Re: Optimised way to search over 2 milllion poi data in mysql

[newbie Shai]

Dear Rick,
I need some more clarification here.

1.DECLARE _deg2rad DOUBLE DEFAULT PI()/1800000; - this is need to change my current lat and long into radian is it ?

2. Why do we set this SET @deg2dist := 0.0069172, -- 69.172 for miles; 111.325 for km *** (mi vs km) and not just use as 69.172 ?

3. I am also not to clear why this is needed @lon2lat := COS(_deg2rad * @my_lat), ?

4. Why I cant use the @dlon to be as @dlat not too clear on it.

I am trying to grasp the whole thing getting closer with the idea now.