Detailed explanation of read and write separation of MySQL database under thinkphp

This article mainly introduces the analysis of the read-write separation code of the MySQL database under thinkphp. It has certain reference value. Interested friends can refer to it.

When using the original SQL statement for write operations, execute is used, and query is used for read operations.

MySQL data master-slave synchronization still relies on the MySQL mechanism, so the delay problem of MySQL master-slave synchronization needs to be optimized at this time. If the delay time is too long, it not only affects the business, but also affects the user experience.

In the thinkphp core class Thinkphp/library/Model.class.php, the query method calls Thinkphp/library/Think/Db/Driver/Mysql.class.php

  /**
   * SQL查询
   * @access public
   * @param string $sql SQL
   * @param mixed $parse 是否需要解析SQL 
   * @return mixed
   */
  public function query($sql,$parse=false) {
    if(!is_bool($parse) && !is_array($parse)) {
      $parse = func_get_args();
      array_shift($parse);
    }
    $sql =  $this->parseSql($sql,$parse);
    return $this->db->query($sql);
  }

Call Thinkphp/library/Think/Db/Driver/Mysql.class.php

  /**
   * 执行查询 返回数据集
   * @access public
   * @param string $str sql指令
   * @return mixed
   */
  public function query($str) {
    if(0===stripos($str, 'call')){ // 存储过程查询支持
      $this->close();
      $this->connected  =  false;
    }
    $this->initConnect(false);
    if ( !$this->_linkID ) return false;
    $this->queryStr = $str;
    //释放前次的查询结果
    if ( $this->queryID ) {  $this->free();  }
    N('db_query',1);
    // 记录开始执行时间
    G('queryStartTime');
    $this->queryID = mysql_query($str, $this->_linkID);
    $this->debug();
    if ( false === $this->queryID ) {
      $this->error();
      return false;
    } else {
      $this->numRows = mysql_num_rows($this->queryID);
      return $this->getAll();
    }
  }

When initializing the database link above, initConnect(false) calls Thinkphp/library/Think/Db/Db.class.php, pay attention to the false and true code implementation. true means calling the main library directly, false means calling the reading library with separate reading and writing.

  /**
   * 初始化数据库连接
   * @access protected
   * @param boolean $master 主服务器
   * @return void
   */
  protected function initConnect($master=true) {
    if(1 == C('DB_DEPLOY_TYPE'))
      // 采用分布式数据库
      $this->_linkID = $this->multiConnect($master);
    else
      // 默认单数据库
      if ( !$this->connected ) $this->_linkID = $this->connect();
  }

  /**
   * 连接分布式服务器
   * @access protected
   * @param boolean $master 主服务器
   * @return void
   */
  protected function multiConnect($master=false) {
    foreach ($this->config as $key=>$val){
      $_config[$key]   =  explode(',',$val);
    }    
    // 数据库读写是否分离
    if(C('DB_RW_SEPARATE')){
      // 主从式采用读写分离
      if($master)
        // 主服务器写入
        $r =  floor(mt_rand(0,C('DB_MASTER_NUM')-1));
      else{
        if(is_numeric(C('DB_SLAVE_NO'))) {// 指定服务器读
          $r = C('DB_SLAVE_NO');
        }else{
          // 读操作连接从服务器
          $r = floor(mt_rand(C('DB_MASTER_NUM'),count($_config['hostname'])-1));  // 每次随机连接的数据库
        }
      }
    }else{
      // 读写操作不区分服务器
      $r = floor(mt_rand(0,count($_config['hostname'])-1));  // 每次随机连接的数据库
    }
    $db_config = array(
      'username' => isset($_config['username'][$r])?$_config['username'][$r]:$_config['username'][0],
      'password' => isset($_config['password'][$r])?$_config['password'][$r]:$_config['password'][0],
      'hostname' => isset($_config['hostname'][$r])?$_config['hostname'][$r]:$_config['hostname'][0],
      'hostport' => isset($_config['hostport'][$r])?$_config['hostport'][$r]:$_config['hostport'][0],
      'database' => isset($_config['database'][$r])?$_config['database'][$r]:$_config['database'][0],
      'dsn'    => isset($_config['dsn'][$r])?$_config['dsn'][$r]:$_config['dsn'][0],
      'params'  => isset($_config['params'][$r])?$_config['params'][$r]:$_config['params'][0],
      'charset'  => isset($_config['charset'][$r])?$_config['charset'][$r]:$_config['charset'][0],      
    );
    return $this->connect($db_config,$r);
  }

query method parameter is false, other delete, update, add read main library. This can be combined with the delete, save, and add operations in Thinkphp/library/Model.class.php, and the parameter is true.

The above is the entire content of this article, I hope it will be helpful to everyone's study.

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