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I have found Gevel, a tool enabling the visualization of the content of the GiST indices in Postgres. In particular, I am interested to use it to visualize the RTree spatial index in PostGIS. Does it work with Postgres 2.0? Is there a simple way (not compiling from source) to get it to run (e.g., with postgis.app on Mac OSX?) Apparently, Gevel and the rtree-gist modules should now be part of the default Postgres distro as per the readme, but I cannot find any way to enable these.

EDIT: Following on from comments, if I have to build from source, do I have to build while building Postgis, or can I add gevel later.

  • I have recently installed Postgres 9.5 beta and neither rtree_gist nor gevel are in the postgresql-9.5beta2/contrib directory. I think the readme is a bit confusing on this. Having said that, I pulled from git and installed from source in a few minutes (on Centos 6.7, for what it is worth) and all the tests passed. I will post my steps, if you are interested -- basically, their instructions, with a few more details. In my experience, building from source on Mac is reasonably similar to linux, although setting up build essentials and the like is a bit more painful. – John Powell Feb 16 '16 at 7:21
  • It is gevel not gavel -- this confused me until coffee number two :-) Good find, though, it is an interesting package. – John Powell Feb 16 '16 at 7:23
  • Hi John, apologies for the confusion. Yes, please include your steps in the answers in the answers question, I would give it a try. Did you have to build the contrib packages WITH the postgis, or is this something that can be added retrospectively in a separate build (that would be my main question). – MartinT Feb 19 '16 at 3:22
  • I am still keen to resolve this question... – MartinT Mar 9 '16 at 22:53
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To answer your main question, you can build this after you have build Postgres/Postgis. However, the crucial part is that you need to do all of this from the

The crucial step in building from source is that the process relies on a file, contrib-global.mk, which is found in the Postgres contrib package. This is what is meant by step one in the instructions, namely,

cd PGSQLSRC/contrib
wget http://www.sai.msu.su/~megera/postgres/gist/gevel/gevel-8.0.x.tar.gz
make
make install
make installcheck

So, having the Postgres source files and running everything from the contrib subdirectory is the key step. I used updatedb and locate contrib-global-mk to find its location. This file in turn links to other make files in the Postgres bin directory. Unfortunately, this process requires pulling the Postgres source and building it, which I suspect you want to avoid. In practice, it is a very easy build and does not require the fiddling with pre-requisites, gdal, geos, proj4, etc, that Postgis does. It is possible to use the config switch prefix to set a path to the build, so as not to interfere with any existing Postgres installation, eg,

./configure --prefix=/usr/local/pgsql-9.5-test/

after which building gevel should be trivial.

  • @Martin, I have documented what I did, but I fear it will not be to your liking. I am not an expert by any means on build tools, but have generally found Postgres very easy to build (Postgis somewhat less so -- though usually due to older version of geos or gdal interfering). I got to the above through trial and error rather than a deep understanding of the process, but it was actually quite painless, once I realized I need to do everything relative to Postgres src/contrib. – John Powell Mar 10 '16 at 14:12
  • Thank you so much John - great answer that should get me some way. I am unclear about the parrt about ./configure . Is this an environment wide swithc you issued before the build, or is it in the make file? I am also unsure about updatedb and contrib-global-mk. Otherwise, thanks heaps! – MartinT Mar 15 '16 at 23:00
  • My understanding is that configure --prefix writes the makefile, and the value of prefix overrides anything else, so I suppose you can think of it as a pre-build environment wide switch. Apologies, updatedb is a linux utility for finding files and has nothing to do with Postgres, just a quick way to find out where my contrib-global.mk was installed. – John Powell Mar 17 '16 at 7:48

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