Hi, There were changes ST_ConcaveHull that fixed robustness of it in 2.2 -> 2.5 chain. To point where the penalty comes from, try to run a query and on a side console server-side run `sudo perf top`. Function names will get you a rough idea where the execution process lives now.
To further debug, go to blame view in github and try updating st_concavehull (it's in SQL) change by change. Most recent adds an union here, try commenting it out and hot reloading on your db. https://github.com/postgis/postgis/blame/svn-trunk/postgis/postgis.sql.in#L6155 Can you share the data and ticket this on http://trac.osgeo.org/postgis/? What is the data structurally? Are these 6000 objects points, or polygons? On Fri, Aug 2, 2019 at 3:43 AM Trevor Wiens <tsw....@gmail.com> wrote: > I am having difficulty determining why I'm seeing significant differences > in performance between two database configurations with the same data. > > One one machine (centos) I have the following software: > geos 3.5.0 > sfcgal 1.3.1 > cgal 4.7.1 > postgis 2.2 > postgresql 9.4 > > On a second machine (debian 10) I have the following: > geos 3.7.1 > sfcgal 1.3.6 > cgal 4.13 > postgis 2.5.2 > postgresql 9.6 > > In terms of hardware there is no significant difference, if anything the > second machine is more capable, but that is not reflected in my performance > results. > > On the first machine when I run a ST_ConcaveHull with about 6000 features, > I get result a second or two. On the second machine, it won't finish within > 30 minutes. Both are using geos as the postgis.backend. I don't understand > why the one is so much faster than the other with the identical data and > query. > > Any suggestions as to what to what the cause may be or how I might > diagnose the cause? > > Any clues would be greatly appreciated. > > TSW > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/postgis-users -- Darafei Praliaskouski Support me: http://patreon.com/komzpa
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