進行主從配置的原因：
Master（主數據庫）負責寫操作的負載，也就是說一切寫的操作都在Master上進行，而讀的操作則分攤到Slave（從數據庫）上進行。這樣一來的可以大大提高讀取的效率。在一般的互聯網應用中，經過一些數據調查得出結論，讀/寫的比例大概在 10：1左右 ，也就是說大量的數據操作是集中在讀的操作，這也就是為什么我們會有多個Slave的原因。但是為什么要分離讀和寫呢？熟悉DB的研發人員都知道，寫操作涉及到鎖的問題，不管是行鎖還是表鎖還是塊鎖，都是比較降低系統執行效率的事情。我們這樣的分離是把寫操作集中在一個節點上，而讀操作其其他的N個節點上進行，從另一個方面有效的提高了讀的效率，保證了系統的高可用性。
$config = array();
//主庫配置
$config['db']['master']['host'] = 'localhost';
$config['db']['master']['username'] = 'root';
$config['db']['master']['password'] = 'root';
$config['db']['master']['port'] = '3306';
$config['db']['master']['database'] = 'weiqing';
$config['db']['master']['charset'] = 'utf8';
$config['db']['master']['pconnect'] = 0;
$config['db']['master']['tablepre'] = 'ims_';
//從庫配置 主從庫配置應當一致
$config['db']['slave_status'] = false; //是否開啟主從配置
$config['db']['slave']['1']['host'] = '';
$config['db']['slave']['1']['username'] = '';
$config['db']['slave']['1']['password'] = '';
$config['db']['slave']['1']['port'] = '3307';
$config['db']['slave']['1']['database'] = '';
$config['db']['slave']['1']['charset'] = 'utf8';
$config['db']['slave']['1']['pconnect'] = 0;
$config['db']['slave']['1']['tablepre'] = 'ims_';
$config['db']['slave']['1']['weight'] = 0;
$config['db']['common']['slave_except_table'] = array('core_sessions');
// -------------------------- CONFIG COOKIE --------------------------- //
$config['cookie']['pre'] = 'c432_';
$config['cookie']['domain'] = '';
$config['cookie']['path'] = '/';
// -------------------------- CONFIG SETTING --------------------------- //
$config['setting']['charset'] = 'utf-8';
$config['setting']['cache'] = 'memcache';
$config['setting']['timezone'] = 'Asia/Shanghai';
$config['setting']['memory_limit'] = '256M';
$config['setting']['filemode'] = 0644;
$config['setting']['authkey'] = '4c2c9fd4';
$config['setting']['founder'] = '1';
$config['setting']['development'] = 1;
$config['setting']['referrer'] = 0;
$config['setting']['https'] = 0;
// -------------------------- CONFIG UPLOAD --------------------------- //
$config['upload']['image']['extentions'] = array('gif', 'jpg', 'jpeg', 'png');
$config['upload']['image']['limit'] = 5000;
$config['upload']['attachdir'] = 'attachment';
$config['upload']['audio']['extentions'] = array('mp3');
$config['upload']['audio']['limit'] = 5000;
// -------------------------- CONFIG MEMCACHE --------------------------- //
$config['setting']['memcache']['server'] = '127.0.0.1';
$config['setting']['memcache']['port'] = 11211;
$config['setting']['memcache']['pconnect'] = 1;
$config['setting']['memcache']['timeout'] = 30;
$config['setting']['memcache']['session'] = 1;
$config['setting']['memcache']['sql'] = 1;
// -------------------------- CONFIG PROXY --------------------------- //
$config['setting']['proxy']['host'] = '';
$config['setting']['proxy']['auth'] = '';
// 積分抵扣
$config['setting']['redis']['server'] = '';
$config['setting']['redis']['port'] = 6379;
$config['setting']['redis']['pconnect'] = 0;
$config['setting']['redis']['requirepass'] = '';
$config['setting']['redis']['timeout'] = 30;