[geos-devel] [GEOS] #982: Postgis ST_ConcaveHull Runtime GEOS Problem?

GEOS geos-trac at osgeo.org
Sun Aug 25 07:52:27 PDT 2019

#982: Postgis ST_ConcaveHull Runtime GEOS Problem?
 Reporter:  tsw         |       Owner:  geos-devel@…
     Type:  defect      |      Status:  reopened
 Priority:  major       |   Milestone:
Component:  Default     |     Version:  3.7.0
 Severity:  Unassigned  |  Resolution:
 Keywords:              |

Comment (by tsw):

 I've further tested this today and calls to public.ST_UnaryUnion in
 ST_Concave hull don't make any difference as they are only applied to
 polygon geometries, and in this case, lines are the problem.

 HOWEVER, the ST_UnaryUnion call made at the end of _st_concavehull added
 in response to issue 3638 is the source of this problem. If this is
 commented out the query runs instantly. Not sure if there is another way
 to address 3638, but this change causes the slowdown I document here.

Ticket URL: <https://trac.osgeo.org/geos/ticket/982#comment:6>
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GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).

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