slug - when to store slugfield in database in django? -

suppose access article at

/article/23/the-46-year-old-virgin 

in /article/id/slug form.

i can use id fetch data in view.
don't see reason store slug in database.

besides, /article/id/slug isn't better /article/slug ?

the problem using id hurt both url readability , search engine optimization. (see here latter.)

one problem using slug long , urls truncated in real world. if have id @ beginning use lookups , redirect if went wrong slug part. other problem have guarantee slugs unique. sure you'll never want have 2 articles same title?

so doing 1 or other possible, there benefits doing both.

as whether or not should store slug in database, first decide if want url change when title changes. 1 advantage keeping same have single, permanent, canonical url resource, 1 won't change if need edit title. obvious downside url no longer reflect exact title of article.

if want slug match title, becomes standard database denormalization question - slug represent redundant (derived) information you're precomputing performance reasons. wouldn't bother, myself.

if want url stay same if title edited, of course have store slug separately.