Question

I am little bit confused about following problem & their solutions:
i have 2 tables users & userfriends having following structure

users
userid         lat          long


userfriends
    userid         friendid

so in users table i have lat & long of all the users & in userfriends i have list of friends for each user.
Now i want to calculate nearby users (distance) so my friend told me to use mongodb which have fast performance.
But i found another function which i can use in stored procedure in mysql

function distance($lat1, $lon1, $lat2, $lon2, $unit) { 

  $theta = $lon1 - $lon2; 
  $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta)); 
  $dist = acos($dist); 
  $dist = rad2deg($dist); 
  $miles = $dist * 60 * 1.1515;
  $unit = strtoupper($unit);

  if ($unit == "K") {
    return ($miles * 1.609344); 
  } else if ($unit == "N") {
      return ($miles * 0.8684);
    } else {
        return $miles;
      }
}

So basically i want my distance calculation faster & quick.
So can somebody tell me am i correct in my way or i need to send needed data (lat & long of users friends) to mongodb & calculate & mongodb will return results to my database (MySQL)?

Answer 1

Both MySQL and MongoDB support geospatial indexing. IME, NoSQL databases have huge performance advantages when dealing with selecting individual records, but offer less of a performance benefit (still usually faster) compared with a relational database when dealing with range queries – YMMV.

There are other very fundamental differences – which are well covered elsewhere.

You really want to spend a lot of time reading the linked documents – the method you describe will be phenomonally innefficient.