Good day!
I have problems installing postgres gem.
It seems that gem cannot find my PostgreSQL installation.
Please tell me what options can I give to gem. Gem manual doesn't help.

I'm getting the following:

ERROR:  While executing gem ... (Gem::Installer::ExtensionBuildError)
     ERROR: Failed to build gem native extension.

ruby extconf.rb install postgres
checking for cygwin32_socket() in -lwsock32... no
checking for socket() in -lsocket... no
checking for gethostbyname() in -linet... no
checking for gethostbyname() in -lnsl... no
checking for sys/un.h... yes
checking for socket()... yes
checking for hsterror()... no
checking for gethostname()... yes
checking for PQsetdbLogin() in -lpq... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
         --with-opt-dir
         --without-opt-dir
         --with-opt-include
         --without-opt-include=${opt-dir}/include
         --with-opt-lib
         --without-opt-lib=${opt-dir}/lib
         --with-make-prog
         --without-make-prog
         --srcdir=.
         --curdir
         --ruby=/usr/local/bin/ruby
         --with-pgsql-dir
         --without-pgsql-dir
         --with-pgsql-include
         --without-pgsql-include=${pgsql-dir}/include
         --with-pgsql-lib
         --without-pgsql-lib=${pgsql-dir}/lib
         --with-wsock32lib
         --without-wsock32lib
         --with-socketlib
         --without-socketlib
         --with-inetlib
         --without-inetlib
         --with-nsllib
         --without-nsllib
         --with-pgsql-include-dir
         --without-pgsql-include-dir
         --with-pgsql-lib-dir
         --without-pgsql-lib-dir
         --with-pqlib
         --without-pqlib
Could not find PostgreSQL libraries: Makefile not created


Gem files will remain installed in 
/usr/local/lib/ruby/gems/1.8/gems/postgres-0.7.1 for inspection.
Results logged to 
/usr/local/lib/ruby/gems/1.8/gems/postgres-0.7.1/gem_make.out

Yours sincerely,
Damian/Three-eyed Fish