how to get the nearest 100 points from one million data records quickly?

Question

given one point A, get the nearest 100 points from one million data records

• database is MySql
• one million records of latitude and lon

Answer 1

1. Setup spatial extensions for your database, if you have not done that already.
2. Store latitude/longitude of your 1M locations in a geography-type column in the database.
3. Create a spatial index on that column.
4. Run a SELECT query with a WHERE clause based on distance between your point of interest and locations in the table. The query will utilize the above index.

Here is a good article on using spatial extension in MySQL 5.6 for exactly this sort of things.

Answer 2

http://en.wikipedia.org/wiki/Geohash might be a quick way to speed up the average case, but worst case behaviour would still be bad. The article suggests that you index by geohash and, on a query, retrieve all points in a bounding box that amounts to a geohash prefix. If the bounding box is small and you find a match in it closer than any point outside the bounding box then you have succeeded quickly, but neither of these things might be true.