[英]Why is PostGIS stacking all points on top of each other? (Using ST_DWithin to find all results within 1000m radius)
[英]Using a Postgres array[] filled with PostGIS WKB coordinates results in “function st_dwithin(text, geometry, integer) is not unique”
我正在使用Postgres 9.1和PostGIS 2。
示例查询不起作用 :
SELECT
*
FROM measurement m
JOIN (SELECT unnest(array['002000000100000000404ff25e353f7cee401d01da7b0b3919']) AS p) AS ps
ON ST_DWithin(ps.p, m.groundtruth, 5)
示例查询有效 :
SELECT
*
FROM measurement m
JOIN (SELECT 1) AS foo
ON ST_DWithin('002000000100000000404ff25e353f7cee401d01da7b0b3919', m.groundtruth, 5)
这也可行 :
SELECT unnest(array['002000000100000000404ff25e353f7cee401d01da7b0b3919'])
但是,当然,我需要数组正常工作的查询。
我从Rails调用此查询,该查询会自动插入WKB格式(意味着:如果重要的话,我不知道如何将其更改为WKT)。
完整的示例Rails代码如下所示:
x = [RGeo::Geos.factory.point(63.8935, 6.25181)]
@measurement = Measurement.find_by_sql([radius_search_query, x])
def radius_search_query
SELECT
*
FROM measurement m
JOIN (SELECT unnest(array[?]) AS p) AS ps
ON ST_DWithin(ps.p, m.groundtruth, 5)
end
但是我也从上面测试了该查询(不使用?
),并且由于相同的错误消息而不断失败:
ERROR: function st_dwithin(text, geometry, integer) is not unique
LINE 5: ON ST_DWithin(ps.p, m.groundtruth, 5)
^
HINT: Could not choose a best candidate function. You might need to add explicit type casts.
我以为我可能不得不告诉数组它是geometry
类型而不是text
类型(如错误消息中所示)。 但是我还没有找到一种方法。
谢谢!!
这不起作用:
SELECT
*
FROM measurement m
JOIN (SELECT '002000000100000000404ff25e353f7cee401d01da7b0b3919' as bar) AS foo
ON ST_DWithin(foo.bar, m.groundtruth, 5)
错误消息: failed to find conversion function from unknown to geometry
这有效:
SELECT
*
FROM measurement m
JOIN (SELECT '002000000100000000404ff25e353f7cee401d01da7b0b3919'::geometry(Point) as bar) AS foo
ON ST_DWithin(foo.bar, m.groundtruth, 5)
在我找到一种解决方案后,使查询变得非常慢(由于强制转换值):
SELECT
*
FROM measurement m
JOIN (SELECT unnest(array['002000000100000000404ff25e353f7cee401d01da7b0b3919']) AS p) AS ps
ON ST_DWithin(ps.p::geometry(Point), m.groundtruth, 5)
我环顾四周,偶然发现PostGIS的linestring
。 现在一切正常!
SELECT
*
FROM ST_DumpPoints('00200000020000000000000002404ff25e353f7cee401901da7b0b3919404ff25e353f7cee401d01da7b0b3919') AS ps
JOIN measurement m
ON ST_DWithin(ps.geom, m.groundtruth, 5)
好极了! :-)
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