patrick.net

@stereotomy @MolotovCocktail

OK, I've fixed the thing with the new comment. It should show up as the last comment on a page now, with other comments before it.

I'm still observing the same behavior. Right now in this thread all I see is post #1 and #695.

its weird, first time clicking into a thread I only see one comment, happens a lot.

Hold on - after I posted my last comment, things seem to be fixed. Thanks!

EDIT: Things only appear normal right after I post a new comment to a thread. If I view new comments without posting or editing, all I see is the first and last comments. This includes viewing my most recent comment once I step away from the thread.

I always just see one comment.

Huh, I now have url options to view 40 before a given comment, or 40 starting at a given comment, or 40 after a given comment, or just the last page of comments.

Say there is a single new unread comment on a thread, and you click on that thread on the home page.

If I choose before that unread comment, you see 40, but not that one.
If I choose starting at that unread comment, that's the only one you see, because there's only one unread comment.
If I choose after that unread comment, there is nothing there.
If I choose last page, that would work for that single comment case, showing you the whole last page... except then if you're trying to read an unread comment is more than 40 before the last comment, then now that case would be broken.

OK, if an unread comment is more than 40 before the last comment, then I should use start at.
But if there are fewer than 40 before last comment, then show last page.

I'll see if I can do that.

FortWayneHatesRealtors says

its weird, first time clicking into a thread I only see one comment, happens a lot.

I saw that about an hour ago, too.

OK, fixed now?

What this site mostly does is select a window of a sparse subset of the comments table. That spares subset could be:

- all the comments on a thread
- all the comments by a user
- all the comments matching a search

It was getting painfully slow to view comments in a large result set because the URLs were using the ordinal number in the total result set to select which window of comments to show. Calculating those ordinal numbers required sorting every row in the comments table, which now has 1.3 million comments.

The new way is to use comment_ids in the URLs. That lets me select ranges, which is way faster. So now if you page through some thread or some user's comments, it should be 10x faster.

But working with comment_id's instead of "nth to mth comment in total result set" forced me to rework tons of code, resulting in unforeseen problems like the ones above.

I think that did it. Thanks Patrick!