Thanks to both of you. I tried running with perf now and found most of the time was spent in libstdc++ doing dynamic casting and related functions for 80% of CPU time. Within geos itself, the top time spent is in the SimplePoitnInAreaLocator and STRIntersectsOp functions.
I don't know how geos works well enough to say of this is a related issue. TSW On Fri, Aug 2, 2019 at 11:40 AM Regina Obe <[email protected]> wrote: > There is was an issue with ST_Union as applied to invalid polygons > introduced in 3.7.1 and 3.6.2 which would make ST_Union run indefinitely. > It appears to still be an open bug. This smells like that issue. > > > > https://trac.osgeo.org/geos/ticket/867 > > > > https://lists.osgeo.org/pipermail/postgis-users/2018-April/042710.html > > > > > > > > *From:* postgis-users [mailto:[email protected]] *On > Behalf Of *Trevor Wiens > *Sent:* Friday, August 2, 2019 1:16 PM > *To:* PostGIS Users Discussion <[email protected]> > *Subject:* Re: [postgis-users] ST_ConcaveHull performance issue > > > > Thanks for your reply. It was mix of points, lines and polygons, but when > I broke it down it was the lines causing the problem. > > > > I tried commenting out the line in the ST_ConcaveHull function you > suggested but that doesn't make a difference. I suspect there is some > underlying library that has changed. > > > > I will open a ticket as you suggest. > > > > Thanks > > > > TSW > > > > On Thu, Aug 1, 2019 at 11:55 PM Darafei "Komяpa" Praliaskouski < > [email protected]> wrote: > > 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 <[email protected]> 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 > [email protected] > https://lists.osgeo.org/mailman/listinfo/postgis-users > > > > > -- > > Darafei Praliaskouski > > Support me: http://patreon.com/komzpa > > _______________________________________________ > postgis-users mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/postgis-users > > > > -- > > Trevor Wiens > Apropos Information Systems > aproposinfosystems.com > Calgary, Alberta > > Ph. 403-973-5901 > _______________________________________________ > postgis-users mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/postgis-users -- Trevor Wiens Apropos Information Systems aproposinfosystems.com Calgary, Alberta Ph. 403-973-5901
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