Implementation of PDO-based sessions in PHP (MySQL/MariaDB-only for now)

pdo_sessions.php

<?php
/* Schema
CREATE TABLE php_sessions (
    id VARCHAR(32) NOT NULL PRIMARY KEY,
    access BIGINT NOT NULL,
    data BLOB NOT NULL
);
 */

class PDOBackedSession implements SessionHandlerInterface {
    public function __construct($dsn, $user = null, $pass = null, $options = []) {
        $this->dsn = $dsn;
        $this->user = $user;
        $this->pass = $pass;
        $this->options = array_merge([
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
        ], $options);
    }

    public function register() {
        session_set_save_handler($this, true);
    }

    public function open($path, $name) {
        try {
            $this->pdo = new PDO($this->dsn, $this->user, $this->pass, $this->options);
            return true;
        } catch (PDOException $e) {
            return false;
        }
    }

    public function close() {
        $this->pdo = null;
        return true;
    }

    public function read($sid) {
        $stmt = $this->pdo->prepare('SELECT data FROM php_sessions WHERE id = ?');
        $stmt->execute([$sid]);
        $result = $stmt->fetch(PDO::FETCH_ASSOC);
        return $result ? $result['data'] : '';
    }

    public function write($sid, $data) {
        $stmt = $this->pdo->prepare('REPLACE INTO php_sessions VALUES (?, ?, ?)');
        $stmt->execute([$sid, time(), $data]);
        return true;
    }

    public function destroy($sid) {
        $stmt = $this->pdo->prepare('DELETE FROM php_sessions WHERE id = ?');
        $stmt->execute([$sid]);
        return true;
    }

    public function gc($lifetime) {
        $stmt = $this->pdo->prepare('DELETE FROM php_sessions WHERE access < ?');
        $stmt->execute([time() - $lifetime]);
        return true;
    }
}