Hi, sorry for the delay in replying. You were right -- it was not finding the correct version of the library. In fact, all I had to do was change the order in my LD_LIBRARY_PATH -- but thanks for the suggestion on strace -- I will certainly be using this tool for future problems. Many thanks Martin John Goerzen wrote:

On 2006-07-10, Martin Percossi wrote:

...

Hi, I'm having problems using HDBC-postgresql (I've tried both 0.99.2.1 and 1.0.0.0) with postgresql (version 8.1.4, installed in /share/pgsql). I adjust the include-dir and extra-lib-dirs to use the custom location of postgresql, and build: no error messages, everything seems fine.

Probably, though, there is something that is not quite fine...

...

However, when I then try to type: ghci -package HDBC -package HDBC-postgresql , I get the error message: Loading package HDBC-postgresql-0.99.2.1 ... linking ... ghc-6.4.2: /home/mpercossi/opt/lib/HDBC-postgresql-0.99.2.1/HSHDBC-postgresql-0.99.2.1.o: unknown symbol `PQserverVersion' ghc-6.4.2: unable to load package `HDBC-postgresql-0.99.2.1'

This sounds like it's not finding your PostgreSQL libraries.

First, can you confirm that PQserverVersion still occurs in your libpq-fe.h?

Next, try strace on your ghci session.

Grep for libpq in the output. It may be instructive.

In my case, I saw:

stat64("/usr/lib/haskell-packages/ghc6/lib/HDBC-postgresql-0.99.2.1/libpq_dyn.so", 0xb763a1e0) = -1 ENOENT (No such file or directory) stat64("/usr/lib/haskell-packages/ghc6/lib/HDBC-postgresql-0.99.2.1/libpq.so", 0xb763a570) = -1 ENOENT (No such file or directory) open("/usr/lib/libpq.so", O_RDONLY) = 3

So we know that the system did successfully open that library.

...

Has anyone seen this error message before? Google didn't turn up anything relevant to haskell -- however there does seem to be a PQserverVersion procedure in the libpq library -- maybe HDBC-postgresql is not seeing this due to the custom install location?

This would all be up to your modifications to cabal.

Try: ghc-pkg describe HDBC-postgresql

You should see:

* pq in the extra-libraries line * Your header file location in the include-dirs line * Your extra-lib-dirs path

If you don't see those things, then something went wrong with the build or install.

I would also suggesting building a program with GHC (not GHCI) that uses HDBC-postgresql for testing.

-- John

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