Question

我正在使用SQL server 2008查询查找距离正在移动的中心点一定距离内的用户 - 这意味着我不断地访问数据库（需要将新结果添加到现有集合中以及要移除的距离）并且保存的每毫秒都是有价值的。

ATM我们正在使用以下查询（使用Id＆＃39;因为它们被索引为ATM并且在尝试速度时很好）：

declare @lat int = 500,
@lon int = 700

  SELECT @lat, @lon, id, journeyid,  ((ACOS(SIN(@lat * PI() / 180) * SIN([Id] * PI() / 180) + 
         COS(@lat * PI() / 180) * COS([Id] * PI() / 180) * COS((@lon - [JourneyId]) * 
         PI() / 180)) * 180 / PI()) * 60 * 1.1515) as dist
FROM [OnlineLegal_dev1].[dbo].[Customer] 
         group by [Id], [JourneyId], ((ACOS(SIN(@lat * PI() / 180) * SIN([Id] * PI() / 180) + 
         COS(@lat * PI() / 180) * COS([Id] * PI() / 180) * COS((@lon - [JourneyId]) * 
         PI() / 180)) * 180 / PI()) * 60 * 1.1515)
HAVING ((ACOS(SIN(@lat * PI() / 180) * SIN([Id] * PI() / 180) + 
         COS(@lat * PI() / 180) * COS([Id] * PI() / 180) * COS((@lon - [JourneyId]) * 
         PI() / 180)) * 180 / PI()) * 60 * 1.1515)<=10000

  ORDER BY ((ACOS(SIN(@lat * PI() / 180) * SIN([Id] * PI() / 180) + 
         COS(@lat * PI() / 180) * COS([Id] * PI() / 180) * COS((@lon - [JourneyId]) * 
         PI() / 180)) * 180 / PI()) * 60 * 1.1515) ASC

选择前1k记录的当前速度为00：00：00.097

我如何才能进一步优化速度？

Answer 1

DECLARE @lat INT = 500,
        @lon INT = 700

DECLARE @lat_s FLOAT = SIN(@lat * PI() / 180),
        @lat_c FLOAT = COS(@lat * PI() / 180)

SELECT DISTINCT @lat, @lon, *
FROM (
    SELECT
        id,
        journeyid,
        ((ACOS(@lat_s * SIN([id] * PI() / 180) + @lat_c * COS([id] * PI() / 180) * COS((@lon - [JourneyId]) * PI() / 180)) * 180 / PI()) * 60 * 1.1515) AS dist
    FROM dbo.Customer
) t
WHERE dist <= 10000
ORDER BY dist

Answer 2

您可以存储预先计算的值

SIN([Id] * PI() / 180)

和

COS([Id] * PI() / 180)

在DB中，例如每次插入或更新Id时都会有INSERT / UPDATE触发器。

CREATE TRIGGER dbo.tiuCustomer ON dbo.Customer
    FOR INSERT, UPDATE
AS BEGIN
   UPDATE dbo.Customer
   SET
       cos_id = COS(Inserted.Id * PI() / 180),
       sin_id = SIN(Inserted.Id * PI() / 180)
   FROM Inserted
   WHERE 
      dbo.Customer.CustomerID = Inserted.CustomerID -- Use the PK to link your table
                                                    -- with Inserted.
END

SQL服务器坐标距离优化

2 个答案: