# Connecting to CrateDB with Node.js

**URL:** https://community.cratedb.com/t/connecting-to-cratedb-with-node-js/751
**Category:** Tutorials
**Tags:** integration
**Created:** [July 25, 2021, 10:00pm UTC](https://community.cratedb.com/t/connecting-to-cratedb-with-node-js/751 "2021-07-25T22:00:00Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![jayeff](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/jayeff/32/271_2.png) [@jayeff](https://community.cratedb.com/u/jayeff)
#### Post date: [July 25, 2021, 10:00pm UTC](https://community.cratedb.com/t/connecting-to-cratedb-with-node-js/751/1 "2021-07-25T22:00:00Z")

</div>

This article describes how to connect to CrateDB from Node.js using the [node-postgres](https://node-postgres.com/) driver.

# Prerequisites

Install the node package to use the driver

```auto
npm install pg

```

# Connecting to CrateDB

Launch a [free trial cluster on CrateDB Cloud](https://crate.io/products/cratedb-cloud/) or start CrateDB locally (e.g. [launch with Docker](https://crate.io/docs/crate/tutorials/en/latest/install.html#docker)) to have a CrateDB cluster to connect to.

Afterwards start the following script to connect and execute a simple test query against CrateDB:

```auto
const { Pool } = require('pg');

const CRATE_CONNECTION_STRING = 'postgres://crate@localhost:5432';
const statement = 'SELECT id, hostname FROM sys.nodes LIMIT 1';

const cratePool = new Pool({
    connectionString: CRATE_CONNECTION_STRING,
    idleTimeoutMillis: 15000,
    connectionTimeoutMillis: 5000,
    query_timeout: 30000,
});

cratePool.connect((err, client, release) => {
    if (err) {
        return console.error('Error acquiring client', err.stack);
    }
    client.query(statement, (err, result) => {
        release();
        if (err) {
            return console.error('Error executing query', err.stack);
        }
        console.log(result.rows);
    })
})

cratePool.end();

```

# Ingesting into CrateDB with UNNEST

For achieving high ingest performance it’s suggested to use the UNNEST [approach](https://crate.io/docs/crate/howtos/en/latest/performance/inserts/methods.html#unnest) with node-postgres. The following example shows this method:

```auto
const { Pool } = require('pg');

// create test table with following query:
// CREATE TABLE events(ts TIMESTAMP, payload OBJECT);

const CRATE_CONNECTION_STRING = 'postgres://crate@localhost:5432/doc';
const TABLE = 'doc.events';
const COLUMNS = ['ts', 'payload'];

const cratePool = new Pool({
    connectionString: CRATE_CONNECTION_STRING,
    idleTimeoutMillis: 15000,
    connectionTimeoutMillis: 5000,
    database: 'doc',
    query_timeout: 30000,
});

// generate sample data
let ts = Date.now();
let timestamps = [];
let payloads = [];
for (let i = 0; i < 200; i++) {
    timestamps.push(ts + i*1000);
    payloads.push(`{"element": ${i}}`);
}

const statement = `INSERT INTO ${TABLE} ("${COLUMNS.join('","')}") 
    (SELECT * FROM UNNEST ( $1::array(long), $2::array(object) ));`;
const values = [timestamps, payloads];

cratePool.connect((err, client, release) => {
    if (err) {
        return console.error('Error acquiring client', err.stack);
    }
    client.query(statement, values, (err, result) => {
        release();
        if (err) {
            return console.error('Error executing query', err.stack);
        }
        console.log(`Successfully inserted ${result.rowCount} rows`);
    })
})

cratePool.end();

```

Please note that with this approach CrateDB will drop rows which would produce an error e.g. due to an incorrect data type.

# Ingesting into CrateDB with multiple value expression

An alternative to the UNNEST approach above is to use [multiple value expression](https://crate.io/docs/crate/howtos/en/latest/performance/inserts/methods.html#multiple-value-expressions).

```auto
const { Pool } = require('pg');

const CRATE_CONNECTION_STRING = 'postgres://crate@localhost:5432';
const TABLE = 'doc.events';
const COLUMNS = ['ts', 'payload'];

const cratePool = new Pool({
    connectionString: CRATE_CONNECTION_STRING,
    idleTimeoutMillis: 15000,
    connectionTimeoutMillis: 5000,
    query_timeout: 30000,
});

let ts = Date.now();
let query = `INSERT INTO ${TABLE} ("${COLUMNS.join('","')}") VALUES `;
for (let i = 0; i < 200; i++) {
    if (i > 0) query += `,`;
    query += `('${ts + i*1000}','{"element": ${i}}')`;
}
query += ';';

cratePool.connect((err, client, release) => {
    if (err) {
        return console.error('Error acquiring client', err.stack);
    }
    client.query(query, (err, result) => {
        release();
        if (err) {
            return console.error('Error executing query', err.stack);
        }
        console.log(`Successfully inserted ${result.rowCount} rows`);
    });
});

cratePool.end();

```

# Notice

When working with JavaScript, pay attention to integers outside the safe range (smaller than -9007199254740991 or larger than 9007199254740991). Outside this range, JavaScript cannot represent integers reliably due to the internal representation as 64-bit floating-point value and you will lose precision.