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

Connect to Linear Data as a JDBC Data Source

To connect to Linear 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.linear.LinearDriver
  

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

  You can authenticate to Linear with a personal API key or with OAuth 2.0. The API key is the simplest option for connecting with your own Linear account.

  Authenticating with an API Key

  Set the following connection properties:

  • AuthScheme: Set this to APIKey.
  • APIKey: A Linear personal API key.

  To create a personal API key, log in to Linear, open Settings > Security & access > Personal API keys, select New API key, and create it. Copy the key immediately, because Linear shows it only once.

  Authenticating with OAuth

  OAuth requires a custom OAuth application registered in Linear (Settings > API > OAuth applications), which provides the OAuthClientId and OAuthClientSecret. Two flows are supported:

  • Authorization code: Set AuthScheme to OAuth, InitiateOAuth to GETANDREFRESH, and provide OAuthClientId, OAuthClientSecret, and the CallbackURL defined in your application (e.g., http://localhost:33333). The driver opens Linear in your browser so you can grant access.
  • Client credentials: Set AuthScheme to OAuthClient and provide OAuthClientId and OAuthClientSecret. This authenticates the application itself, with no browser interaction, and suits machine-to-machine integrations.

  By default, the driver requests the read,write scopes. The driver refreshes the access token automatically when it expires.

  Built-in Connection String Designer

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

  
  java -jar cdata.jdbc.linear.jar
  

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

  

  A typical JDBC URL is below:

  
  jdbc:linear:AuthScheme=APIKey;APIKey=myAPIKey;
  

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 Linear Data as a PostgreSQL Database

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

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

   
   CREATE EXTENSION jdbc2_fdw;
   

3. Create a server object for Linear:

   
   CREATE SERVER Linear 
   FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS (
   drivername 'cdata.jdbc.linear.LinearDriver',
   url 'jdbc:linear:AuthScheme=APIKey;APIKey=myAPIKey;',
   querytimeout '15',
   jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.linear.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 Linear OPTIONS (
   username 'admin', 
   password 'test');
   

5. Create a foreign table in your local database:

   
   postgres=# CREATE FOREIGN TABLE team (
   team_id text,
   team_id text,
   team_name numeric) 
   SERVER Linear OPTIONS (
   table_name 'team');
   

postgres=# SELECT * FROM team;