Building native extensions.  This could take a while...
ERROR:  Error installing pg:
        ERROR: Failed to build gem native extension.

/usr/bin/ruby1.9.1 extconf.rb
checking for pg_config... yes
Using config values from /usr/bin/pg_config
*** 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/bin/ruby1.9.1
        --with-pg
        --without-pg
        --with-pg-config
        --without-pg-config
        --with-pg_config
        --without-pg_config
        --with-pg-dir
        --without-pg-dir
        --with-pg-include
        --without-pg-include=${pg-dir}/include
        --with-pg-lib
        --without-pg-lib=${pg-dir}/lib
/usr/lib/ruby/1.9.1/mkmf.rb:368:in `try_do': The complier failed to generate an executable file. (RuntimeError)
You have to install development tools first.
        from /usr/lib/ruby/1.9.1/mkmf.rb:435:in `try_link0'
        from /usr/lib/ruby/1.9.1/mkmf.rb:440:in `try_link'
        from extconf.rb:39:in `<main>'


Gem files will remain installed in /var/lib/gems/1.9.1/gems/pg-0.17.0 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/pg-0.17.0/ext/gem_make.out