mysql - 尝试将数据库从 sqlite 更改为 mysql 时，rails 3 mysql2 gem 无法正常工作

Question

我已将 database.yml 更新为：

development:
    adapter: mysql2
    encoding: utf8
    reconnect: false
    database: dreamcity
    pool: 5
    username: root
    password: root
    host: localhost
    socket: /var/mysql/mysql.sock

我现在可以通过键入以下命令打开 mysql：rails dbconsole。但是当我尝试 rake db:schema:load 或 rake db:reset 时，rails 抱怨：

dyld: lazy symbol binding failed: Symbol not found: _mysql_init
  Referenced from: /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle
  Expected in: flat namespace

dyld: Symbol not found: _mysql_init
  Referenced from: /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle
  Expected in: flat namespace

有什么问题？我已将 mysql2 包含在 Gemfile 中并执行捆绑安装。其他一切都很好...