Fastest Way to Find Distance Between Two Lat/Long Points

Question

I currently have just under a million locations in a mysql database all with longitude and latitude information.

I am trying to find the distance between one point a

Answer 1

I needed to solve similar problem (filtering rows by distance from single point) and by combining original question with answers and comments, I came up with solution which perfectly works for me on both MySQL 5.6 and 5.7.

SELECT 
    *,
    (6371 * ACOS(COS(RADIANS(56.946285)) * COS(RADIANS(Y(coordinates))) 
    * COS(RADIANS(X(coordinates)) - RADIANS(24.105078)) + SIN(RADIANS(56.946285))
    * SIN(RADIANS(Y(coordinates))))) AS distance
FROM places
WHERE MBRContains
    (
    LineString
        (
        Point (
            24.105078 + 15 / (111.320 * COS(RADIANS(56.946285))),
            56.946285 + 15 / 111.133
        ),
        Point (
            24.105078 - 15 / (111.320 * COS(RADIANS(56.946285))),
            56.946285 - 15 / 111.133
        )
    ),
    coordinates
    )
HAVING distance < 15
ORDER By distance

coordinates is field with type POINT and has SPATIAL index
6371 is for calculating distance in kilometres
56.946285 is latitude for central point
24.105078 is longitude for central point
15 is maximum distance in kilometers

In my tests, MySQL uses SPATIAL index on coordinates field to quickly select all rows which are within rectangle and then calculates actual distance for all filtered places to exclude places from rectangles corners and leave only places inside circle.

This is visualisation of my result:

Gray stars visualise all points on map, yellow stars are ones returned by MySQL query. Gray stars inside corners of rectangle (but outside circle) were selected by MBRContains() and then deselected by HAVING clause.