[R] RPostgreSQL: unable to load shared library

[Prof Brian Ripley]

On Wed, 14 Oct 2009, Fanfaar wrote:

> Hello list,
>
> I'm using R 2.9.2 on a WinXP system, and I installed the RPostgreSQL
> library using the package installer. When trying to load it, I get the
> following error:
>
>> library('RPostgreSQL')
> Error in inDL(x, as.logical(local), as.logical(now), ...) :
>  unable to load shared library
> 'C:/PROGRA~1/R/R/library/RPostgreSQL/libs/RPostgreSQL.dll':
>  LoadLibrary failure:  The operating system cannot run %1.
>
> Error: package/namespace load failed for 'RPostgreSQL'
>
> So one way or the other, the DLL is not found... Does anyone know how

That is not what it says: it says it cannot *load* the DLL.  You need 
the PostgreSQL client dll in your path, and I guess that (or its 
version) is the problem.  (Usually Windows gives you a popup with more 
information, and indeed on my laptop it told me LIBPQ.DLL could not be 
found.) And pedump suggests that it is linked against entry points by 
number not name, a very fragile arrangement.

I always worry that packages that link to external DLLs can be very 
dependent on the version of that DLL (and see the above comment).  I 
could not see a description of the version of PostgreSQL used on Uwe's 
ReadMe (assuming this is a binary from CRAN), and suggest (as did the 
rw-FAQ) that you install RPostgreSQL from source against your own 
PostgreSQL installation.  (That's what I do on my Windows desktop 
which does have PostgreSQL installed, and when I updated PostgreSQL I 
had to re-install PostgreSQL ....)

> to fix this? I don't suppose DLL should be directly in my PATH, right?
>
> Thanks for any hints,
> Arnout
>
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Yes another person who thinks that does not apply to them.


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595