Oh, I see. One word is that the Polls is a topic with some fixed options item providing users to chose. Being One of HN item type. To Poll of HN, may be that database table is legacy feature designing.

If nothing else, the production of this web page is really wonderful.

When a user is visiting that URL, the web will show some issues. Are there any things to resolve it? will HN delete that post?

If it's invalid at the time of the submission: Someone may post a comment warning the OP or try finding the correct URL. Sometimes the mods change the URL, or the OP may post the correct one in a new thread. But if it's not fixed, most of the times it will get flagged and dead.

It it get's invalid after some time (let's say more than a week): Probably nothing. It will be a bad link forever.

Yeah, I see. For operation of flag, is by HN or unactive naturally?

Readers flag stuff. Possibly needs certain karma level, I forget.

OKay, that 's good feedback mechanism. thx.