所有商户都有GPS坐标。当给定一个坐标，计算出离给定坐标最近的10个商户，并可再次搜索（再搜时需排除原已搜过的）。

提取算法，数据结构，缓存，存储方式，设计思想？

FIELD TYPE COLLATION NULL KEY DEFAULT Extra PRIVILEGES COMMENT
testId INT(11) (NULL) NO PRI (NULL) AUTO_INCREMENT SELECT,INSERT,UPDATE,REFERENCES 编号
testName VARCHAR(64) utf8_general_ci NO (NULL) SELECT,INSERT,UPDATE,REFERENCES
testLongitude DOUBLE (NULL) YES (NULL) SELECT,INSERT,UPDATE,REFERENCES 经度
testLatitude DOUBLE (NULL) YES (NULL) SELECT,INSERT,UPDATE,REFERENCES 纬度
testLatitude DOUBLE (NULL) YES (NULL) SELECT,INSERT,UPDATE,REFERENCES 纬度
createTime DATETIME (NULL) NO (NULL) SELECT,INSERT,UPDATE,REFERENCES

获取某经纬度附近dist km的商户信息，肯定要区分商户类别、经纬度、开始记录、记录数量、范围距离

DROP PROCEDURE IF EXISTS pro_getNearUser
CREATE PROCEDURE pro_getNearUser(IN mylon DOUBLE,IN mylat DOUBLE,IN begin INT,IN counts INT,IN dist INT)  
BEGIN  
  DECLARE mylon DOUBLE;  
  DECLARE mylat DOUBLE;   
  DECLARE lon1 FLOAT;  
  DECLARE lon2 FLOAT; 
  DECLARE lat1 FLOAT; 
  DECLARE lat2 FLOAT;  
  -- calculate lon and lat for the rectangle:
  SET lon1 = mylon-dist/ABS(COS(RADIANS(mylat))*69);  
  SET lon2 = mylon+dist/ABS(COS(RADIANS(mylat))*69); 
  SET lat1 = mylat-(dist/69);   
  SET lat2 = mylat+(dist/69);
  -- run the query:
  SELECT  merchantId,3956 * 2 * ASIN(SQRT(  POWER(SIN((orig.userLon - dest.userLat) * PI()/180 / 2), 2) +  
  	COS(orig.userLat * PI()/180) * COS(dest.userLat * PI()/180) * 
  	POWER(SIN((orig.userLon -dest.userLon) * PI()/180 / 2), 2)  )) AS distance 
  FROM  users dest,  users orig 
  WHERE  dest.userLon BETWEEN lon1 AND lon2  AND  dest.userLon BETWEEN lat1 AND lat2 
  HAVING distance < dist 
  ORDER BY distance 
  LIMIT begin,counts;  
END