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适用于 Node.js 的 chDB

chDB-node 为 chDB 提供了 Node.js 绑定，让你能够在 Node.js 应用中直接运行 ClickHouse 查询，而无需任何外部依赖。

安装​

npm 安装 chdb

用法​

chDB-node 支持两种查询模式：用于简单操作的独立查询，以及用于维护数据库状态的会话查询。

独立查询​

适用于不需要持久状态的简单一次性查询：

const { query } = require("chdb");

// 基本查询
const result = query("SELECT version()", "CSV");
console.log("ClickHouse 版本：", result);

// 多列查询
const multiResult = query("SELECT 'Hello' as greeting, 'chDB' as engine, 42 as answer", "CSV");
console.log("多列结果：", multiResult);

// 数学运算
const mathResult = query("SELECT 2 + 2 as sum, pi() as pi_value", "JSON");
console.log("数学运算结果：", mathResult);

// 系统信息
const systemInfo = query("SELECT * FROM system.functions LIMIT 5", "Pretty");
console.log("系统函数：", systemInfo);

基于会话的查询​

const { Session } = require("chdb");

// 创建一个带持久化存储的会话
const session = new Session("./chdb-node-data");

try {
    // 创建数据库和数据表
    session.query(`
        CREATE DATABASE IF NOT EXISTS myapp;
        CREATE TABLE IF NOT EXISTS myapp.users (
            id UInt32,
            name String,
            email String,
            created_at DateTime DEFAULT now()
        ) ENGINE = MergeTree() ORDER BY id
    `);

    // 插入示例数据
    session.query(`
        INSERT INTO myapp.users (id, name, email) VALUES 
        (1, 'Alice', '[email protected]'),
        (2, 'Bob', '[email protected]'),
        (3, 'Charlie', '[email protected]')
    `);

    // 以不同格式查询数据
    const csvResult = session.query("SELECT * FROM myapp.users ORDER BY id", "CSV");
    console.log("CSV 结果：", csvResult);

    const jsonResult = session.query("SELECT * FROM myapp.users ORDER BY id", "JSON");
    console.log("JSON 结果：", jsonResult);

    // 执行聚合查询
    const stats = session.query(`
        SELECT 
            COUNT(*) as total_users,
            MAX(id) as max_id,
            MIN(created_at) as earliest_signup
        FROM myapp.users
    `, "Pretty");
    console.log("用户统计信息：", stats);

} finally {
    // 务必清理会话
    session.cleanup(); // 这将删除数据库文件
}

处理外部数据​

const { Session } = require("chdb");

const session = new Session("./data-processing");

try {
    // 处理来自 URL 的 CSV 数据
    const result = session.query(`
        SELECT 
            COUNT(*) as total_records,
            COUNT(DISTINCT "UserID") as unique_users
        FROM url('https://datasets.clickhouse.com/hits/hits.csv', 'CSV') 
        LIMIT 1000
    `, "JSON");
    
    console.log("外部数据分析：", result);

    // 基于外部数据创建表
    session.query(`
        CREATE TABLE web_analytics AS
        SELECT * FROM url('https://datasets.clickhouse.com/hits/hits.csv', 'CSV')
        LIMIT 10000
    `);

    // 分析导入的数据
    const analysis = session.query(`
        SELECT 
            toDate("EventTime") as date,
            COUNT(*) as events,
            COUNT(DISTINCT "UserID") as unique_users
        FROM web_analytics
        GROUP BY date
        ORDER BY date
        LIMIT 10
    `, "Pretty");
    
    console.log("每日数据分析：", analysis);

} finally {
    session.cleanup();
}

错误处理​

在使用 chDB 时，请务必妥善处理错误：

const { query, Session } = require("chdb");

// 独立查询的错误处理
function safeQuery(sql, format = "CSV") {
    try {
        const result = query(sql, format);
        return { success: true, data: result };
    } catch (error) {
        console.error("查询出错：", error.message);
        return { success: false, error: error.message };
    }
}

// 使用示例
const result = safeQuery("SELECT invalid_syntax");
if (result.success) {
    console.log("查询结果：", result.data);
} else {
    console.log("查询失败：", result.error);
}

// 会话查询的错误处理
function safeSessionQuery() {
    const session = new Session("./error-test");
    
    try {
        // 由于语法错误，这里会抛出异常
        const result = session.query("CREATE TABLE invalid syntax", "CSV");
        console.log("出现意外的成功：", result);
    } catch (error) {
        console.error("会话查询出错：", error.message);
    } finally {
        // 无论是否发生错误都要执行清理
        session.cleanup();
    }
}

safeSessionQuery();

GitHub 仓库​