'db' =>[ 
   'class' => 'yii\db\Connection', 
 
  // 配置主服务器 
  'dsn' => 'dsn for master server', 
  'username' => 'master', 
  'password' => '', 
  'charset' => 'utf8', 
  'tablePrefix' => 'php_',//默认为空 
 
  // 配置从服务器 
  'slaveConfig' => [ 
    'username' => 'slave', 
    'password' => '', 
    'charset' => 'utf8', 
   'tablePrefix' => 'php_', 
    'attributes' => [ 
      // use a smaller connection timeout 
      PDO::ATTR_TIMEOUT => 10, 
    ], 
   
  ], 
]; 

'db'=>[ 
  //...上面是一些标准配置 
  'slaves' => [ 
    ['dsn' => 'dsn for slave server 1'], 
    ['dsn' => 'dsn for slave server 2'], 
    ['dsn' => 'dsn for slave server 3'], 
    ['dsn' => 'dsn for slave server 4'], 
  ],  
] 

'db'=>[ 
  // 配置主服务器 
  'masterConfig' => [ 
    'username' => 'master', 
    'password' => '', 
    'attributes' => [ 
      // use a smaller connection timeout 
      PDO::ATTR_TIMEOUT => 10, 
    ], 
  ], 
 
  // 配置主服务器组 
  'masters' => [ 
    ['dsn' => 'dsn for master server 1'], 
    ['dsn' => 'dsn for master server 2'], 
  ], 
  //other ...slaves 
];