Can't run the command -- rake:install - ruby-on-rails

Question

When I run the command rake:install, I get this error message:
WARNING: 'require 'rake/rdoctask'' is deprecated. Please use 'require 'rdoc/task' (in RDoc 2.4.2+)' instead.
at /Users/adam/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2.2/lib/rake/rdoctask.rb
Successfully built RubyGem
Name: mysql2psql
Version: 0.1.0
File: mysql2psql-0.1.0.gem
Executing "ruby -S gem install ./pkg/mysql2psql-0.1.0.gem":
ruby -S gem install ./pkg/mysql2psql-0.1.0.gem
Building native extensions. This could take a while...
ERROR: Error installing ./pkg/mysql2psql-0.1.0.gem:
ERROR: Failed to build gem native extension.
/Users/adam/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb
checking for pg_config... no
=========== WARNING ===========
You are building this extension on OS X without setting the
ARCHFLAGS environment variable, and pg_config wasn't found in
your PATH. If you are seeing this message, that means that the
build will probably fail.
If it does, you can correct this by either including the path
to 'pg_config' in your PATH or setting the environment variable
ARCHFLAGS to '-arch <arch>' before building.
For example:
(in bash) $ export PATH=/opt/local/lib/postgresql84/bin:$PATH
$ export ARCHFLAGS='-arch x86_64'
(in tcsh) % set path = ( /opt/local/lib/postgresql84/bin $PATH )
% setenv ARCHFLAGS '-arch x86_64'
Then try building again.
===================================
MacOS X build: fixing architecture flags:
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/radek/.rvm/rubies/ruby-1.9.2-p290/bin/ruby
--with-pg
--without-pg
--with-pg-config
--without-pg-config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
--enable-static-build
--disable-static-build
Gem files will remain installed in /Users/adam/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.9.0 for inspection.
Results logged to /Users/adam/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.9.0/ext/gem_make.out
rake aborted!
Command failed with status (1): [ruby -S gem install ./pkg/mysql2psql-0.1.0...]
Tasks: TOP => install
(See full trace by running task with --trace)
Apparently is the problem in the pg gem, but when I check the list of installed gems in my application, so there is * pg (0.13.2)
So what I am missing yet?

Answer 1

Solution for the issue above:
1. export PATH=/Library/PostgreSQL/9.1/bin:$PATH
2. export ARCHFLAGS='-arch x86_64'
3. rake install