Error installing pg through capistrano deployment

Error installing pg through capistrano deployment

I have rails 2.3.8 app I have pg in my gemfile but showing error after
deployment
servers: ["apphost"]
[apphost] executing command
** [out :: apphost] Gem::Installer::ExtensionBuildError: ERROR: Failed to
build gem native extension.
** [out :: apphost]
** [out :: apphost] /usr/local/bin/ruby extconf.rb
** [out :: apphost] checking for pg_config... no
** [out :: apphost] No pg_config... trying anyway. If building fails,
please try again with
** [out :: apphost] --with-pg-config=/path/to/pg_config
** [out :: apphost] checking for libpq-fe.h... no
** [out :: apphost] Can't find the 'libpq-fe.h header
** [out :: apphost] *** extconf.rb failed ***
** [out :: apphost] Could not create Makefile due to some reason,
probably lack of
** [out :: apphost] necessary libraries and/or headers. Check the
mkmf.log file for more
** [out :: apphost] details. You may need configuration options.
** [out :: apphost]
** [out :: apphost] Provided configuration options: