Integration of PHP and database distribution

With the development of Internet technology, for a network application, operations on the database are very frequent. Especially for dynamic websites, there may even be hundreds of database requests per second. When the database processing capacity cannot meet the demand, we can consider using database distribution. The implementation of distributed databases is inseparable from integration with programming languages.

As a very popular programming language, PHP has good applicability and flexibility. This article will focus on the practice of distributed integration of PHP and database.

1. The concept of distribution

The essence of distribution is the allocation of resources. Here we refer to distributed databases, which means splitting a database into multiple databases and distributing them to multiple servers. These databases work together through certain means to achieve higher concurrent processing capabilities and stronger scalability. and higher fault tolerance. Here we can understand that in a project, databases on multiple servers can respond simultaneously to achieve the purpose of improving work efficiency and ensuring availability.

2. How to implement database distribution

There are two main ways to implement database distribution.

2.1 Partition

This method is actually to divide the data into multiple partitions according to the data range or according to certain algorithms, and then store them on different database servers. Each database server only processes part of the data. Partitioning can increase the scalability and fault tolerance of the system, but requires some extra work for the client.

2.2 Replication

Data replication ensures data availability and fault tolerance by writing data to multiple locations. There are two main methods, namely "master-slave" replication and peer-to-peer replication. In master-slave replication, a master database receives write operations, and the master database asynchronously replicates these operations to one or more slave databases. In peer-to-peer replication, each database can change data, and changes made by each database are replicated asynchronously to the other databases.

3. Realization of distributed integration of PHP and database

3.1 Single node operation

Through PHP’s mysqli and pdo extensions, we can perform operations on a single node operate. This method is very simple, we only need to connect to a database, perform data operations, and then get the results.

For example:

// 使用mysqli扩展连接数据库
$mysqli = new mysqli("localhost", "my_user", "my_password", "testdb");

// 检查连接
if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}

// 执行查询
$result = $mysqli->query("SELECT * FROM mytable");

// 遍历结果集
while($row = $result->fetch_assoc()) {
    echo $row["id"] . " " . $row["name"];
}

// 关闭连接
$mysqli->close();

3.2 Partition operation

If we want to operate on the partitioned database, we need to redistribute and reorganize the query, which requires code changes Make more complex changes. This process is query routing, which routes queries to the correct location in the partitioned database.

For example:

// 使用mysqli扩展连接一个分区数据库
$mysqli = new mysqli("shard1.example.com", "my_user", "my_password", "testdb");

// 执行查询
$result = $mysqli->query("SELECT * FROM mytable WHERE id = 1");

// 关闭连接
$mysqli->close();

However, for performing complex operations or queries in multiple databases, you need to use some algorithms such as hash functions for automatic partitioning.

For example:

// 根据用户ID计算哈希值，路由到对应的分区数据库中执行
$partition = md5($user_id) % 4;
$mysqli = new mysqli("shard{$partition}.example.com", "my_user", "my_password", "testdb");

// 执行查询
$result = $mysqli->query("SELECT * FROM mytable WHERE user_id = $user_id");

// 关闭连接
$mysqli->close();

3.3 Copy operation

For database replication, the corresponding API is also provided in PHP, that is, to write to multiple databases, you need to use Mysqli's multi_query() function and PDO's exec() function are used to execute multiple SQL statements. Read operations can be performed like single-node operations.

For example:

// 使用mysqli扩展连接主数据库
$mysqli = new mysqli("master.example.com", "my_user", "my_password", "testdb");

// 执行多个写操作
$mysqli->multi_query("
    INSERT INTO mytable (name, age) VALUES ('Tom', 20);
    UPDATE mytable SET age = 21 WHERE name = 'Tom';
    DELETE FROM mytable WHERE name = 'Jerry';
");

// 关闭连接
$mysqli->close();

4. Summary

PHP is a programming language that is very suitable for distributed integration with databases. It provides a variety of extensions, It is very easy to interact with the database. When using a distributed database, we need to redistribute and reorganize queries. Especially when operating complex queries, we need to use algorithms such as hash functions for automatic partitioning.

At the same time, due to some problems in distributed databases, such as master-slave data inconsistency, writing delays, etc., corresponding solutions need to be designed for different situations. However, through appropriate implementation and tuning, distributed databases can effectively improve the system's concurrent processing capabilities, scalability, and fault tolerance, and are an important tool for modern high-performance applications.

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