geohashing - Geohash：多少哈希长度就足够了

Question

对于需要以 Geohash 形式存储人的地理位置的应用程序，多少哈希长度（以字符为单位）就足够了？

位于此处的代码（参见维基百科关于Geohash的文章）说：

    #define MAX_HASH_LENGTH 22

但他们没有提到任何原因。

Answer 1

可以在其他主题上找到一些理由：

地理哈希和最大距离

geohash 字符串长度和准确性

要定位一个人，您可能需要一米的精度。10 个字符应该足够了。

Answer 2

If you are looking at something like building or house locations (associated with a person) you could go as small as geohash of length 8.

A geohash with a string value of 8 characters gets you to within +/- 20 meters of a location, a geohash of 9 characters gets you with +/- 5 meters. See a full list of information on geohash lengths on wikipedia