Drupal webform - unique ID for submissions, but unique to THAT form

One of my websites has a LOT of forms, and they are heavily used. This means that t开发者_C百科he Webform module's "SID" is rapidly approaching 1 million, as it notches up a +1 for every form submission across the entire site.

Is there not a form-specific submission ID which starts at 0 for every unique instance of a webform? I've looked at CID, but that seems to be form componant ID?

I guess I could make something to utilise a new SQL table, but it seems crazy this has been overlooked?

You can see here some solutions so submissions are not saved in the database, avoiding the problem http://drupal.org/node/290448