Comments on: No space

By: Kenny Kerr

Kenny Kerr — Thu, 01 Jun 2006 00:56:50 +0000

Exactly. I think that’s what I was trying to say.

By: Paul Watson

Paul Watson — Thu, 01 Jun 2006 00:00:57 +0000

Thanks for the info, Kenny. None of these considerations are helping the user though, just us developers which is the wrong, but common, way.

By: Kenny Kerr

Kenny Kerr — Wed, 31 May 2006 23:42:14 +0000

The main reason certain characters aren’t allowed in user names is to allow parsing – either for subtext searching or for breaking a user name into parts (e.g. principal and authority). I wrote briefly about handling Windows credentials in 2004 (http://weblogs.asp.net/kennykerr/archive/2004/0...). Another common reason is to allow user names to be used in file system paths for example in the user profile directory path. Of course if you’re building a custom authentication system backed by a database there’s no reason to limit characters or length. Limiting length is also not very useful. If you have relatively few users (hundreds) then you’re not going to save much space or time with short user names. If you have relatively high numbers of users (thousands or millions) then you’re going to force users to create silly user names like paul1234. The main limitation is ensuring that the user name can be used as an indexed key in a database but then the limitation even for Unicode usernames would still be as high as 400 characters depending on the database engine.

By: Kenny Kerr

Kenny Kerr — Wed, 31 May 2006 19:56:50 +0000

Exactly. I think that’s what I was trying to say.

By: Paul Watson

Paul Watson — Wed, 31 May 2006 19:00:57 +0000

Thanks for the info, Kenny. None of these considerations are helping the user though, just us developers which is the wrong, but common, way.

By: Kenny Kerr

Kenny Kerr — Wed, 31 May 2006 18:42:14 +0000

The main reason certain characters aren’t allowed in user names is to allow parsing – either for subtext searching or for breaking a user name into parts (e.g. principal and authority). I wrote briefly about handling Windows credentials in 2004 (http://weblogs.asp.net/kennykerr/archive/2004/07/09/178435.aspx). Another common reason is to allow user names to be used in file system paths for example in the user profile directory path. Of course if you’re building a custom authentication system backed by a database there’s no reason to limit characters or length. Limiting length is also not very useful. If you have relatively few users (hundreds) then you’re not going to save much space or time with short user names. If you have relatively high numbers of users (thousands or millions) then you’re going to force users to create silly user names like paul1234. The main limitation is ensuring that the user name can be used as an indexed key in a database but then the limitation even for Unicode usernames would still be as high as 400 characters depending on the database engine.