PHP实现的Mysql读写分离

本代码是从uchome的代码修改的，是因为要解决uchome的效率而处理的。这个思维其实很久就有了，只是一直没有去做，相信也有人有同样的想法，如果有类似的，那真的希望提出相关的建议。

封装的方式比较简单，增加了只读数据库连接的接口扩展，不使用只读数据库也不影响原代码使用。有待以后不断完善。。

为了方便，试试建立了google的一个项目：
http://code.google.com/p/mysql-rw-php/

希望给有需要的朋友带来帮助。

PHP实现的Mysql读写分离

主要特性：

1. 简单的读写分离
2. 一个主数据库，可以添加更多的只读数据库
3. 读写分离但不用担心某些特性不支持
4. 缺点：同时连接两个数据库

英文比较烂，也写几个字吧

php code for mysql read/write split
feature:
simply rw split
one master,can add more slaves
support all mysql feature
link to the master and slave at the same time

PHP代码：

mysql_rw_php.class.php

<?php /**************************************** *** mysql-rw-php version 0.1 @ 2009-4-16 *** code by hqlulu#gmail.com *** http://www.aslibra.com *** http://code.google.com/p/mysql-rw-php/ *** code modify from class_mysql.php (uchome) ****************************************/ class mysql_rw_php {   //查询个数   var $querynum = 0;   //当前操作的数据库连接   var $link = null;   //字符集   var $charset;   //当前数据库   var $cur_db = '';   //是否存在有效的只读数据库连接   var $ro_exist = false;   //只读数据库连接   var $link_ro = null;   //读写数据库连接   var $link_rw = null;   function mysql_rw_php(){   }   function connect($dbhost, $dbuser, $dbpw, $dbname = '', $pconnect = 0, $halt = TRUE) {     if($pconnect) {       if(!$this->link = @mysql_pconnect($dbhost, $dbuser, $dbpw)) {         $halt && $this->halt('Can not connect to MySQL server');       }     } else {       if(!$this->link = @mysql_connect($dbhost, $dbuser, $dbpw)) {         $halt && $this->halt('Can not connect to MySQL server');       }     }         //只读连接失败     if(!$this->link && !$halt) return false;         //未初始化rw时，第一个连接作为rw     if($this->link_rw == null)       $this->link_rw = $this->link;     if($this->version() > '4.1') {       if($this->charset) {         @mysql_query("SET character_set_connection=$this->charset, character_set_results=$this->charset, character_set_client=binary", $this->link);       }       if($this->version() > '5.0.1') {         @mysql_query("SET sql_mode=''", $this->link);       }     }     if($dbname) {       $this->select_db($dbname);     }   }   //连接一个只读的mysql数据库   function connect_ro($dbhost, $dbuser, $dbpw, $dbname = '', $pconnect = 0){     if($this->link_rw == null)       $this->link_rw = $this->link;     $this->link = null;     //不产生halt错误     $this->connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect, false);     if($this->link){       //连接成功       //echo "link ro sussess!<br>";       $this->ro_exist = true;       $this->link_ro = $this->link;       if($this->cur_db){         //如果已经选择过数据库则需要操作一次         @mysql_select_db($this->cur_db, $this->link_ro);       }     }else{       //连接失败       //echo "link ro failed!<br>";       $this->link = &$this->link_rw;     }   }   //设置一系列只读数据库并且连接其中一个   function set_ro_list($ro_list){     if(is_array($ro_list)){       //随机选择其中一个       $link_ro = $ro_list[array_rand($ro_list)];       $this->connect_ro($link_ro['dbhost'], $link_ro['dbuser'], $link_ro['dbpw']);     }   }   function select_db($dbname) {     //同时操作两个数据库连接     $this->cur_db = $dbname;     if($this->ro_exist){       @mysql_select_db($dbname, $this->link_ro);     }     return @mysql_select_db($dbname, $this->link_rw);   }   function fetch_array($query, $result_type = MYSQL_ASSOC) {     return mysql_fetch_array($query, $result_type);   }   function fetch_one_array($sql, $type = '') {     $qr = $this->query($sql, $type);     return $this->fetch_array($qr);   }   function query($sql, $type = '') {     $this->link = &$this->link_rw;     //判断是否select语句     if($this->ro_exist && preg_match ("/^(\s*)select/i", $sql)){       $this->link = &$this->link_ro;     }     $func = $type == 'UNBUFFERED' && @function_exists('mysql_unbuffered_query') ?       'mysql_unbuffered_query' : 'mysql_query';     if(!($query = $func($sql, $this->link)) && $type != 'SILENT') {       $this->halt('MySQL Query Error', $sql);     }     $this->querynum++;     return $query;   }   function affected_rows() {     return mysql_affected_rows($this->link);   }   function error() {     return (($this->link) ? mysql_error($this->link) : mysql_error());   }   function errno() {     return intval(($this->link) ? mysql_errno($this->link) : mysql_errno());   }   function result($query, $row) {     $query = @mysql_result($query, $row);     return $query;   }   function num_rows($query) {     $query = mysql_num_rows($query);     return $query;   }   function num_fields($query) {     return mysql_num_fields($query);   }   function free_result($query) {     return mysql_free_result($query);   }   function insert_id() {     return ($id = mysql_insert_id($this->link)) >= 0 ? $id : $this->result($this->query("SELECT last_insert_id()"), 0);   }   function fetch_row($query) {     $query = mysql_fetch_row($query);     return $query;   }   function fetch_fields($query) {     return mysql_fetch_field($query);   }   function version() {     return mysql_get_server_info($this->link);   }   function close() {     return mysql_close($this->link);   }   function halt($message = '', $sql = '') {     $dberror = $this->error();     $dberrno = $this->errno();     echo "<div style=\"position:absolute;font-size:11px;font-family:verdana,arial;background:#EBEBEB;padding:0.5em;\">         <b>MySQL Error</b><br>         <b>Message</b>: $message<br>         <b>SQL</b>: $sql<br>         <b>Error</b>: $dberror<br>         <b>Errno.</b>: $dberrno<br>         </div>";     exit();   } } ?>

example.php

<?php /**************************************** *** mysql-rw-php version 0.1 @ 2009-4-16 *** code by hqlulu#gmail.com *** http://www.aslibra.com *** http://code.google.com/p/mysql-rw-php/ *** code modify from class_mysql.php (uchome) ****************************************/ require_once('mysql_rw_php.class.php'); //rw info $db_rw = array(   'dbhost'=>'www.aslibra.com',   'dbuser'=>'aslibra',   'dbpw'=>'www.aslibra.com',   'dbname'=>'test' ); $db_ro = array(   array(     'dbhost'=>'www.aslibra.com:4306',     'dbuser'=>'aslibra',     'dbpw'=>'www.aslibra.com'   ) ); $DB = new mysql_rw_php; //connect Master $DB->connect($db_rw[dbhost], $db_rw[dbuser], $db_rw[dbpw], $db_rw[dbname]); //Method 1: connect one server $DB->connect_ro($db_ro[0][dbhost], $db_ro[0][dbuser], $db_ro[0][dbpw]); //Method 2: connect one server from a list by rand $DB->set_ro_list($db_ro); //send to rw $sql = "insert into a set a='test'"; $DB->query($sql); //send to ro $sql = "select * from a"; $qr = $DB->query($sql); while($row = $DB->fetch_array($qr)){   echo $row[a]; } ?>