How to optimize SQL query with calculating distance by longitude and latitude?

Question

I have a table with structure like that:

table name: shop

id_shop      int(10)
name         varchar(200)
latitude     double
longitude    double
         


        

Answer 1

Well, for starters, you could store pre-calculated stuff in the database when you store the latitude and longitude. If you pre-store the latitude and longitude as radians, for example, you'll only need to calculate RADIANS(latitude) and RADIANS(longitude) once, when you store each location, not every time you need to do your distance calculation (presumably far more than once.)

Maybe shave off a bit more by storing the SIN(RADIANS(latitude)) and COS(RADIANS(latitude)) when you first populate the row, too...

I'm guessing you're doing many, many "nearest thing to X" calculations over time -- that's what people are generally doing when faced with this calculation -- and pre-calculating what you can is normally the first thing to try.