QuestDB Node.js Client

Requirements

The client requires Node.js v16 or newer version.

Installation

npm i -s @questdb/nodejs-client

Configuration options

Detailed description of the client's configuration options can be found in the SenderOptions documentation.

Examples

The examples below demonstrate how to use the client. For more details, please, check the Sender's documentation.

Basic API usage

const { Sender } = require('@questdb/nodejs-client');

async function run() {
    // create a sender using HTTP protocol
    const sender = Sender.fromConfig('http::addr=localhost:9000');

    // add rows to the buffer of the sender
    await sender.table('prices').symbol('instrument', 'EURUSD')
        .floatColumn('bid', 1.0195).floatColumn('ask', 1.0221)
        .at(Date.now(), 'ms');
    await sender.table('prices').symbol('instrument', 'GBPUSD')
        .floatColumn('bid', 1.2076).floatColumn('ask', 1.2082)
        .at(Date.now(), 'ms');

    // flush the buffer of the sender, sending the data to QuestDB
    // the buffer is cleared after the data is sent, and the sender is ready to accept new data
    await sender.flush();

    // add rows to the buffer again, and send it to the server
    await sender.table('prices').symbol('instrument', 'EURUSD')
        .floatColumn('bid', 1.0197).floatColumn('ask', 1.0224)
        .at(Date.now(), 'ms');
    await sender.flush();

    // close the connection after all rows ingested
    await sender.close();
}

run()
    .then(console.log)
    .catch(console.error);

Authentication and secure connection

const { Sender } = require('@questdb/nodejs-client');

async function run() {
    // create a sender using HTTPS protocol with username and password authentication
    const sender = Sender.fromConfig('https::addr=localhost:9000;username=user1;password=pwd');

    // send the data over the authenticated and secure connection
    await sender.table('prices').symbol('instrument', 'EURUSD')
        .floatColumn('bid', 1.0197).floatColumn('ask', 1.0224)
        .at(Date.now(), 'ms');
    await sender.flush();

    // close the connection after all rows ingested
    await sender.close();
}

run().catch(console.error);

TypeScript example

import { Sender } from '@questdb/nodejs-client';

async function run(): Promise<number> {
    // create a sender using HTTPS protocol with bearer token authentication
    const sender: Sender = Sender.fromConfig('https::addr=localhost:9000;token=Xyvd3er6GF87ysaHk');

    // send the data over the authenticated and secure connection
    sender.table('prices').symbol('instrument', 'EURUSD')
        .floatColumn('bid', 1.0197).floatColumn('ask', 1.0224).at(Date.now(), 'ms');
    await sender.flush();

    // close the connection after all rows ingested
    await sender.close();
}

run().catch(console.error);

Worker threads example

const { Sender } = require('@questdb/nodejs-client');
const { Worker, isMainThread, parentPort, workerData } = require('worker_threads');

// fake venue
// generates random prices for a ticker for max 5 seconds, then the feed closes
function* venue(ticker) {
    let end = false;
    setTimeout(() => { end = true; }, rndInt(5000));
    while (!end) {
        yield {'ticker': ticker, 'price': Math.random()};
    }
}

// market data feed simulator
// uses the fake venue to deliver price updates to the feed handler (onTick() callback)
async function subscribe(ticker, onTick) {
    const feed = venue(workerData.ticker);
    let tick;
    while (tick = feed.next().value) {
        await onTick(tick);
        await sleep(rndInt(30));
    }
}

async function run() {
    if (isMainThread) {
        const tickers = ['t1', 't2', 't3', 't4'];
        // main thread to start a worker thread for each ticker
        for (let ticker in tickers) {
            const worker = new Worker(__filename, { workerData: { ticker: ticker } })
                .on('error', (err) => { throw err; })
                .on('exit', () => { console.log(`${ticker} thread exiting...`); })
                .on('message', (msg) => {
                    console.log(`Ingested ${msg.count} prices for ticker ${msg.ticker}`);
                });
        }
    } else {
        // it is important that each worker has a dedicated sender object
        // threads cannot share the sender because they would write into the same buffer
        const sender = Sender.fromConfig('http::addr=localhost:9000');

        // subscribe for the market data of the ticker assigned to the worker
        // ingest each price update into the database using the sender
        let count = 0;
        await subscribe(workerData.ticker, async (tick) => {
            await sender
                .table('prices')
                .symbol('ticker', tick.ticker)
                .floatColumn('price', tick.price)
                .at(Date.now(), 'ms');
            await sender.flush();
            count++;
        });

        // let the main thread know how many prices were ingested
        parentPort.postMessage({'ticker': workerData.ticker, 'count': count});

        // close the connection to the database
        await sender.close();
    }
}

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

function rndInt(limit) {
    return Math.floor((Math.random() * limit) + 1);
}

run()
    .then(console.log)
    .catch(console.error);