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

Here's a few ideas, some of which may not apply depending on your exact situation.

1. You could do the conversion of latitude and longitude to radians and store that in the row as well. This would save the cost of those calculations (actually the cost would be accrued once when storing the data).
2. If your table is very large, you could use a simple linear distance calculation rather than the Haversince formula to limit the results to which you apply the Haversince formula.
3. If you have other data in the table that would serve as a good first filter (country/region/etc.), you could apply it first.
4. You could reorder your joins so that they are applied after the distance filter so that you don't incur the cost of the join on data that doesn't qualify.