适用于 Node.js 的 chDB

如何安装和使用适用于 Node.js 的 chDB

chDB-node 为 chDB 提供了适用于 Node.js 的绑定，让你无需任何外部依赖即可在 Node.js 应用程序中直接运行 ClickHouse 查询。

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安装

npm install chdb

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用法

chDB-node 支持两种查询模式：适用于简单操作的独立查询，以及用于保持数据库状态的会话式查询。

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独立查询

对于简单的单次查询，如果不需要持久状态：

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

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

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

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

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

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会话式查询

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

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

try {
    // 创建数据库和表
    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', '[e-mail]'),
        (2, 'Bob', '[e-mail]'),
        (3, 'Charlie', '[e-mail]')
    `);

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

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

    // 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("User Statistics:", stats);

} finally {
    // 记得清理会话
    session.cleanup(); // 此操作将删除数据库文件
}

​

外部数据处理

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

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

try {
    // 从 URL 处理 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("External data analysis:", result);

    // 从外部数据创建表
    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("Daily analytics:", analysis);

} finally {
    session.cleanup();
}

​

错误处理

使用 chDB 时，务必正确处理错误：

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("Query error:", error.message);
        return { success: false, error: error.message };
    }
}

// 示例用法
const result = safeQuery("SELECT invalid_syntax");
if (result.success) {
    console.log("Query result:", result.data);
} else {
    console.log("Query failed:", result.error);
}

// 会话的错误处理
function safeSessionQuery() {
    const session = new Session("./error-test");
    
    try {
        // 由于语法无效，此处将抛出错误
        const result = session.query("CREATE TABLE invalid syntax", "CSV");
        console.log("Unexpected success:", result);
    } catch (error) {
        console.error("Session query error:", error.message);
    } finally {
        // 无论是否发生错误，始终执行清理操作
        session.cleanup();
    }
}

safeSessionQuery();

​

GitHub 仓库

• GitHub 仓库: chdb-io/chdb-node
• 问题反馈与支持: 请在 GitHub 仓库 上报告问题
• NPM 包: npm 上的 chdb