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

Connect to Google Cloud Storage Data as a JDBC Data Source

To connect to Google Cloud Storage 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.googlecloudstorage.GoogleCloudStorageDriver
  

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

  Authenticate with a User Account

  You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

  When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

  Authenticate with a Service Account

  Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

  You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

  • InitiateOAuth: Set this to GETANDREFRESH.
  • OAuthJWTCertType: Set this to "PFXFILE".
  • OAuthJWTCert: Set this to the path to the .p12 file you generated.
  • OAuthJWTCertPassword: Set this to the password of the .p12 file.
  • OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
  • OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
  • OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
  • ProjectId: Set this to the Id of the project you want to connect to.

  The OAuth flow for a service account then completes.

  Built-in Connection String Designer

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

  java -jar cdata.jdbc.googlecloudstorage.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:googlecloudstorage:ProjectId='project1';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 Cloud Storage Data as a PostgreSQL Database

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

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

   CREATE EXTENSION jdbc2_fdw;
   

3. Create a server object for Google Cloud Storage:

   CREATE SERVER GoogleCloudStorage 
   FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS (
   drivername 'cdata.jdbc.googlecloudstorage.GoogleCloudStorageDriver',
   url 'jdbc:googlecloudstorage:ProjectId='project1';InitiateOAuth=GETANDREFRESH;',
   querytimeout '15',
   jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.googlecloudstorage.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 GoogleCloudStorage OPTIONS (
   username 'admin', 
   password 'test');
   

5. Create a foreign table in your local database:

   postgres=# CREATE FOREIGN TABLE buckets (
   buckets_id text,
   buckets_Name text,
   buckets_OwnerId numeric) 
   SERVER GoogleCloudStorage OPTIONS (
   table_name 'buckets');
   

You can now execute SELECT commands to Google Cloud Storage:

postgres=# SELECT * FROM buckets;