Real-time data synchronization and replication using PHP and SQLite

Title: Real-time data synchronization and replication using PHP and SQLite

Introduction:
In today's information age, real-time synchronization and replication of data are becoming more and more important. Whether it is data synchronization within an enterprise or data replication between multiple systems, an efficient and reliable method is required to achieve it. This article will introduce how to use PHP and SQLite to achieve real-time data synchronization and replication, and provide corresponding code examples.

1. Introducing SQLite and PHP extensions
First, we need to ensure that the SQLite database has been installed in the system and associate it with the PHP extension. SQLite and PHP extensions can be installed through the following commands:

sudo apt-get install sqlite3
sudo apt-get install php-sqlite3

2. Create the master database and slave database
Before starting, we need to create a master database and a slave database. Database files can be created using SQLite's command line tools or visual tools. Suppose we create a master database named "main.db" and a slave database named "replica.db".

3. Write a data synchronization script
Next, we will write a PHP script to achieve real-time synchronization between the master database and the slave database. The specific code is as follows:

<?php
// 连接主数据库
$mainDb = new SQLite3('main.db');

// 连接从数据库
$replicaDb = new SQLite3('replica.db');

// 获取主数据库中最后更新的时间戳
$lastTimestamp = $replicaDb->querySingle("SELECT max(timestamp) FROM data");

// 查询主数据库中大于该时间戳的数据
$query = "SELECT * FROM data WHERE timestamp > '{$lastTimestamp}'";
$result = $mainDb->query($query);

// 将查询结果插入从数据库中
while ($row = $result->fetchArray()) {
    $query = "INSERT INTO data VALUES ('{$row['data']}', '{$row['timestamp']}')";
    $replicaDb->exec($query);
}

The above code mainly includes the following operations:

1. Connecting the master database and the slave database is implemented through the SQLite3 class.
2. Get the last updated timestamp in the slave database, which is used to query the latest data in the master database.
3. Query the data in the main database that is greater than the timestamp.
4. Insert query results into the database.

4. Implement automatic data replication
In order to achieve real-time synchronization and replication of data, we can use scheduled tasks to automatically run the above PHP script. Scheduled tasks can be set up through the crontab command. The sample code is as follows:

*/5 * * * * /usr/bin/php /path/to/sync_script.php >> /path/to/log.txt

The above code means executing the sync_script.php script every 5 minutes and saving the output results to the log.txt log file. You can adjust it according to your needs.

Summary:
This article introduces how to use PHP and SQLite to achieve real-time data synchronization and replication, and provides corresponding code examples. By running PHP scripts regularly, we can achieve data synchronization between the master database and the slave database to ensure real-time consistency of the data. This method is suitable for small applications and systems and is simple, efficient and reliable. Of course, for large-scale systems, other more powerful database synchronization and replication tools can be considered for implementation.

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