Sorry for the slow-down in the last 36 hours. There was a database issue. Recommendations weren’t being cached right, so it had to remake them every time. That took a lot of processing power. For example, to produce a recommendation for one of the Harry Potter books it had to retrieve and do math on the libraries of nearly half of of all LibraryThing! And when a page doesn’t come up immediately many users hit refresh over and over—the spiral of death.

I fixed the immediate problem, but it will be a little while before the cache is full again. I’m going to fix the larger problem by adding a second, “thinking” server, that will get a new copy of the book data ever night and sit around all day thinking about recommended books, related tags and so forth. LibraryThing’s slowness—when it’s slow—is all about these tasks. Looking at your catalog, adding books and so forth don’t tax it much. I also like the idea of a server that sits around all day thinking about books. It might even develop opinions.

Finally, I’m going to make some more tweaks at 3am EST tonight. This means that people in California will not be able to add books while watching Dick Clark’s New Year’s Rockin’ Eve. For this I apologize.

I’ve made a new feature to make tagging your books easier. You can now edit the tags within your catalog without having to “go into” each book individually.

The tag list now includes a link to “edit.”

Click “edit” and type your changes into the box that pops up. When you submit it both changes the screen and the database without leaving or refreshing the page.

“Ajax-tastic”? Programming and “Web 2.0” junkies will recognize this as “Ajax,” a term that is supposed to mean “Asynchronous JavaScript and XML” but has come to mean “changing the page without refreshing it” or “acting more like a desktop ap.” Expect to see more of this sort of thing.

Bugs? As with most new features, my ears are open for problems. I tested it, but not on every possible browser/OS combination (memo to self: buy ten computers). And people end up doing things I never anticipated. So, for the next day or so, treat it as a beta feature. Don’t change 100 tags without checking whether the edits are “sticking.”

Ideas? In theory, I could make every field editable this way. But I’m concerned about a cluttered user interface. What do you think?

I’m taking the site down for an hour at 3am EST (9:00 GMT). With luck, I’ll have some new features to announce shortly!

If you want to share your holiday loot, consider using tags like Christmas 2005, xmas05, Chanukah 2005, etc. We’ll tag combine and compare notes!

Christmas presents from the Mainstream Media! PCWorld’s February issue (on the web, if not the newsstands) has a feature article Scott Spanbauer “New, Improved Web,” on “Web 2.0” applications. The “Collaboration & Community” section covers companies like Flickr, Del.icio.us, Facebook—and LibraryThing!

“For book lovers, it’s a LibraryThing: This site is similar to Del.icio.us, but for the tweed set. If you love books, and love people who love books, LibraryThing is for you. Start by using the service to catalog your book collection: Tag your books by topic, share your catalog with others, and then endlessly browse the titles that they have on their shelves. The utterly book obsessed can add the LibraryThing widget to a blog to show visitors what they have been reading lately. Listing up to 200 books is free; listing any number of books beyond that costs either $10 per year or a one-time $25 fee.”

Except for the part about the “tweed set”—are readers as marginal as that?—that’s pretty sweet.

In related news, LibraryThing has been picked up by a third Welsh-language blog (see the buzz page). It makes more sense than you might think; the National Library of Wales is one of the 30+ libraries LibraryThing accesses. And the Welsh are big readers—Hay-on-Wye, the world’s greatest bookstore-town is located there. And they probably wear tweed a lot too.

(Hat tip to Steve Cohen’s LibraryStuff for the link.)