How to implement distributed query and indexing in PHP microservices

How to implement distributed query and indexing in PHP microservices

With the development of Internet applications, the amount of data is increasing, and a single-machine database can no longer satisfy the query and indexing requirements. Distributed query and indexing became one of the solutions. This article will introduce how to implement distributed query and indexing in PHP microservices and provide specific code examples.

1. Data fragmentation and distributed query

In distributed query, data fragmentation is very important. Data sharding stores data dispersedly on multiple nodes, and each node only stores part of the data, which can reduce the load pressure on a single node. In PHP microservices, the hash sharding algorithm can be used to spread data to different database nodes.

Suppose there is a user table that contains fields such as the user's ID, name, and age. First, you need to determine the number of shards, which can be calculated based on the hash value of the user ID. Assuming that the number of shards is 3, you can use the following method to calculate the shard number:

function shard($id, $shardCount) {
    return crc32($id) % $shardCount;
}

Assume that the user ID is 1001, you can use the following code to get the shard number where the user is:

$shardCount = 3;
$userId = 1001;
$shardId = shard($userId, $shardCount);

Then , you can connect to the corresponding database node for query based on the obtained shard number:

$databaseConfig = [
    ['host' => 'node1', 'user' => 'root', 'password' => 'password', 'database' => 'shard1'],
    ['host' => 'node2', 'user' => 'root', 'password' => 'password', 'database' => 'shard2'],
    ['host' => 'node3', 'user' => 'root', 'password' => 'password', 'database' => 'shard3'],
];

$connection = new PDO("mysql:host={$databaseConfig[$shardId]['host']};dbname={$databaseConfig[$shardId]['database']}", $databaseConfig[$shardId]['user'], $databaseConfig[$shardId]['password']);

// 查询用户信息
$userId = 1001;
$query = $connection->prepare("SELECT * FROM user WHERE id = :id");
$query->bindParam(':id', $userId);
$query->execute();

$user = $query->fetch(PDO::FETCH_ASSOC);

2. Distributed Index

In distributed query, use shards to process data Query can reduce the load pressure on a single node, but in some cases there will still be a performance bottleneck. For example, when performing a fuzzy query on a certain field, all nodes need to be traversed for matching, which is inefficient.

To solve this problem, distributed indexes can be used. Distributed indexes store index data dispersedly on multiple nodes, and each node only stores part of the index data. In PHP microservices, Redis can be used as distributed index storage.

Assuming that you want to create a distributed index on the name field of the user table, you can use the following method:

$redisConfig = [
    ['host' => 'node1', 'port' => 6379],
    ['host' => 'node2', 'port' => 6379],
    ['host' => 'node3', 'port' => 6379],
];

$redis = new Redis();
$redis->connect($redisConfig[$shardId]['host'], $redisConfig[$shardId]['port']);

// 建立索引
$userId = 1001;
$userName = 'John';

$redis->sAdd("index:user:name:$userName", $userId);

Then, you can use the index to complete the distributed query:

$userName = 'John';

// 获取索引中保存的用户ID
$userIdSet = $redis->sMembers("index:user:name:$userName");

// 查询用户信息
$query = $connection->prepare("SELECT * FROM user WHERE id IN (" . implode(',', $userIdSet) . ")");
$query->execute();

$users = $query->fetchAll(PDO::FETCH_ASSOC);

Pass The above code example can implement distributed query and indexing in PHP microservices. Using data sharding and distributed indexes can improve query and index performance, and can be horizontally expanded by adding nodes to meet growing data storage needs. At the same time, attention needs to be paid to issues such as data consistency and fault recovery to ensure the stability and reliability of the distributed system.

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