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============================
Arrow Flight SQL JDBC Driver
============================

The Flight SQL JDBC driver is a JDBC driver implementation that uses
the :external+arrow:doc:`Flight SQL protocol <format/FlightSql>` under
the hood.  This driver can be used with any database that implements
Flight SQL.

Installation and Requirements
=============================

The driver is compatible with JDK 17+. Note that the following JVM
parameter is required:

.. code-block:: shell

   java --add-opens=java.base/java.nio=ALL-UNNAMED ...

To add a dependency via Maven, use a ``pom.xml`` like the following:

.. code-block:: xml

   <?xml version="1.0" encoding="UTF-8"?>
   <project xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>org.example</groupId>
     <artifactId>demo</artifactId>
     <version>1.0-SNAPSHOT</version>
     <properties>
       <arrow.version>18.1.0</arrow.version>
     </properties>
     <dependencies>
       <dependency>
         <groupId>org.apache.arrow</groupId>
         <artifactId>flight-sql-jdbc-driver</artifactId>
         <version>${arrow.version}</version>
       </dependency>
     </dependencies>
   </project>

Connecting to a Database
========================

The URI format is as follows::

  jdbc:arrow-flight-sql://HOSTNAME:PORT[/?param1=val1&param2=val2&...]

For example, take this URI::

  jdbc:arrow-flight-sql://localhost:12345/?username=admin&password=pass&useEncryption=1

This will connect to a Flight SQL service running on ``localhost`` on
port 12345.  It will create a secure, encrypted connection, and
authenticate using the username ``admin`` and the password ``pass``.

The components of the URI are as follows.

* The URI scheme must be ``jdbc:arrow-flight-sql://``.
* **HOSTNAME** is the hostname of the Flight SQL service.
* **PORT** is the port of the Flight SQL service.

Additional options can be passed as query parameters. Parameter names are
case-sensitive. The supported parameters are:

.. list-table::
   :header-rows: 1

   * - Parameter
     - Default
     - Description

   * - disableCertificateVerification
     - false
     - When TLS is enabled, whether to verify the server certificate

   * - password
     - null
     - The password for user/password authentication

   * - threadPoolSize
     - 1
     - The size of an internal thread pool

   * - token
     - null
     - The token used for token authentication

   * - trustStore
     - null
     - When TLS is enabled, the path to the certificate store

   * - trustStorePassword
     - null
     - When TLS is enabled, the password for the certificate store

   * - tlsRootCerts
     - null
     - Path to PEM-encoded root certificates for TLS - use this as
       an alternative to ``trustStore``

   * - clientCertificate
     - null
     - Path to PEM-encoded client mTLS certificate when the Flight
       SQL server requires client verification.

   * - clientKey
     - null
     - Path to PEM-encoded client mTLS key when the Flight
       SQL server requires client verification.

   * - useEncryption
     - true
     - Whether to use TLS (the default is an encrypted connection)

   * - user
     - null
     - The username for user/password authentication

   * - useSystemTrustStore
     - true
     - When TLS is enabled, whether to use the system certificate store

   * - retainCookies
     - true
     - Whether to use cookies from the initial connection in subsequent
       internal connections when retrieving streams from separate endpoints.

   * - retainAuth
     - true
     - Whether to use bearer tokens obtained from the initial connection
       in subsequent internal connections used for retrieving streams
       from separate endpoints.

Note that URI values must be URI-encoded if they contain characters such
as !, @, $, etc.

Any URI parameters that are not handled by the driver are passed to
the Flight SQL service as gRPC headers. For example, the following URI ::

  jdbc:arrow-flight-sql://localhost:12345/?useEncryption=0&database=mydb

This will connect without authentication or encryption, to a Flight
SQL service running on ``localhost`` on port 12345. Each request will
also include a ``database=mydb`` gRPC header.

Connection parameters may also be supplied using the Properties object
when using the JDBC Driver Manager to connect. When supplying using
the Properties object, values should *not* be URI-encoded.

Parameters specified by the URI supercede parameters supplied by the
Properties object. When calling the `user/password overload of
DriverManager#getConnection()
<https://docs.oracle.com/javase/8/docs/api/java/sql/DriverManager.html#getConnection-java.lang.String-java.lang.String-java.lang.String->`_,
the username and password supplied on the URI supercede the username and
password arguments to the function call.

OAuth 2.0 Authentication
========================

The driver supports OAuth 2.0 authentication for obtaining access tokens
from an authorization server. Two OAuth flows are currently supported:

* **Client Credentials** - For service-to-service authentication where no
  user interaction is required. The application authenticates using its own
  credentials (client ID and client secret).

* **Token Exchange** (RFC 8693) - For exchanging one token for another,
  commonly used for federated authentication, delegation, or impersonation
  scenarios.

OAuth Connection Properties
---------------------------

The following properties configure OAuth authentication. These properties
should be provided via the ``Properties`` object when connecting, as they
may contain special characters that are difficult to encode in a URI.

**Common OAuth Properties**

.. list-table::
   :header-rows: 1

   * - Parameter
     - Type
     - Required
     - Default
     - Description

   * - oauth.flow
     - String
     - Yes (to enable OAuth)
     - null
     - The OAuth grant type. Supported values: ``client_credentials``,
       ``token_exchange``

   * - oauth.tokenUri
     - String
     - Yes
     - null
     - The OAuth 2.0 token endpoint URL (e.g.,
       ``https://auth.example.com/oauth/token``)

   * - oauth.clientId
     - String
     - Conditional
     - null
     - The OAuth 2.0 client ID. Required for ``client_credentials`` flow,
       optional for ``token_exchange``

   * - oauth.clientSecret
     - String
     - Conditional
     - null
     - The OAuth 2.0 client secret. Required for ``client_credentials`` flow,
       optional for ``token_exchange``

   * - oauth.scope
     - String
     - No
     - null
     - Space-separated list of OAuth scopes to request

   * - oauth.resource
     - String
     - No
     - null
     - The resource indicator for the token request (RFC 8707)

**Token Exchange Properties**

These properties are specific to the ``token_exchange`` flow:

.. list-table::
   :header-rows: 1

   * - Parameter
     - Type
     - Required
     - Default
     - Description

   * - oauth.exchange.subjectToken
     - String
     - Yes
     - null
     - The subject token to exchange (e.g., a JWT from an identity provider)

   * - oauth.exchange.subjectTokenType
     - String
     - Yes
     - null
     - The token type URI of the subject token. Common values:
       ``urn:ietf:params:oauth:token-type:access_token``,
       ``urn:ietf:params:oauth:token-type:jwt``

   * - oauth.exchange.actorToken
     - String
     - No
     - null
     - The actor token for delegation/impersonation scenarios

   * - oauth.exchange.actorTokenType
     - String
     - No
     - null
     - The token type URI of the actor token

   * - oauth.exchange.aud
     - String
     - No
     - null
     - The target audience for the exchanged token

   * - oauth.exchange.requestedTokenType
     - String
     - No
     - null
     - The desired token type for the exchanged token