按最近的顺序排列 - PostGIS,GeoRuby,spatial_adapter

Question

我正在尝试执行查找最接近current_user的记录的订单查询.

我知道这两点之间的距离是: current_location.euclidean_distance(@record.position)

如何将其用于PostGIS(或active_record/spatial_adapter)查询？

Answer 1

要获得最接近的5个:

SELECT * FROM your_table 
ORDER BY ST_Distance(your_table.geom, ST_Geomfromtext(your point as wkt)) 
limit 5;

如果您有一个大数据集,并且知道您不想进一步搜索,比如1 km,那么如果您执行以下操作,查询将更有效:

SELECT * FROM your_table 
WHERE ST_DWithin(your_table.geom, ST_Geomfromtext(your point as wkt, 1000)
ORDER BY ST_Distance(your_table.geom, ST_Geomfromtext(your point as wkt))  
limit 5;

/尼克拉斯

Answer 2

以防万一有人在rails 4中偶然发现这个问题.我正在使用rgeo gem,这对我有用

scope :closest, ->(point) { order("ST_Distance(lonlat, ST_GeomFromText('#    {point.as_text}', #{SRID}))").limit(5) }