php+MySQL Proxy快速实现读写分离以及负载均衡，故障转移

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MySQL PHP Lua SQL Server SQL

简单的说，MySQL Proxy就是一个连接池，负责将前台应用的连接请求转发给后台的数据库，并且通过使用lua脚本 ，可以实现复杂的连接控制和过滤，从而实现读写分离和负载平衡。对于应用来说，MySQL Proxy是完全透明的，应用则只需要连接到MySQL Proxy的监听端口即可。当然，这样proxy机器可能成为单点失效，但完全可以使用多个proxy机器做为冗余，在应用服务器的连接池配置中配置到多个proxy的连接参数即可。

典型配置案例:
1、最基础的应用，代理单个数据库服务器，这样就可以通过4040端口访问mysql数据库。
mysql-proxy –proxy-backend-addresses=192.168.18.110:3306
2、连接多个数据库服务器，假如A and B. 第一个客户端连接到 A,第二个连接到 B。
如果有一台停止服务时，代理会自动检测到，有新连接时会自动连接到一台正常的数据库。
mysql-proxy \
–proxy-backend-addresses=narcissus:3306 \
–proxy-backend-addresses=nostromo:3306
3、数据库读写分离，192.168.18.110负责写入，192.168.18.107负责读取数据，当然也可以再增加读取数据的服务器。
mysql-proxy \
–proxy-backend-addresses=192.168.18.110:3306 \
–proxy-read-only-backend-addresses=192.168.18.107:3306
这种方式常被理解为可以读写分离了，但是实际不是的。mysql-proxy不能区分哪些是发往从服务器的，还需要自己用脚本控制，见第四种方式。
4、 Lua 脚本能很好的控制连接和分布, 以及查询及返回的结果集.
使用Lua脚本时，必须使用 –proxy-lua-script 指定脚本的名称。
直到产生连接的时候才会读取脚本，也就是修改脚本后不用重新启动服务。
mysql-proxy –proxy-lua-script=rw-splitting.lua –proxy-backend-addresses=192.168.18.110:3306 –proxy-read-only-backend-addresses=192.168.18.107:3306
注意的问题：
1、proxy的读写分离机制是先把最初的几条查询发到master上建立连接，
当发送到master上的查询数超过连接池的最小值时开始把查询
2、LAST_INSERT_ID不能发送到主服务器上， 226 行修改为下面的就可以了
elseif not is_insert_id and token.token_name == “TK_FUNCTION” then
3、使用默认的rw-splitting.lua时，会提示找不到proxy-command，我把mysql-proxy的路径设置为系统路径，然后在 share目录下运行就一切Ok了，在运行中输入cmd，然后cd C:\tools\mysql-proxy\share。
4、字符乱码
通过proxy连上数据库之后，查到的字符串始终是乱码，即便手工执行了set names ‘utf8′也没有效果。
解决办法，mysql server必须设置
1.[mysqld]
2.skip-character-set-client-handshake
3. init-connect=’SET NAMES utf8′
4. default-character-set=utf8

public function isReadOperation($sql) {
     return preg_match('/^\s*(SELECT|SHOW|DESC|PRAGMA)\s+/i',$sql);
}

public function isReadOperation($sql) {
	return preg_match('/^\s*(SELECT|SHOW|DESC|PRAGMA)\s+/i',$sql);
}

php读写分离类

 /****************************************
*** 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!";
             $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!";
             $this->link = &$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 ">
                MySQL Error
                 Message: $message
                 SQL: $sql
                 Error: $dberror
                 Errno.: $dberrno

";   

        exit();   

    }   

}   

  

?>  

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!
";
			$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!
";
			$this->link = &$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 "

				MySQL Error

				Message: $message

				SQL: $sql

				Error: $dberror

				Errno.: $dberrno

				
";
		exit();
	}
}

?>

 调用方法

 /****************************************
*** 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];
}
?>

'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];
}
?>