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A PostgreSQL Interface for Quandl Data

Use the Remoting features of the Quandl JDBC Driver to create a PostgreSQL entry-point for data access.

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

Connect to Quandl Data as a JDBC Data Source

To connect to Quandl 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.quandl.QuandlDriver

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

    Quandl uses an API key for authentication. See the help documentation for a guide to obtaining the APIKey property.

    Additionally, set the DatabaseCode connection property to the code identifying the Database whose Datasets you want to query with SQL. You can search the available Databases by querying the Databases view.

    Built-in Connection String Designer

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

    java -jar cdata.jdbc.quandl.jar

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

    A typical JDBC URL is below:

    jdbc:quandl:APIKey=abc123;DatabaseCode=WIKI;

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.

  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 Quandl Data as a PostgreSQL Database

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

  1. Log into your database.
  2. Load the extension for the database: CREATE EXTENSION jdbc2_fdw;
  3. Create a server object for Quandl: CREATE SERVER Quandl FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS ( drivername 'cdata.jdbc.quandl.QuandlDriver', url 'jdbc:quandl:APIKey=abc123;DatabaseCode=WIKI;', querytimeout '15', jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.quandl.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 Quandl OPTIONS ( username 'admin', password 'test');
  5. Create a foreign table in your local database: postgres=# CREATE FOREIGN TABLE aapl ( aapl_id text, aapl_Date text, aapl_Volume numeric) SERVER Quandl OPTIONS ( table_name 'aapl');
You can now execute read/write commands to Quandl: postgres=# SELECT * FROM aapl;