“cannot find -lpq” when trying to install psycopg2

Question

Intro : I'm trying to migrate our Trac SQLite to a PostgreSQL backend, to do that I need psycopg2. After clicking past the embarrassing rant on www.initd.org I downloaded the latest version and tried running setup.py install . This didn't work, telling me I needed mingw. So I downloaded and installed mingw.

Problem : I now get the following error when running setup.py build_ext --compiler=mingw32 install :

running build_ext
building 'psycopg2._psycopg' extension
writing build\temp.win32-2.4\Release\psycopg\_psycopg.def
C:\mingw\bin\gcc.exe -mno-cygwin -shared -s build\temp.win32-2.4\Release\psycopg
\psycopgmodule.o build\temp.win32-2.4\Release\psycopg\pqpath.o build\temp.win32-
2.4\Release\psycopg\typecast.o build\temp.win32-2.4\Release\psycopg\microprotoco
ls.o build\temp.win32-2.4\Release\psycopg\microprotocols_proto.o build\temp.win3
2-2.4\Release\psycopg\connection_type.o build\temp.win32-2.4\Release\psycopg\con
nection_int.o build\temp.win32-2.4\Release\psycopg\cursor_type.o build\temp.win3
2-2.4\Release\psycopg\cursor_int.o build\temp.win32-2.4\Release\psycopg\lobject_
type.o build\temp.win32-2.4\Release\psycopg\lobject_int.o build\temp.win32-2.4\R
elease\psycopg\adapter_qstring.o build\temp.win32-2.4\Release\psycopg\adapter_pb
oolean.o build\temp.win32-2.4\Release\psycopg\adapter_binary.o build\temp.win32-
2.4\Release\psycopg\adapter_asis.o build\temp.win32-2.4\Release\psycopg\adapter_
list.o build\temp.win32-2.4\Release\psycopg\adapter_datetime.o build\temp.win32-
2.4\Release\psycopg\_psycopg.def -LC:\Python24\libs -LC:\Python24\PCBuild -Lc:/P
ROGRA~1/POSTGR~1/8.3/lib -lpython24 -lmsvcr71 -lpq -lmsvcr71 -lws2_32 -ladvapi32
 -o build\lib.win32-2.4\psycopg2\_psycopg.pyd
C:\mingw\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\mingw32\bin\ld.exe: cannot fin
d -lpq
collect2: ld returned 1 exit status
error: command 'gcc' failed with exit status 1

What I've tried - I noticed the forward slashes in the -L option, so I manually entered my PostgreSQL lib directory in the library_dirs option in the setup.cfg, to no avail (the call then had a -L option with backslashes, but the error message stayed the same).

Answer 1

Have you tried the binary build of psycopg2 for windows? If that works with your python then it mitigates the need to build by hand.

I've seen random people ask this question on various lists and it seems one recommendation is to build postgresql by hand to work around this problem.

Answer 2

Compiling extensions on windows can be tricky. There are precompiled libraries available however: http://www.stickpeople.com/projects/python/win-psycopg/