A PostgreSQL Interface for Kafka Data

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

Connect to Kafka Data as a JDBC Data Source

To connect to Kafka 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.apachekafka.ApacheKafkaDriver

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

  Set BootstrapServers and the Topic properties to specify the address of your Apache Kafka server, as well as the topic you would like to interact with.

  Authorization Mechanisms

  • SASL Plain: The User and Password properties should be specified. AuthScheme should be set to 'Plain'.
  • SASL SSL: The User and Password properties should be specified. AuthScheme should be set to 'Scram'. UseSSL should be set to true.
  • SSL: The SSLCert and SSLCertPassword properties should be specified. UseSSL should be set to true.
  • Kerberos: The User and Password properties should be specified. AuthScheme should be set to 'Kerberos'.

  You may be required to trust the server certificate. In such cases, specify the TrustStorePath and the TrustStorePassword if necessary.

  Built-in Connection String Designer

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

  java -jar cdata.jdbc.apachekafka.jar

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

  A typical JDBC URL is below:

  jdbc:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;

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 Kafka Data as a PostgreSQL Database

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

1. Log into your database.
2. Load the extension for the database: CREATE EXTENSION jdbc2_fdw;
3. Create a server object for Kafka: CREATE SERVER ApacheKafka FOREIGN DATA WRAPPER jdbc2_fdw OPTIONS ( drivername 'cdata.jdbc.apachekafka.ApacheKafkaDriver', url 'jdbc:apachekafka:User=admin;Password=pass;BootStrapServers=https://localhost:9091;Topic=MyTopic;', querytimeout '15', jarfile '/home/MyUser/CData/CData\ JDBC\ Driver\ for\ Salesforce MyDriverEdition/lib/cdata.jdbc.apachekafka.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 ApacheKafka OPTIONS ( username 'admin', password 'test');
5. Create a foreign table in your local database: postgres=# CREATE FOREIGN TABLE sampletable_1 ( sampletable_1_id text, sampletable_1_Id text, sampletable_1_Column1 numeric) SERVER ApacheKafka OPTIONS ( table_name 'sampletable_1');