[postgis-users] ST_ConcaveHull performance issue

Darafei "Komяpa" Praliaskouski me at komzpa.net
Thu Aug 1 22:54:39 PDT 2019


There were changes ST_ConcaveHull that fixed robustness of it in 2.2 -> 2.5
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.

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.web at 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.
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/postgis-users

Darafei Praliaskouski
Support me: http://patreon.com/komzpa
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20190802/ff105ec8/attachment.html>

More information about the postgis-users mailing list