[postgis-tickets] [PostGIS] #5401: ST_Difference silently giving us wrong results

PostGIS trac at osgeo.org
Wed Jun 14 14:21:38 PDT 2023


#5401: ST_Difference silently giving us wrong results
--------------------------------+---------------------------
  Reporter:  Lars Aksel Opsahl  |      Owner:  pramsey
      Type:  defect             |     Status:  new
  Priority:  medium             |  Milestone:  PostGIS 3.3.4
 Component:  postgis            |    Version:  3.3.x
Resolution:                     |   Keywords:
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Comment (by pramsey):

 I just pulled up PostGIS under 3.11 and I also didn't see precision
 reduction artefacts there either, using the
 {{{
 CREATE TABLE difference_test_01 AS
 SELECT (ST_Dump((ST_Difference(pt.geo,u.geo)))).geom AS geom FROM
 ( SELECT ST_Collect(distinct pt.geo) AS geo FROM all_area pt WHERE
 ST_IsValid(pt.geo)) AS pt,
 ( SELECT ST_Union(geo) AS geo FROM used_area u WHERE ST_IsValid(geo) ) AS
 u;
 }}}
 formula to test.
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5401#comment:12>
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