[postgis-users] Error installing PostGIS on agensdb

Regina Obe lr at pcorp.us
Fri May 3 13:48:52 PDT 2019

That error is a generic error.  Not terribly helpful error unfortunately. 


It gives that whenever the file can't be loaded by PostgreSQL daemon because


1)      It's missing a dependent library (which is where dependency walker is handy to pick out) – this is the most common case.  In EDB PostgreSQL the extension libs try to find the dependency libraries in the bin folder, but in BigSQL it's pg<whateverversion>/postgresql/bin So if you copied the dependency files to the wrong folder, you would get this error.

2)      The floatbyvalue compilation is wrong

3)      The bitness is wrong – e.g. you have PostgreSQL 32-bit and trying to load a 64-bit dll

4)      You do have right named dll version in right place but wrong version of the library – such as the case if say you compiled PostGIS against GEOS 3.7, but you are trying to use a GEOS 3.6 library (this one is trickier to troubleshoot).

If you don't have files in the right place in PostgreSQL folder, it may resort to finding stuff in system32 which may be completely incompatible.


As I recall I think if you compiled against a different PostgreSQL version e.g. trying to load say a 11 lib in a 9.6 PostgreSQL it does give a more meaningful version mismatch error.

It might also give a more meaningful message trying to use 64-bit lib in a 32-bit PostgreSQL, but it's been a while since I've seen that so not sure.




From: postgis-users [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of David Haynes
Sent: Friday, May 03, 2019 12:23 PM
To: PostGIS Users Discussion <postgis-users at lists.osgeo.org>
Subject: Re: [postgis-users] Error installing PostGIS on agensdb


Can you elaborate a bit more on why "the dll can not be loaded"


I'm confused as the error asks for a file at a specific location and the file is there at that exact location.


On Wed, May 1, 2019 at 12:55 PM Regina Obe <lr at pcorp.us <mailto:lr at pcorp.us> > wrote:

Not familiar with how AgensDB puts things.

That error happens whenever the dll can't be loaded.


You might be better off using the binaries instead of the installer as I think the paths you put things relative to PostgreSQL install folder may be different.


For example in BigSQL things go  in


the lib files go into lib/postgresql folder, share/extension files in share/postgresql  and bin in bin


So that's why the installer can never work for BigSQL and you have to use the binaries.


The other issue is I don't ship files in the zip or installer that I know EDB ships to prevent accidental overwriting.

So you maybe need to copy those separately from elsewhere. 


If you use Dependency Walker (x64 version) - http://www.dependencywalker.com/  will tell you the dependencies you need or are missing.


There is yet another reason why this error happens, and that depends compile switches (--disable-float8-byval) comes to mind

For example EDB PostgreSQL used to have this off pre-9.5 so I had (--disable-float8-byval  ) when compiling and so the pre-9.5 binaries I built weren't compatible with BigSQL  because I had to use this switch too.


Post 9.5 both EDB and BigSQL don't use this switch so the binaries are compatible.  So if agent is doing something else, you probably can't use these binaries at all and will have to compile your own or pay someone to do so (like me :) ).


BTW just uploaded the 2.5.2 zip and binaries for 10. 


Hope that helps,




From: postgis-users [mailto:postgis-users-bounces at lists.osgeo.org <mailto:postgis-users-bounces at lists.osgeo.org> ] On Behalf Of David Haynes
Sent: Wednesday, May 01, 2019 12:15 PM
To: postgis-users at lists.osgeo.org <mailto:postgis-users at lists.osgeo.org> 
Subject: [postgis-users] Error installing PostGIS on agensdb




I'm running into an error trying to enable the postgis extension on AgensDB (a fork of PostgreSQL). My setup is on a windows machine, PSQL 10.4. I have done this sucessfully once before, but I am unable to replicate it on my new machine.


The process I used is the following. I downloaded the precompiled windows binaries (postgis-bundle-pg10x64-setup-2.5.1-1.exe) and executed it within the agens directory successfully, but it still errors. The error below is strange because the file exists within the directory.


agens -p 5433 -U agens -c "CREATE EXTENSION postgis"

ERROR:  could not load library "C:/AgensGraph-2.1.0/lib/rtpostgis-2.5.dll": The specified module could not be found.

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