PHP method to implement database sharding failure recovery

With the rapid development of the Internet, more and more companies are migrating business systems to the cloud and using distributed architecture to handle huge amounts of data and high concurrent traffic. However, in a distributed architecture, fault recovery becomes more complex. Especially when a sharded database failure occurs, the data on the failed node needs to be restored in time, otherwise the stable operation of the business may be seriously affected. This article will introduce how to use PHP to achieve database sharding failure recovery.

1. The impact of sharded database failure

Sharding is to divide a piece of data into multiple subsets and store them in different database servers to achieve distributed storage and load balancing the goal of. However, when a certain shard fails, it will affect the operation of the entire business.

Suppose an e-commerce platform has a user order table placed on sharded database A, and sharded database A suddenly fails. At this time, the entire merchant order query and payment process will be hindered, and users cannot function normally. Completed ordering and payment for the product. Therefore, in a sharded database architecture, failure recovery becomes particularly important.

2. PHP process for realizing database sharding failure recovery

In order to solve the problem of sharded database failure, we can use master-slave replication and HA solution to achieve failover and data recovery. The following is the process for PHP to implement database sharding failure recovery:

1. Master-slave database replication

Master-slave replication replicates data through the MySQL binary log. The master database writes data and Write it into a binary log file, and the slave database copies the binary log file to its own server to ensure that the data in the slave database is consistent with the master database. In this way, after the main database fails, the slave database can be quickly switched to the main database to ensure the stable operation of the business system.

2.HA solution

The HA (High Availability) solution can automatically switch failed nodes to ensure the stability of the business system. The HA solution uses VRRP (Virtual Router Redundancy Protocol) or other protocols to implement virtual IP address switching.

When a node is found to be faulty, the HA system will automatically point the IP address to its backup node. At this time, the standby node will automatically become the master node and start the replication service to ensure data consistency and high reliability.

3. Automatic switching program

The automatic switching program is used to monitor the master database and the slave database. When the master database fails, it will automatically switch from the slave database to the master database. The automatic switching program can automatically switch without manual intervention, so that the business system can continue to operate stably.

4. Data recovery procedure

Once a sharded database failure occurs, failure recovery needs to be carried out quickly to restore the data from the standby node. The data recovery program can export the data from the standby node to the failed node through MySQL's mysqldump command to achieve rapid data recovery.

3. PHP code implementation for database sharding fault recovery

This article uses PHP language as an example to demonstrate the code implementation for database sharding fault recovery.

1. Configure the virtual IP address of the database master-slave server and HA solution:

$master_db_host = '192.168.1.1';
$master_db_user = 'root';
$master_db_pwd = '123456';
$master_db_name = 'orders';

$slave_db_host = '192.168.1.2';
$slave_db_user = 'root';
$slave_db_pwd = '123456';
$slave_db_name = 'orders';

$vip = '192.168.1.3';

2. Implement the master-slave replication function, set the master server and slave server in the database, and implement database replication. ：

$dsn = "mysql:host=$master_db_host;dbname=$master_db_name";
$user = $master_db_user;
$pwd = $master_db_pwd;

try {
    $pdo = new PDO($dsn, $user, $pwd);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->exec('SET NAMES utf8');
    $stmt = $pdo->query("SHOW MASTER STATUS");
    $master_status = $stmt->fetch(PDO::FETCH_ASSOC);
    $pdo = null;
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

$dsn = "mysql:host=$slave_db_host;dbname=$slave_db_name";

try {
    $pdo = new PDO($dsn, $slave_db_user, $slave_db_pwd);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->exec('SET NAMES utf8');
    $stmt = $pdo->prepare("STOP SLAVE;");
    $stmt->execute();

    $stmt = $pdo->prepare("CHANGE MASTER TO MASTER_HOST=:host, "
            . "MASTER_USER=:user, MASTER_PASSWORD=:pwd, "
            . "MASTER_LOG_FILE=:log_file, MASTER_LOG_POS=:log_pos;");
    $stmt->bindParam(":host", $master_db_host, PDO::PARAM_STR);
    $stmt->bindParam(":user", $master_db_user, PDO::PARAM_STR);
    $stmt->bindParam(":pwd", $master_db_pwd, PDO::PARAM_STR);
    $stmt->bindParam(":log_file", $master_status['File'], PDO::PARAM_STR);
    $stmt->bindParam(":log_pos", $master_status['Position'], PDO::PARAM_INT);
    $stmt->execute();

    $stmt = $pdo->prepare("START SLAVE;");
    $stmt->execute();
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

3. Implement HA solution and automatically switch master-slave nodes:

exec("ifconfig eth1:$vip $vip netmask 255.255.255.255"); 
exec("route add -host $vip dev eth1:$vip");

4. Implement automatic switching program and monitor the status of master-slave database:

$dsn = "mysql:host=$master_db_host;dbname=$master_db_name";
$user = $master_db_user;
$pwd = $master_db_pwd;

try {
    $pdo = new PDO($dsn, $user, $pwd);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->exec("SELECT 1 FROM DUAL;");
    $pdo = null;
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
    $dsn = "mysql:host=$slave_db_host;dbname=$slave_db_name";

    try {
        $pdo = new PDO($dsn, $slave_db_user, $slave_db_pwd);
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        exec("ifconfig eth1:$vip down");
        exec("ifconfig eth1:$vip up");
    } catch (PDOException $e) {
        echo 'Connection failed: ' . $e->getMessage();
    }
}

5. Implement the data recovery program and use the mysqldump command to export the data from the standby node to the failed node:

$cmd = "/usr/bin/mysqldump -h $slave_db_host -u $slave_db_user -p$slave_db_pwd $slave_db_name orders | mysql -h $master_db_host -u $master_db_user -p$master_db_pwd $master_db_name";

exec($cmd);

IV. Summary

Fault recovery of distributed architecture is more complicated than that of a stand-alone system. For shard database failures, we can use master-slave replication and HA solutions to achieve automatic switching and rapid data recovery. The above is the method and code implementation of database sharding fault recovery using PHP. I hope it will be helpful to readers in fault recovery under distributed architecture.

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