Query HDFS Data through ODBC in Node.js

Node.js is a JavaScript runtime environment that allows you to run JavaScript code outside of a browser. With the CData ODBC Driver for HDFS, you can access live HDFS data from Node.js apps and scripts. In this article, we walk through installing node-odbc and the required tools to create a simple Node.js app with access to live HDFS data.

With built-in optimized data processing, the CData ODBC Driver offers unmatched performance for interacting with live HDFS data in Node.js. When you issue complex SQL queries from Node.js to HDFS, the driver pushes supported SQL operations, like filters and aggregations, directly to HDFS and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations).

Connecting to HDFS Data

If you have not already done so, provide values for the required connection properties in the data source name (DSN). You can use the built-in Microsoft ODBC Data Source Administrator to configure the DSN. This is also the last step of the driver installation. See the "Getting Started" chapter in the help documentation for a guide to using the Microsoft ODBC Data Source Administrator to create and configure a DSN.

In order to authenticate, set the following connection properties:

• Host: Set this value to the host of your HDFS installation.
• Port: Set this value to the port of your HDFS installation. Default port: 50070

Building node-odbc

In order to connect to HDFS through the CData ODBC Driver, you need to build node-odbc manually (after installing the required tools).

Installing the Required Tools

The following commands install the tools required to build node-odbc (note the -g parameter, which installs the tools globally).

npm i -g windows-build-tools
npm i -g node-gyp

Building node-odbc

After installing the required tools, create a directory for the Node.js app and install odbc (which builds the binary for us to use in our Node.js script).

mkdir nodeodbc
cd nodeodbc
npm i -g node

Querying HDFS from Node.js

With the ODBC Driver installed, a DSN Configured, and node-odbc built, we are ready to query live HDFS data from a Node.js app. The sample code below connects to a specific DSN and queries the Files table.

myscript.js

const odbc = require('odbc');

async function queryHDFS() {
 const connection = await odbc.connect(`DSN=CData HDFS Source`);
 const data = await connection.query('SELECT FileId, ChildrenNum FROM Files');
 console.log(data);
}

queryHDFS();

Once you write the app, use node to execute the script:

node myscript.js

Download a free, 30-day trial of the CData ODBC Driver for HDFS and start working with your live HDFS data in Node.js. Reach out to our Support Team if you have any questions.