Build a PostgreSQL Interface for Lakebase Data using the CData JDBC Driver

There are a vast number of PostgreSQL clients available on the Internet. From standard Drivers to BI and Analytics tools, PostgreSQL is a popular interface for data access. Using our JDBC Drivers, you can now create PostgreSQL entry-points that you can connect to from any standard client.

To access Lakebase data as a PostgreSQL database, use the CData JDBC Driver for Lakebase and a JDBC foreign data wrapper (FDW). In this article, we compile the FDW, install it, and query Lakebase data from PostgreSQL Server.

Connect to Lakebase Data as a JDBC Data Source

To connect to Lakebase as a JDBC data source, you will need the following:

• Driver JAR path: The JAR is located in the lib subfolder of the installation directory.

• Driver class:

  cdata.jdbc.lakebase.LakebaseDriver
  

• JDBC URL: The URL must start with "jdbc:lakebase:" and can include any of the connection properties in name-value pairs separated with semicolons. To connect to Databricks Lakebase, start by setting the following properties:
  • DatabricksInstance: The Databricks instance or server hostname, provided in the format instance-abcdef12-3456-7890-abcd-abcdef123456.database.cloud.databricks.com.
  • Server: The host name or IP address of the server hosting the Lakebase database.
  • Port (optional): The port of the server hosting the Lakebase database, set to 5432 by default.
  • Database (optional): The database to connect to after authenticating to the Lakebase Server, set to the authenticating user's default database by default.

  OAuth Client Authentication

  To authenicate using OAuth client credentials, you need to configure an OAuth client in your service principal. In short, you need to do the following:

  1. Create and configure a new service principal
  2. Assign permissions to the service principal
  3. Create an OAuth secret for the service principal

  For more information, refer to the Setting Up OAuthClient Authentication section in the Help documentation.

  OAuth PKCE Authentication

  To authenticate using the OAuth code type with PKCE (Proof Key for Code Exchange), set the following properties:

  • AuthScheme: OAuthPKCE.
  • User: The authenticating user's user ID.

  For more information, refer to the Help documentation.

  Built-in Connection String Designer

  For assistance in constructing the JDBC URL, use the connection string designer built into the Lakebase JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

  java -jar cdata.jdbc.lakebase.jar
  

  Fill in the connection properties and copy the connection string to the clipboard.

  

  A typical JDBC URL is below:

  jdbc:lakebase:DatabricksInstance=lakebase;Server=127.0.0.1;Port=5432;Database=my_database;InitiateOAuth=GETANDREFRESH;
  

Build the JDBC Foreign Data Wrapper

The Foreign Data Wrapper can be installed as an extension to PostgreSQL, without recompiling PostgreSQL. The jdbc2_fdw extension is used as an example (downloadable here).

1. Add a symlink from the shared object for your version of the JRE to /usr/lib/libjvm.so. For example:

   ln -s /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server/libjvm.so /usr/lib/libjvm.so
   

2. Start the build:

   make install USE_PGXS=1
   

Query Lakebase Data as a PostgreSQL Database

After you have installed the extension, follow the steps below to start executing queries to Lakebase data:

1. Log into your database.
2. Load the extension for the database:

   CREATE EXTENSION jdbc2_fdw;
   

3. Create a server object for Lakebase:

   CREATE SERVER Lakebase 
   FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS (
   drivername 'cdata.jdbc.lakebase.LakebaseDriver',
   url 'jdbc:lakebase:DatabricksInstance=lakebase;Server=127.0.0.1;Port=5432;Database=my_database;InitiateOAuth=GETANDREFRESH;',
   querytimeout '15',
   jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.lakebase.jar'); 
   

4. Create a user mapping for the username and password of a user known to the MySQL daemon.

   CREATE USER MAPPING for postgres SERVER Lakebase OPTIONS (
   username 'admin', 
   password 'test');
   

5. Create a foreign table in your local database:

   postgres=# CREATE FOREIGN TABLE orders (
   orders_id text,
   orders_ShipName text,
   orders_ShipCity numeric) 
   SERVER Lakebase OPTIONS (
   table_name 'orders');
   

postgres=# SELECT * FROM orders;