Ask PG: How often are the ratings for HN submissions crunched

6 pointsmonological3 comments

I was just curious how it's implemented.

I know the formula is:

(p - 1) / (t + 2)^1.5

where p and t are:

p = votes (points) from users. t = time since submission in hours.

So to reduce the load on the server, is the calculation done every X number of minutes? Then when you query for the stories, do you just sort by rating desc?

View on HN

It's done per story when one's score changes after a vote, and also occasionally for random stories near the top. See the source.

I think the equation needs to be tweaked a bit, honestly. Some of these stories that get 100+ votes stay on the front page for longer than they really should, taking up space that many other interesting, yet less popular, stories could occupy.

Yeah, you're probably right. There are now so many more votes on the top stories that they do stay around longer than they used to. I just increased gravity to 1.8 and the frontpage looks better now.

Reply on news.ycombinator.com