Can't find the 'libpq-fe.h header when trying to install pg gem

Question

I am using the Ruby on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error:

Answer 1

In my case it was package postgresql-server-dev-8.4 (I am on Ubuntu 11.04 (Natty Narwhal), 64 bits).