[lainga]

How big of a problem is the fact that shards constructed this way don't like crossing the "big" boundaries in the S2 curve? Especially if a high-usage location happens to straddle one of those boundaries (like, IIRC, Toronto)?

[lixtra]

You can compute which shard to use and if you’re in a border region you just use all shards that overlap with your 100km radius.

[throwaway080383]

Yeah it seems like the real bottleneck is that in these super dense areas, there might be a ton of shards in a mid-size radius. This is inevitable since in the middle of Manhattan, there are just a lot of people in a small area.

One solution would be to scale their recommendation radius with density; no need to look farther than 5 miles for true love in Manhattan, but in Wyoming you may have to drive a bit.

[peteretep]

The flip side though is that you don't need to show everyone to everyone, you just need to make sure people have enough other people to swipe. This opens up all sorts of other optimizations, and makes the use of an actual search engine seem a bit weird to me.

[lainga]

That's tragic! What if the love of your life is on the other side of the Hilbert curve, fated never to meet?

[gregoriol]

Actual search engine is needed by other criteria like age range I would say. They also have things priority and maybe plan for more.