[postgis-users] ST_ConcaveHull performance issue

[Trevor Wiens]

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
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