Question

I have a table with structure like that:

table name: shop

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

And I’d like to calculate distance between given coordinates and coordinates saved in database.

My current query:

SELECT *
  FROM `shop` AS `s`
 WHERE
      (
        ( 6371
        * ACOS(
            SIN( RADIANS( latitude ) )
          * SIN( RADIANS( 53.5353010379 ) )
          + COS( RADIANS( latitude ) )
          * COS( RADIANS( 53.5353010379 ) )
          * COS( RADIANS( 14.7984442616 ) - RADIANS( longitude ) )
          )
        )
        <= 25
      )

plus some JOIN LEFT‘s for some data.

Is there any way to optimize that query ?
With joins it takes about 13msec.

I need to add here also some LIMIT and COUNT(*) for total amount of shops for pagination.

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.