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

Connect to SQL Server Data as a JDBC Data Source

To connect to SQL Server 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.sql.SQLDriver
  

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

  Connecting to Microsoft SQL Server

  Connect to Microsoft SQL Server using the following properties:

  • Server: The name of the server running SQL Server.
  • User: The username provided for authentication with SQL Server.
  • Password: The password associated with the authenticating user.
  • Database: The name of the SQL Server database.

  Connecting to Azure SQL Server and Azure Data Warehouse

  You can authenticate to Azure SQL Server or Azure Data Warehouse by setting the following connection properties:

  • Server: The server running Azure. You can find this by logging into the Azure portal and navigating to "SQL databases" (or "SQL data warehouses") -> "Select your database" -> "Overview" -> "Server name."
  • User: The name of the user authenticating to Azure.
  • Password: The password associated with the authenticating user.
  • Database: The name of the database, as seen in the Azure portal on the SQL databases (or SQL warehouses) page.

  SSH Connectivity for SQL Server

  You can use SSH (Secure Shell) to authenticate with SQL Server, whether the instance is hosted on-premises or in supported cloud environments. SSH authentication ensures that access is encrypted (as compared to direct network connections).

  SSH Connections to SQL Server in Password Auth Mode

  To connect to SQL Server via SSH in Password Auth mode, set the following connection properties:

  • User: SQL Server User name
  • Password: SQL Server Password
  • Database: SQL Server database name
  • Server: SQL Server Server name
  • Port: SQL Server port number like 3306
  • UserSSH: "true"
  • SSHAuthMode: "Password"
  • SSHPort: SSH Port number
  • SSHServer: SSH Server name
  • SSHUser: SSH User name
  • SSHPassword: SSH Password

  SSH Connections to SQL Server in Public Key Auth Mode

  To connect to SQL Server via SSH in Password Auth mode, set the following connection properties:

  • User: SQL Server User name
  • Password: SQL Server Password
  • Database: SQL Server database name
  • Server: SQL Server Server name
  • Port: SQL Server port number like 3306
  • UserSSH: "true"
  • SSHAuthMode: "Public_Key"
  • SSHPort: SSH Port number
  • SSHServer: SSH Server name
  • SSHUser: SSH User name
  • SSHClientCret: the path for the public key certificate file

  Built-in Connection String Designer

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

  java -jar cdata.jdbc.sql.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:sql:User=myUser;Password=myPassword;Database=NorthWind;Server=myServer;Port=1433;
  

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 SQL Server Data as a PostgreSQL Database

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

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

   CREATE EXTENSION jdbc2_fdw;
   

3. Create a server object for SQL Server:

   CREATE SERVER SQL 
   FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS (
   drivername 'cdata.jdbc.sql.SQLDriver',
   url 'jdbc:sql:User=myUser;Password=myPassword;Database=NorthWind;Server=myServer;Port=1433;',
   querytimeout '15',
   jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.sql.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 SQL 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_Freight numeric) 
   SERVER SQL OPTIONS (
   table_name 'orders');
   

You can now execute read/write commands to SQL Server:

postgres=# SELECT * FROM orders;