Does Hacker News sort trending topics on-the-fly or as a scheduled task?

[mcassagnes]

I'm interested to know how they deal with massive amounts of data and still deliver blazing fast results. When I go to https://news.ycombinator.com/, are the threads sorted on-the-fly or pre-computed every x minutes? I found lots of information regarding the actual algorithm, but not how it is implemented.

[dang]

It reranks items incrementally.

I'd love to get to the point where we can sort everything on every request.

[mcassagnes → dang]

Do you have any source for this? I'd love to know more about how they re rank items incrementally.

Do they actually update every single row in the database every 5 minutes? It seems too slow.

[snowwrestler → mcassagnes]

Source: dang is one of the employees of Y Combinator who help run HN.

Dang--might be good to have some way to indicate that so new folks understand your special role in the community here

[dangrossman → mcassagnes]

HN doesn't use a database. There are no rows. Just one process on one server with everything in memory. Data is lazy loaded from flat files on-demand.

[krapp → dangrossman]

I assumed that in memory they had something structurally resembling a relational database but they might not. It would never even occur to me to not use a database for something like this.

[mcassagnes → dangrossman]

Thank you. I did not expect that!