I wrote a little post on how Redis works and its various setups! How does everyone setup Redis? Elasticache is a good answer too :P
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It's a new article so it's relatively easy to explain:
HN automatically combines submissions so that subsequent submissions count as upvotes for the first submission.
If a popular source posts a new article, users will "rush" to post it to HN to reap that sweet karma and the winner will "catch" the upvotes of the others.
That could explain it. Thanks!
Is this behavior documented anywhere on news.ycombinator.com?
https://news.ycombinator.com/newsguidelines.html
and
https://news.ycombinator.com/newsfaq.html
and a handful of posts by dang, sama, pg, etc. over the course of the years. most of the rest is what long-time users have just figured out through observation. There's a Git repo[1] out there that aggregates a lot of that stuff, but keep in mind that it's technically unofficial. That said, I think most of what's there is widely considered to be correct.