PHP中如何实现数据分片？

function getShard($userId) {
    $shardCount = 10; // 假设我们有10个分片
    return $userId % $shardCount;
}

function getDatabaseName($shardId) {
    return "db_shard_" . $shardId;
}

$userId = 12345;
$shardId = getShard($userId);
$dbName = getDatabaseName($shardId);
echo "User ID $userId is stored in database $dbName";

function getRangeShard($timestamp) {
    $ranges = [
        ['start' => 0, 'end' => 1593561600, 'shard' => 0],
        ['start' => 1593561601, 'end' => 1625097600, 'shard' => 1],
        // 更多范围...
    ];

    foreach ($ranges as $range) {
        if ($timestamp >= $range['start'] && $timestamp <= $range['end']) {
            return $range['shard'];
        }
    }

    return -1; // 未找到合适的分片
}

$timestamp = time();
$shardId = getRangeShard($timestamp);
if ($shardId !== -1) {
    $dbName = getDatabaseName($shardId);
    echo "Timestamp $timestamp is stored in database $dbName";
} else {
    echo "No shard found for timestamp $timestamp";
}

class ConsistentHash {
    private $nodes = [];
    private $ring = [];

    public function __construct($nodes) {
        foreach ($nodes as $node) {
            $this->addNode($node);
        }
    }

    private function addNode($node) {
        $hash = $this->hash($node);
        $this->nodes[$hash] = $node;
        $this->ring[] = $hash;
        sort($this->ring);
    }

    private function hash($key) {
        return crc32($key);
    }

    public function getNode($key) {
        $hash = $this->hash($key);
        $index = $this->findIndex($hash);
        return $this->nodes[$this->ring[$index]];
    }

    private function findIndex($hash) {
        foreach ($this->ring as $index => $ringHash) {
            if ($hash <= $ringHash) {
                return $index;
            }
        }
        return 0;
    }
}

$nodes = ['node1', 'node2', 'node3'];
$hashRing = new ConsistentHash($nodes);

$key = 'user123';
$node = $hashRing->getNode($key);
echo "Key $key is stored in node $node";

class ShardRouter {
    private $shards = [];

    public function __construct($shards) {
        $this->shards = $shards;
    }

    public function query($userId, $query) {
        $shardId = getShard($userId);
        $dbName = getDatabaseName($shardId);
        $pdo = new PDO("mysql:host=localhost;dbname=$dbName", 'username', 'password');
        $stmt = $pdo->prepare($query);
        $stmt->execute();
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }
}

$shards = [
    0 => 'db_shard_0',
    1 => 'db_shard_1',
    // 更多分片...
];

$router = new ShardRouter($shards);
$userId = 12345;
$query = "SELECT * FROM users WHERE id = :id";
$results = $router->query($userId, $query);
print_r($results);

class TransactionManager {
    private $shards = [];

    public function __construct($shards) {
        $this->shards = $shards;
    }

    public function startTransaction($userId) {
        $shardId = getShard($userId);
        $dbName = getDatabaseName($shardId);
        $pdo = new PDO("mysql:host=localhost;dbname=$dbName", 'username', 'password');
        $pdo->beginTransaction();
        return $pdo;
    }

    public function commitTransaction($pdo) {
        $pdo->commit();
    }

    public function rollbackTransaction($pdo) {
        $pdo->rollBack();
    }
}

$shards = [
    0 => 'db_shard_0',
    1 => 'db_shard_1',
    // 更多分片...
];

$manager = new TransactionManager($shards);
$userId = 12345;
$pdo = $manager->startTransaction($userId);
try {
    // 执行事务操作
    $pdo->exec("INSERT INTO users (id, name) VALUES (12345, 'John Doe')");
    $manager->commitTransaction($pdo);
} catch (Exception $e) {
    $manager->rollbackTransaction($pdo);
    echo "Transaction failed: " . $e->getMessage();
}