yeah my bad I was looking through the wrong source. Do you do anything special for point queries, e.g. what town is this point in, which geohashes tend not to be that great for (in my experience)
Nothing special. We use S2 to compute a covering of a polygon (like a town) by a number of grid cells. If you insert a polygon (or line) into a geospatial index, it will actually be inserted multiple times, with one entry for each grid cell of its covering. Then when you query by a point (e.g. to answer said query, assuming you have a table with all the town polygons), we find any polygon that has a grid cell that intersects with that point and then do a post-filtering check using the actual detailed geometry of the candidate polygon. This is fairly efficient and can be extended to a lot of different cases, though I'm sure there are more efficient specialized data structures for some specific types of queries.
