Postgresql Rails 3.1 推送到 Heroku 安装 postgres 适配器时出错

我刚刚升级到Rails 3.1，我try 部署到Heroku的第一个应用遇到了与Postgres adapter相关的问题.我可以将应用程序推送到heroku，但当我try 迁移数据库时，我会出现以下错误:

heroku rake db:迁移

rake aborted!
Please install the postgresql adapter: `gem install activerecord-postgresql-adapter` 
(pg is not part of the bundle. Add it to Gemfile.)
Tasks: TOP => db:migrate => db:load_config
(See full trace by running task with --trace)

当我try 他们建议的安装时，我得到:

ERROR:  Could not find a valid gem 'activerecord-postgresql-adapter' (>= 0) in any repository
ERROR:  Possible alternatives: activerecord-postgis-adapter, activerecord-jdbcpostgresql-adapter, activerecord-postgresql-cursors, activerecord-jdbcmysql-adapter, activerecord-jdbcmssql-adapter

这已经很奇怪了...那么，如果不是他们说我应该安装什么，我应该安装什么样的Ruby 才能让它工作呢？？

当我try 安装gem pg时，我得到:

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

/Users/jerometufte/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
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
    ...

我目前正在使用SQLite3.非常感谢您的帮助，这让我很困惑.