Databricks SQL Driver for Node.js

The Databricks SQL Driver for Node.js is a Node.js library that allows you to use JavaScript code to run SQL commands on Databricks compute resources.

Requirements

  • A development machine running Node.js, version 14 or higher. To print the installed version of Node.js, run the command node -v. To install and use different versions of Node.js, you can use tools such as Node Version Manager (nvm).

  • Node Package Manager (npm). Later versions of Node.js already include npm. To check whether npm is installed, run the command npm -v. To install npm if needed, you can follow instructions such as the ones at Download and install npm.

  • The @databricks/sql package from npm. To install the @databricks/sql package in your Node.js project as a dependency, use npm to run the following command from within the same directory as your project:

    npm i @databricks/sql
    
  • If you want to install and use TypeScript in your Node.js project as devDependencies, use npm to run the following commands from within the same directory as your project:

    npm i -D typescript
    npm i -D @types/node
    
  • An existing cluster or SQL warehouse.

  • The Server Hostname and HTTP Path value for the existing cluster or SQL warehouse.

Authentication

The Databricks SQL Driver for Node.js supports the following Databricks authentication types:

The Databricks SQL Driver for Node.js does not yet support the following Databricks authentication types:

Note

As a security best practice, you should not hard code connection variable values into your code. Instead, you should retrieve these connection variable values from a secure location. For example, the code snippets and examples in this article use environment variables.

Databricks personal access token authentication

To use the Databricks SQL Driver for Node.js with Databricks personal access token authentication, you must first create a Databricks personal access token, as follows:

  1. In your Databricks workspace, click your Databricks username in the top bar, and then select User Settings from the drop down.

  2. Click Developer.

  3. Next to Access tokens, click Manage.

  4. Click Generate new token.

  5. (Optional) Enter a comment that helps you to identify this token in the future, and change the token’s default lifetime of 90 days. To create a token with no lifetime (not recommended), leave the Lifetime (days) box empty (blank).

  6. Click Generate.

  7. Copy the displayed token to a secure location, and then click Done.

Note

Be sure to save the copied token in a secure location. Do not share your copied token with others. If you lose the copied token, you cannot regenerate that exact same token. Instead, you must repeat this procedure to create a new token. If you lose the copied token, or you believe that the token has been compromised, Databricks strongly recommends that you immediately delete that token from your workspace by clicking the trash can (Revoke) icon next to the token on the Access tokens page.

If you are not able to create or use tokens in your workspace, this might be because your workspace administrator has disabled tokens or has not given you permission to create or use tokens. See your workspace administrator or the following:

To authenticate the Databricks SQL Driver for Node.js, use the following code snippet. This snippet assumes that you have set the following environment variables:

  • DATABRICKS_SERVER_HOSTNAMEset to the Server Hostname value for your cluster or SQL warehouse.

  • DATABRICKS_HTTP_PATH, set to HTTP Path value for your cluster or SQL warehouse.

  • DATABRICKS_TOKEN, set to the Databricks personal access token.

To set environment variables, see your operating system’s documentation.

const { DBSQLClient } = require('@databricks/sql');

const serverHostname = process.env.DATABRICKS_SERVER_HOSTNAME;
const httpPath       = process.env.DATABRICKS_HTTP_PATH;
const token          = process.env.DATABRICKS_TOKEN;

if (!token || !serverHostname || !httpPath) {
    throw new Error("Cannot find Server Hostname, HTTP Path, or " +
                    "personal access token. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME, " +
                    "DATABRICKS_HTTP_PATH, and DATABRICKS_TOKEN.");
  }

  const client = new DBSQLClient();
  const connectOptions = {
    token: token,
    host:  serverHostname,
    path:  httpPath
  };

  client.connect(connectOptions)
  // ...
import { DBSQLClient } from "@databricks/sql";

const serverHostname: string = process.env.DATABRICKS_SERVER_HOSTNAME || '';
const httpPath: string       = process.env.DATABRICKS_HTTP_PATH || '';
const token: string          = process.env.DATABRICKS_TOKEN || '';

if (token == '' || serverHostname == '' || httpPath == '') {
    throw new Error("Cannot find Server Hostname, HTTP Path, or personal access token. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME, " +
                    "DATABRICKS_HTTP_PATH, and DATABRICKS_TOKEN.");
  }

  const client: DBSQLClient = new DBSQLClient();
  const connectOptions = {
    token: token,
    host:  serverHostname,
    path:  httpPath
  };

  client.connect(connectOptions)
  // ...

OAuth user-to-machine (U2M) authentication

Databricks SQL Driver for Node.js versions 1.8.0 and above support OAuth user-to-machine (U2M) authentication.

To authenticate the Databricks SQL Driver for Node.js with OAuth U2M authentication, use the following code snippet. This snippet assumes that you have set the following environment variables:

  • DATABRICKS_SERVER_HOSTNAMEset to the Server Hostname value for your cluster or SQL warehouse.

  • DATABRICKS_HTTP_PATH, set to HTTP Path value for your cluster or SQL warehouse.

To set environment variables, see your operating system’s documentation.

const { DBSQLClient } = require('@databricks/sql');

const serverHostname = process.env.DATABRICKS_SERVER_HOSTNAME;
const httpPath       = process.env.DATABRICKS_HTTP_PATH;

if (!serverHostname || !httpPath) {
    throw new Error("Cannot find Server Hostname or HTTP Path. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME " +
                    "and DATABRICKS_HTTP_PATH.");
  }

  const client = new DBSQLClient();
  const connectOptions = {
    authType: "databricks-oauth",
    host:     serverHostname,
    path:     httpPath
  };

  client.connect(connectOptions)
  // ...
import { DBSQLClient } from "@databricks/sql";

const serverHostname: string = process.env.DATABRICKS_SERVER_HOSTNAME || '';
const httpPath: string       = process.env.DATABRICKS_HTTP_PATH || '';

if (serverHostname == '' || httpPath == '') {
    throw new Error("Cannot find Server Hostname or HTTP Path. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME " +
                    "and DATABRICKS_HTTP_PATH.");
  }

  const client: DBSQLClient = new DBSQLClient();
  const connectOptions = {
    authType: "databricks-oauth",
    host:     serverHostname,
    path:     httpPath
  };

  client.connect(connectOptions)
  // ...

OAuth machine-to-machine (M2M) authentication

Databricks SQL Driver for Node.js versions 1.8.0 and above support OAuth machine-to-machine (U2M) authentication.

To use the Databricks SQL Driver for Node.js with OAuth M2M authentication, you must do the following:

  1. Create a Databricks service principal in your Databricks workspace, and create an OAuth secret for that service principal.

    To create the service principal and its OAuth secret, see OAuth machine-to-machine (M2M) authentication. Make a note of the service principal’s UUID or Application ID value, and the Secret value for the service principal’s OAuth secret.

  2. Give the service principal access to your cluster or warehouse. See Cluster permissions or SQL warehouse access control.

To authenticate the Databricks SQL Driver for Node.js, use the following code snippet. This snippet assumes that you have set the following environment variables:

  • DATABRICKS_SERVER_HOSTNAMEset to the Server Hostname value for your cluster or SQL warehouse.

  • DATABRICKS_HTTP_PATH, set to HTTP Path value for your cluster or SQL warehouse.

  • DATABRICKS_CLIENT_ID, set to the service principal’s UUID or Application ID value.

  • DATABRICKS_CLIENT_SECRET, set to the Secret value for the service principal’s OAuth secret.

To set environment variables, see your operating system’s documentation.

const { DBSQLClient } = require('@databricks/sql');

const serverHostname = process.env.DATABRICKS_SERVER_HOSTNAME;
const httpPath       = process.env.DATABRICKS_HTTP_PATH;
const clientId       = process.env.DATABRICKS_CLIENT_ID;
const clientSecret   = process.env.DATABRICKS_CLIENT_SECRET;

if (!serverHostname || !httpPath || !clientId || !clientSecret) {
    throw new Error("Cannot find Server Hostname, HTTP Path, or " +
                    "service principal ID or secret. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME, " +
                    "DATABRICKS_HTTP_PATH, DATABRICKS_CLIENT_ID, and " +
                    "DATABRICKS_CLIENT_SECRET.");
  }

  const client = new DBSQLClient();
  const connectOptions = {
    authType:          "databricks-oauth",
    host:              serverHostname,
    path:              httpPath,
    oauthClientId:     clientId,
    oauthClientSecret: clientSecret
  };

  client.connect(connectOptions)
  // ...
import { DBSQLClient } from "@databricks/sql";

const serverHostname: string = process.env.DATABRICKS_SERVER_HOSTNAME || '';
const httpPath: string       = process.env.DATABRICKS_HTTP_PATH || '';
const clientId: string       = process.env.DATABRICKS_CLIENT_ID || '';
const clientSecret: string   = process.env.DATABRICKS_CLIENT_SECRET || '';

if (serverHostname == '' || httpPath == '' || clientId == '' || clientSecret == '') {
    throw new Error("Cannot find Server Hostname, HTTP Path, or " +
                    "service principal ID or secret. " +
                    "Check the environment variables DATABRICKS_SERVER_HOSTNAME, " +
                    "DATABRICKS_HTTP_PATH, DATABRICKS_CLIENT_ID, and " +
                    "DATABRICKS_CLIENT_SECRET.");
  }

  const client: DBSQLClient = new DBSQLClient();
  const connectOptions = {
    authType:          "databricks-oauth",
    host:              serverHostname,
    path:              httpPath,
    oauthClientId:     clientId,
    oauthClientSecret: clientSecret
  };

  client.connect(connectOptions)
  // ...

Query data

The following code example demonstrates how to call the Databricks SQL Driver for Node.js to run a basic SQL query on a Databricks compute resource. This command returns the first two rows from the trips table in the samples catalog’s nyctaxi schema.

This code example retrieves the token, server_hostname and http_path connection variable values from a set of Databricks environment variables. These environment variables have the following environment variable names:

  • DATABRICKS_TOKEN, which represents your Databricks personal access token from the requirements.

  • DATABRICKS_SERVER_HOSTNAME, which represents the Server Hostname value from the requirements.

  • DATABRICKS_HTTP_PATH, which represents the HTTP Path value from the requirements.

You can use other approaches to retrieving these connection variable values. Using environment variables is just one approach among many.

The following code example demonstrates how to call the Databricks SQL Connector for Node.js to run a basic SQL command on a cluster or SQL warehouse. This command returns the first two rows from the trips table.

const { DBSQLClient } = require('@databricks/sql');

const token          = process.env.DATABRICKS_TOKEN;
const serverHostname = process.env.DATABRICKS_SERVER_HOSTNAME;
const httpPath       = process.env.DATABRICKS_HTTP_PATH;

if (!token || !serverHostname || !httpPath) {
  throw new Error("Cannot find Server Hostname, HTTP Path, or personal access token. " +
                  "Check the environment variables DATABRICKS_TOKEN, " +
                  "DATABRICKS_SERVER_HOSTNAME, and DATABRICKS_HTTP_PATH.");
}

const client = new DBSQLClient();
const connectOptions = {
  token: token,
  host: serverHostname,
  path: httpPath
};

client.connect(connectOptions)
  .then(async client => {
    const session = await client.openSession();
    const queryOperation = await session.executeStatement(
      'SELECT * FROM samples.nyctaxi.trips LIMIT 2',
      {
        runAsync: true,
        maxRows:  10000 // This option enables the direct results feature.
      }
    );

    const result = await queryOperation.fetchAll();

    await queryOperation.close();

    console.table(result);

    await session.close();
    await client.close();
})
.catch((error) => {
  console.log(error);
});
import { DBSQLClient } from '@databricks/sql';
import IDBSQLSession from '@databricks/sql/dist/contracts/IDBSQLSession';
import IOperation from '@databricks/sql/dist/contracts/IOperation';

const serverHostname: string = process.env.DATABRICKS_SERVER_HOSTNAME || '';
const httpPath: string       = process.env.DATABRICKS_HTTP_PATH || '';
const token: string          = process.env.DATABRICKS_TOKEN || '';

if (serverHostname == '' || httpPath == '' || token == '') {
  throw new Error("Cannot find Server Hostname, HTTP Path, or personal access token. " +
                  "Check the environment variables DATABRICKS_SERVER_HOSTNAME, " +
                  "DATABRICKS_HTTP_PATH, and DATABRICKS_TOKEN.");
}

const client: DBSQLClient = new DBSQLClient();
const connectOptions = {
  host: serverHostname,
  path: httpPath,
  token: token
};

client.connect(connectOptions)
  .then(async client => {
    const session: IDBSQLSession = await client.openSession();

    const queryOperation: IOperation = await session.executeStatement(
      'SELECT * FROM samples.nyctaxi.trips LIMIT 2',
      {
        runAsync: true,
        maxRows: 10000 // This option enables the direct results feature.
      }
    );

    const result = await queryOperation.fetchAll();

    await queryOperation.close();

    console.table(result);

    await session.close();
    client.close();
  })
  .catch((error) => {
    console.log(error);
});

Output:

┌─────────┬─────┬────────┬───────────┬───────┬─────────┬────────┬───────┬───────┬────────┬────────┬────────┐
│ (index) │ _c0 │ carat  │    cut    │ color │ clarity │ depth  │ table │ price │   x    │   y    │   z    │
├─────────┼─────┼────────┼───────────┼───────┼─────────┼────────┼───────┼───────┼────────┼────────┼────────┤
│    0    │ '1' │ '0.23' │  'Ideal'  │  'E'  │  'SI2'  │ '61.5' │ '55'  │ '326' │ '3.95' │ '3.98' │ '2.43' │
│    1    │ '2' │ '0.21' │ 'Premium' │  'E'  │  'SI1'  │ '59.8' │ '61'  │ '326' │ '3.89' │ '3.84' │ '2.31' │
└─────────┴─────┴────────┴───────────┴───────┴─────────┴────────┴───────┴───────┴────────┴────────┴────────┘

Sessions

All IDBSQLSession methods that return IOperation objects in the API Reference have the following common parameters that affect their behavior:

  • Setting runAsync to true starts asynchronous mode. IDBSQLSession methods put operations into the queue and return as quickly as possible. The current state of the returned IOperation object might vary, and the client is responsible for checking its status before using the returned IOperation. See Operations. Setting runAsync to false means that IDBSQLSession methods wait for operations to complete. Databricks recommends always setting runAsync to true.

  • Setting maxRows to a non-null value enables direct results. With direct results, the server tries to wait for operations to complete and then fetches a portion of the data. Depending on how much work the server was able to complete within the defined time, IOperation objects return in some intermediate state instead of in some pending state. Very often all the metadata and query results are returned within a single request to the server. The server uses maxRows to determine how many records it can return immediately. However, the actual chunk may be of a different size; see IDBSQLSession.fetchChunk. Direct results are enabled by default. Databricks recommends against disabling direct results.

Operations

As described in Sessions, IOperation objects that are returned by IDBSQLSession session methods in the API Reference are not fully populated. The related server operation might still be in progress, such as waiting for the Databricks SQL warehouse to start, running the query, or fetching the data. The IOperation class hides these details from users. For example, methods such fetchAll, fetchChunk, and getSchema wait internally for operations to complete and then return results. You can use the IOperation.finished() method to explicitly wait for operations to complete. These methods take a callback that is periodically called while waiting for operations to complete. Setting the progress option to true attempts to request extra progress data from the server and pass it to that callback.

The close and cancel methods can be called at any time. When called, they immediately invalidate the IOperation object; all pending calls such as fetchAll, fetchChunk, and getSchema are immediately canceled and an error is returned. In some cases, the server operation might have already completed and the cancel method affects only the client.

The fetchAll method calls fetchChunk internally and collects all of the data into an array. While this is convenient, it might cause out of memory errors when used on large datasets. fetchAll options are typically passed to fetchChunk.

Fetch chunks of data

Fetching data chunks uses the following code pattern:

do {
  const chunk = await operation.fetchChunk();
  // Process the data chunk.
} while (await operation.hasMoreRows());

The fetchChunk method in the API Reference processes data in small portions to reduce memory consumption. fetchChunk first waits for operations to complete if they have not already completed, then calls a callback during the wait cycle, and then fetches the next data chunk.

You can use the maxRows option to specify the desired chunk size. However, the returned chunk might have a different size, smaller or even sometimes larger. fetchChunk does not attempt to prefetch data internally, in order to slice it into the requested portions. It sends the maxRows option to then server and returns whatever the server returns. Do not confuse this maxRows option with the one in IDBSQLSession. maxRows passed to fetchChunk defines the size of each chunk and does not do anything else.

Configure logging

The logger provides information for debugging problems with the connector. All DBSQLClient objects are instantiated with a logger that prints to the console, but by passing in a custom logger, you can send this information to a file. The following example shows how to configure a logger and change its level.

const { DBSQLLogger, LogLevel } = require('@databricks/sql');
const logger = new DBSQLLogger({
  filepath: 'log.txt',
  level: LogLevel.info
});

// Set logger to different level.
logger.setLevel(LogLevel.debug);
import { DBSQLLogger, LogLevel } from '@databricks/sql';
const logger = new DBSQLLogger({
  filepath: 'log.txt',
  level: LogLevel.info,
});

// Set logger to different level.
logger.setLevel(LogLevel.debug);

For additional examples, see the examples folder in the databricks/databricks-sql-nodejs repository on GitHub.

Additional resources

API reference

Classes

DBSQLClient class

Main entry point for interacting with a database.

Methods
connect method

Opens a connection to the database.

Parameters

options

Type: ConnectionOptions

The set of options used to connect to the database.

The host, path, and other required fields must be populated. See Authentication.

Example:

const client: DBSQLClient = new DBSQLClient();

client.connect(
  {
    host:  serverHostname,
    path:  httpPath,
    // ...
  }
)

Returns: Promise<IDBSQLClient>

openSession method

Opens session between DBSQLClient and database.

Parameters

request

Type: OpenSessionRequest

A set of optional parameters for specifying initial schema and initial catalog

Example:

const session = await client.openSession(
  {initialCatalog: 'catalog'}
);

Returns: Promise<IDBSQLSession>

getClient method

Returns internal thrift TCLIService.Client object. Must be called after DBSQLClient has connected.

No parameters

Returns TCLIService.Client

close method

Closes the connection to the database and releases all associated resources on the server. Any additional calls to this client will throw error.

No parameters.

No return value.

DBSQLSession class

DBSQLSessions are primarily used for the execution of statements against the databbase as well as various metadata fetching operations.

Methods
executeStatement method

Executes a statement with the options provided.

Parameters

statement

Type: str

The statement to be executed.

options

Type: ExecuteStatementOptions

A set of optional parameters for determining query timeout, max rows for direct results, and whether to run the query asynchronously. By default maxRows is set to 10000. If maxRows is set to null, the operation will run with the direct results feature off.

Example:

const session = await client.openSession(
  {initialCatalog: 'catalog'}
);

queryOperation = await session.executeStatement(
  'SELECT "Hello, World!"', { runAsync: true }
);

Returns: Promise<IOperation>

close method

Closes the session. Must be done after using session.

No parameters.

No return value.

getId method

Returns the GUID of the session.

No parameters.

Returns: str

getTypeInfo method

Returns information about supported data types.

Parameters

request

Type: TypeInfoRequest

Request parameters.

Returns: Promise<IOperation>

getCatalogs method

Gets list of catalogs.

Parameters

request

Type: CatalogsRequest

Request parameters.

Returns: Promise<IOperation>

getSchemas method

Gets list of schemas.

Parameters

request

Type: SchemasRequest

Request parameters. Fields catalogName and schemaName can be used for filtering purposes.

Returns: Promise<IOperation>

getTables method

Gets list of tables.

Parameters

request

Type: TablesRequest

Request parameters. Fields catalogName and schemaName and tableName can be used for filtering.

Returns: Promise<IOperation>

getFunctions method

Gets list of tables.

Parameters

request

Type: FunctionsRequest

Request parameters. Field functionName is required.

Returns: Promise<IOperation>

getPrimaryKeys method

Gets list of primary keys.

Parameters

request

Type: PrimaryKeysRequest

Request parameters. Fields schemaName and tableName are required.

Returns: Promise<IOperation>

getCrossReference method

Gets information about foreign keys between two tables.

Parameters

request

Type: CrossReferenceRequest

Request parameters. Schema, Parent, and Catalog name must be specified for both tables.

Returns: Promise<IOperation>

DBSQLOperation class

DBSQLOperations are created by DBSQLSessions and can be used to fetch the results of statements and check up on their execution. Data is fetched through functions fetchChunk and fetchAll.

Methods
getId method

Returns the GUID of the operation.

No parameters.

Returns: str

fetchAll method

Waits for operation completion, then fetches all rows from operation.

Parameters: None

Returns: Promise<Array<object>>

fetchChunk method

Waits for operation completion, then fetches up to a specified number of rows from an operation.

Parameters

options

Type: FetchOptions

Options used to fetch. Currently, the only option is maxRows, which corresponds to the max number of data objects to be returned in any given array.

Returns: Promise<Array<object>>

close method

Closes the operation and releases all associated resources. Must be done after no longer using operation.

No parameters.

No return value.