Question

我正在尝试将表类型传递给存储过程，并希望sproc查找lat / longs的每一行并返回该行的最近点。

类型：

CREATE TYPE dbo.LatLongRoadLinkType AS TABLE
( 
    Id INT NOT NULL,
    Latitude FLOAT NOT NULL,
    Longitude FLOAT NOT NULL
);

存储过程：

ALTER PROCEDURE [dbo].[BatchNearestRoadNodes]
    @Input dbo.LatLongRoadLinkType READONLY
AS
BEGIN
    -- do stuff here
    -- return a table of id from input, nodeid and distance 
END

对于整个表格，这里需要做的是单个纬度/经度：

DECLARE @g geography = 'POINT(13.5333414077759 54.549524307251)';
DECLARE @region geography = @g.STBuffer(5000)

SELECT TOP 1 NodeID, Point.STDistance(@g) as 'Distance'
FROM Location 
WHERE Point.Filter(@region) = 1
ORDER BY Point.STDistance(@g)

Location表有重要的Point类型Geography，它是空间索引的，是比较完成的。我将lat / longs表从代码发送到sproc中，代码期待返回of：

Id (original point passed in)
NodeID (of nearest point in location table)
Distance

我该如何处理？为了让它更容易一点，我可以简单地将SqlGeography从我的代码传递到sproc而不是Lat / Long，但是这会导致性能下降，因为它转换成非常昂贵的。

修改：这有效，但不知道它是否是最佳解决方案。

ALTER PROCEDURE [dbo].[BatchNearestRoadNodes]
    @Input dbo.LatLongRoadLinkType READONLY
AS
BEGIN

SELECT x.Id, x.LocationName, x.NodeID, x.Distance
FROM (SELECT I.Id,
        L.LocationName,
        L.NodeId,
        L.Point.STDistance(geography::Point(I.Latitude, I.Longitude, 4326)) AS Distance,
        ROW_NUMBER ()  OVER (PARTITION BY I.Id ORDER BY L.Point.STDistance(geography::Point(I.Latitude, I.Longitude, 4326)) ASC) AS Ranking
        FROM @Input AS I
        JOIN Location AS L 
        ON L.Point.STIntersects(geography::Point(I.Latitude, I.Longitude, 4326).STBuffer(5000)) = 1
    ) AS x WHERE Ranking = 1
END

效果 - V1与Jon的编辑

V1
============
original:643 found:627 in:1361 ms
original:1018 found:999 in:1700 ms
original:1801 found:1758 in:2628 ms
original:4098 found:3973 in:5271 ms
original:16388 found:15948 in:19624 ms

Jon's Edit
==========
original:643 found:627 in:1333 ms
original:1018 found:999 in:1689 ms
original:1801 found:1758 in:2559 ms
original:4098 found:3973 in:5114 ms
original:16388 found:15948 in:19054 ms

差异很小。需要得到最后一个数字。

Answer 1

尝试这样的方法来获得部分结果：

WITH PreQuery AS
(
I.Id,
GEOGRAPHY::STPointFromText(I.PointAsWKT).STBuffer(5000) AS Geog,
L.NodeId,
L.Point
FROM
@Input AS I
JOIN
Location AS L ON L.Point.STIntersects(I.Geog) = 1
)
SELECT
P.Id,
P.NodeId,
P.Geog.STDistance(P.Point) AS Distance
FROM
PreQuery P

我是从头上写下来的，没有任何测试数据，所以可能会有小错误，但主要是它会给你每个节点和它距离每个点的距离（在5000米内）。你仍然需要过滤它们以获得每个id最小距离的那个 - 不应该太难; - ）

希望它有所帮助，即使不完整。

编辑（12月2日）

我已经看到了我的第一个解决方案的问题，你无法获得距离，因为它是预先缓冲的（注意主要的事情）。但是，这种合并应该是两种尝试的最有效组合。

WITH PreQuery AS
(
SELECT
I.Id,
geography::Point(I.Latitude, I.Longitude, 4326) AS InputGeography
FROM
@input AS I
)
SELECT x.Id, x.LocationName, x.NodeId, x.Distance
FROM
(
SELECT
PQ.Id,
L.LocationName,
L.NodeId,
L.Point.STDistance(PQ.InputGeography) AS Distance,
ROWNUMBER() OVER (PARTITION BY I.Id ORDER BY L.Point.Distance(PQ.InputGeography) ASC) AS Ranking
FROM
Prequery AS PQ
JOIN
Location AS L
-- ON L.Point.STIntersects(PQ.InputGeography.STBuffer(5000)) = 1 -- Slower
ON L.Point.STDistance(PQ.InputGeography) <= 5000 -- Faster
) AS X WHERE Ranking = 1

这样，您只需预先创建输入地理位置一次，而不是根据您的尝试创建三次。这是未经测试的，但应该证明是最有效的。

如何使用Lat Longs的表类型进行批处理STDistance？

1 个答案: