

The "Unknown or expired link" chestnut. Why can't "More" link to ..page=2? - johnmw

I'm sorry, I know this is Hacker News. But isn't part of hacking actually solving problems (aka removing "schlep blindness"?)<p>I've put up with the "Unknown or expired link" message for years.<p>I'm curious - why can't the "More" link just link to news.ycombinator.com/news?page=2 which gives me number #31-60 of the top trending links?<p>I might miss a post or two in the page transition, but if the post is any good I will see it eventually.<p>Just curious.<p>edit: toned the message down a little - it was previously more ranty (which was supposed to be humorous, but some folk might not get that).
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aaronbrethorst
There's an explanation for what you see (the _fnid_ values), here:
<http://news.ycombinator.com/item?id=4899745>

As to why pg can't use normal pagination instead of user-specific state, I
dunno, why not just use Ruby or Python (or PHP!) for the site instead of Arc?
Short answer is, I suppose, because he can, and he's likely more interested in
satisfying intellectual curiosity than designing a normal pagination system.
jm2c.

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lutusp
> As to why pg can't use normal pagination instead of user-specific state, I
> dunno ...

I can think of one reason:

* A user loads the front page.

* By the time the user clicks "More" at the bottom, page 1, and all subsequent pages, have been updated with new content.

* So the server can't provide the old page 2 to a user who just saw the old page 1, for the reason that neither of the original pages even exists any more.

* To avoid confusing the reader, instead of providing an out-of-sync page 2, the server instead shows a "expired link" message.

~~~
aaronbrethorst
I bet that the percentage of people who go to the second page is in the single
digits. Personally, I'd happily trade off a little confusion for a simpler,
more scalable piece of software. That said, it looks like the HN software is
scaling well enough, so more power to the man.

~~~
johnmw
Single digits, eh? Wanna put some hard cash on that bet? ;)

Thanks for the reply, I've replied to this answer (above/below/Unknown or
Expired Link).

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lutusp
> Why can't the "More" link just link to news.ycombinator.com/news?page=2
> which gives me number #31-60 of the top trending links?

1\. HN deals with your interaction by assigning a session index to your
initial contact.

2\. This index allows HN to keep track of which page of which section you're
visiting, so if you click "More" the HN sever knows what do to -- it has a
stored context for your request.

3\. The HN server has limited resources, so if an index goes unused for more
than a few minutes, the server reclaims the index for reuse.

4\. If you wait too long before making a server request like clicking "More",
it's possible that your index will have been reclaimed and assigned to another
user. If this happens, you see the "expired link" message.

5\. After your index has expired and been reclaimed, the HN server has no way
to interpret your command to proceed -- proceed to where?

6\. Also, if you wait long enough, the front page (and all subsidiary pages)
will have changed contents, so the pages you're viewing are no longer current,
consequently the server can't deliver "page 2" for the simple reason that that
version of the page no longer exists.

~~~
johnmw
Thanks for the reply, although I think you are missing my point.

I understand how it works technically, but I think this illustrates a classic
debate between developer and user/customer.

As a developer I can see the functional beauty.

As a user, I think it sucks and I don't give a damn about "session indexes".
As a user I just want to see the next page of cool links. I think most people
here are 'users'. So why not just have a stateless solution? (aka just linking
to ..page=2 as suggested?)

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lutusp
> I think you are missing my point.

The reverse. :)

> So why not just have a stateless solution? (aka just linking to ..page=2 as
> suggested?)

You seem to have missed the point that, if you wait long enough to advance to
page 2, the page that logically follows from the page you're viewing no longer
exists (along with the page you're viewing). In other words, assuming that the
HN content changes between your initial view and clicking "More", the new page
2 may contain what page 1 contained, and people will complain that they're
looking at the same items on page 2 that they viewed on page 1 just five
minutes ago.

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ankitml
I think its ok. Users wont complain. give them a message that the link has
expired just like it is done now. But along with that, serve them the default
/ latest page=2 .

WHy are we debating on 'or' of the option. Expired message or latest page.
None of them alone gives satisfactory use experience. Have them both, tell
them link has expired and serve them default.

~~~
sanchitml
Good solution.

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grandpoobah
Probably for the same reason PG disables user registration when HN has been in
the news.. keeping non-hackers out or something like that.

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lmm
There are browser extensions that fix that. Installing one of them is probably
more practical than trying to get PG to change his mind.

