Slow location based search result query - mysql

Question

I have a query that I use to find results that are ordered by location. Results also have to account for VAT so this is also in the query. The query can unfortunately take 4+ seconds to run when not cached. Can anyone spot any glaringly obvious issues or suggest anything I can do to improve it?
Just to clarify what is happening in the query:
The distance is calculation is euclidean distance using lat/long
The incvat fields are used to show the price when vat is included
The WHEN / THEN statement is used to put prices of 0 at the very bottom
The query:
SELECT * , ROUND( SQRT( POW( ( 69.1 * ( company_branch_lat - 52.4862 ) ) , 2 ) + POW( ( 53 * ( company_branch_lng - - 1.8905 ) ) , 2 ) ) , 1 ) AS distance,
hire_car_day + ( hire_car_day * 0.2 * ! hire_car_incvat ) AS hire_car_day_incvat,
hire_car_addday + ( hire_car_addday * 0.2 * ! hire_car_incvat ) AS hire_car_addday_incvat,
hire_car_week + ( hire_car_week * 0.2 * ! hire_car_incvat ) AS hire_car_week_incvat,
hire_car_weekend + ( hire_car_weekend * 0.2 * ! hire_car_incvat ) AS hire_car_weekend_incvat
FROM hire_car
LEFT JOIN company_branch ON company_branch_id = hire_car_branchid
LEFT JOIN hire_cartypelink ON hire_cartypelink_carhireid = hire_car_id
LEFT JOIN users ON company_branch_userid = user_id
WHERE 1
GROUP BY hire_car_id
HAVING distance <=30
ORDER BY CASE hire_car_day_incvat
WHEN 0
THEN 40000
ELSE hire_car_day_incvat
END , distance ASC
LIMIT 0 , 30

Answer 1

You can use the mysql spatial extension and save the latitude and longitude as a point datatype and make it a spatial index. That way you can reorder the coordinates along a curve and reduce the dimension and preserve spatial information. You can use the spatial index as a bounding box to filter the query and then use the harvesine formula to pick the optimal result. Your bounding box should be bigger then the radius of the great circle. Mysql uses a rtree with some spatial index and my example was about a z curve or a hilbert curve: https://softwareengineering.stackexchange.com/questions/113256/what-is-the-difference-between-btree-and-rtree-indexing.
Then you can insert a geocoordinate directly into a point column: http://dev.mysql.com/doc/refman/5.0/en/creating-spatial-values.html. Or you can use a geometry datatype: http://markmaunder.com/2009/10/10/mysql-gis-extensions-quick-start/. Then you can use MBRcontains function like so: http://dev.mysql.com/doc/refman/4.1/en/relations-on-geometry-mbr.html or any other functions: http://dev.mysql.com/doc/refman/5.5/en/functions-for-testing-spatial-relations-between-geometric-objects.html. Hence you need a bounding box.
Here are some examples:
Storing Lat Lng values in MySQL using Spatial Point Type
https://gis.stackexchange.com/questions/28333/how-to-speed-up-this-simple-mysql-points-in-the-box-query
Here is a simple example with point datatype:
CREATE SPATIAL INDEX sx_place_location ON place (location)
SELECT * FROM mytable
WHERE MBRContains
(
LineString
(
Point($x - $radius, $y - $radius),
Point($x + $radius, $y + $radius)
)
location
)
AND Distance(Point($x, $y), location) <= $radius
MySQL latitude and Longitude table setup.
I'm not sure if it works because it's uses a radius variable with a bounding-box function. It's seems to me MBRwithin is a bit simpler, because it doesn't need any argument: Mysql: Optimizing finding super node in nested set tree.

Answer 2

You are using GROUP BY statement together with HAVING, although I don't see anywhere in the query any aggregate functions. I recommend you to re-write the query like this and see if it makes any difference
SELECT * , ROUND( SQRT( POW( ( 69.1 * ( company_branch_lat - 52.4862 ) ) , 2 ) + POW( ( 53 * ( company_branch_lng - - 1.8905 ) ) , 2 ) ) , 1 ) AS distance,
hire_car_day + ( hire_car_day * 0.2 * ! hire_car_incvat ) AS hire_car_day_incvat,
hire_car_addday + ( hire_car_addday * 0.2 * ! hire_car_incvat ) AS hire_car_addday_incvat,
hire_car_week + ( hire_car_week * 0.2 * ! hire_car_incvat ) AS hire_car_week_incvat,
hire_car_weekend + ( hire_car_weekend * 0.2 * ! hire_car_incvat ) AS hire_car_weekend_incvat
FROM hire_car
LEFT JOIN company_branch ON company_branch_id = hire_car_branchid
LEFT JOIN hire_cartypelink ON hire_cartypelink_carhireid = hire_car_id
LEFT JOIN users ON company_branch_userid = user_id
WHERE ROUND( SQRT( POW( ( 69.1 * ( company_branch_lat - 52.4862 ) ) , 2 ) + POW( ( 53 * ( company_branch_lng - - 1.8905 ) ) , 2 ) ) , 1 ) <= 30
ORDER BY CASE hire_car_day_incvat
WHEN 0
THEN 40000
ELSE hire_car_day_incvat
END , distance ASC
LIMIT 0 , 30