Build a PostgreSQL Interface for Google Data Catalog 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 Google Data Catalog data as a PostgreSQL database, use the CData JDBC Driver for Google Data Catalog and a JDBC foreign data wrapper (FDW). In this article, we compile the FDW, install it, and query Google Data Catalog data from PostgreSQL Server.

Connect to Google Data Catalog Data as a JDBC Data Source

To connect to Google Data Catalog 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.googledatacatalog.GoogleDataCatalogDriver
  

• JDBC URL: The URL must start with "jdbc:googledatacatalog:" and can include any of the connection properties in name-value pairs separated with semicolons.

  Google Data Catalog uses the OAuth authentication standard. Authorize access to Google APIs on behalf on individual users or on behalf of users in a domain.

  Before connecting, specify the following to identify the organization and project you would like to connect to:

  • OrganizationId: The ID associated with the Google Cloud Platform organization resource you would like to connect to. Find this by navigating to the cloud console.

    Click the project selection drop-down, and select your organization from the list. Then, click More -> Settings. The organization ID is displayed on this page.

  • ProjectId: The ID associated with the Google Cloud Platform project resource you would like to connect to.

    Find this by navigating to the cloud console dashboard and selecting your project from the Select from drop-down. The project ID will be present in the Project info card.

  When you connect, the OAuth endpoint opens in your default browser. Log in and grant permissions to the application to completes the OAuth process. For more information, refer to the OAuth section in the Help documentation.

  Built-in Connection String Designer

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

  java -jar cdata.jdbc.googledatacatalog.jar
  

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

  👁 Using the built-in connection string designer to generate a JDBC URL (Salesforce is shown.)
  

  A typical JDBC URL is below:

  jdbc:googledatacatalog:ProjectId=YourProjectId;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 Google Data Catalog Data as a PostgreSQL Database

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

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

   CREATE EXTENSION jdbc2_fdw;
   

3. Create a server object for Google Data Catalog:

   CREATE SERVER GoogleDataCatalog 
   FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS (
   drivername 'cdata.jdbc.googledatacatalog.GoogleDataCatalogDriver',
   url 'jdbc:googledatacatalog:ProjectId=YourProjectId;InitiateOAuth=GETANDREFRESH;',
   querytimeout '15',
   jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.googledatacatalog.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 GoogleDataCatalog OPTIONS (
   username 'admin', 
   password 'test');
   

5. Create a foreign table in your local database:

   postgres=# CREATE FOREIGN TABLE schemas (
   schemas_id text,
   schemas_Type text,
   schemas_DatasetName numeric) 
   SERVER GoogleDataCatalog OPTIONS (
   table_name 'schemas');
   

You can now execute SELECT commands to Google Data Catalog:

postgres=# SELECT * FROM schemas;