Searching, Joining etc. is a bit faster on integers than on strings, mostly due to the length(numbers are normaly shorter than strings, so comparing is easier).

I would think long and hard on what string to use on the primary key, Most of the times it's a bad idea

Answer 2

The indexing of string is a lot different than a incremental int but you can have it as a primary key without problems.

Collision detection when inserting is an issue that you'll have to handle yourself and wouldn't even exist on an auto increment situaiton.

From the foreign key stand point there wouldn't be any problem also, the only problem that you would face is that a char/varchar would be less efficient than an integer.