Skip to main content

Create a JDBC source connector from PostgreSQL® to Apache Kafka®

The JDBC source connector pushes data from a relational database, such as PostgreSQL®, to Apache Kafka® where can be transformed and read by multiple consumers.

tip

Sourcing data from a database into Apache Kafka decouples the database from the set of consumers. Once the data is in Apache Kafka, multiple applications can access it without adding any additional query overhead to the source database.

note

See the full set of available parameters and configuration options in the connector's documentation.

Prerequisites​

To setup a JDBC source connector pointing to PostgreSQL, you need an Aiven for Apache Kafka service with Kafka Connect enabled or a dedicated Aiven for Apache Kafka Connect cluster.

Also collect the following information about the source PostgreSQL database upfront:

  • PG_HOST: The database hostname
  • PG_PORT: The database port
  • PG_USER: The database user to connect
  • PG_PASSWORD: The database password for the PG_USER
  • PG_DATABASE_NAME: The database name
  • SSL_MODE: The SSL mode
  • PG_TABLES: The list of database tables to be included in Apache Kafka; the list must be in the form of schema_name1.table_name1,schema_name2.table_name2
note

If you're using Aiven for PostgreSQL the above details are available in the Aiven console service Overview tab or via the dedicated avn service get command with the Aiven CLI.

Setup a PostgreSQL JDBC source connector with Aiven CLI​

The following example demonstrates how to setup an Apache Kafka JDBC source connector to a PostgreSQL database using the Aiven CLI dedicated command.

Define a Kafka Connect configuration file​

Define the connector configurations in a file (we'll refer to it with the name jdbc_source_pg.json) with the following content:

{
    "name":"CONNECTOR_NAME",
    "connector.class":"io.aiven.connect.jdbc.JdbcSourceConnector",
    "connection.url":"jdbc:postgresql://PG_HOST:PG_PORT/PG_DATABASE_NAME?sslmode=SSL_MODE",
    "connection.user":"PG_USER",
    "connection.password":"PG_PASSWORD",
    "table.whitelist":"PG_TABLES",
    "mode":"JDBC_MODE",
    "topic.prefix":"KAFKA_TOPIC_PREFIX",
    "tasks.max":"NR_TASKS",
    "poll.interval.ms":"POLL_INTERVAL"
}

The configuration file contains the following entries:

  • name: the connector name
  • PG_HOST, PG_PORT, PG_DATABASE_NAME, SSL_MODE, PG_USER, PG_PASSWORD and PG_TABLES: source database parameters collected in the prerequisite phase.
  • mode: the query mode, more information in the dedicated page; depending on the selected mode, additional configuration entries might be required.
  • topic.prefix: the prefix that will be used for topic names. The resulting topic name will be the concatenation of the topic.prefix and the table name.
  • tasks.max: maximum number of tasks to execute in parallel. By default is 1, the connector can use at max 1 task for each source table defined.
  • poll.interval.ms: query frequency, default 5000 milliseconds

See the dedicated documentation for the full list of parameters.

tip

Check the dedicated blog post for an end-to-end example of the JDBC source connector in action with PostgreSQL®.

Create a Kafka Connect connector with Aiven CLI​

To create the connector, execute the following Aiven CLI command, replacing the SERVICE_NAME with the name of the Aiven service where the connector needs to run:

avn service connector create SERVICE_NAME @jdbc_source_pg.json

Check the connector status with the following command, replacing the SERVICE_NAME with the Aiven service and the CONNECTOR_NAME with the name of the connector defined before:

avn service connector status SERVICE_NAME CONNECTOR_NAME

Verify in the Apache Kafka target instance, the presence of the topic and the data

tip

If you're using Aiven for Apache Kafka, topics will not be created automatically. Either create them manually following the topic.prefix.schema_name.table_name naming pattern or enable the kafka.auto_create_topics_enable advanced parameter.

Example: define a JDBC incremental connector​

The example creates an incremental JDBC connector with the following properties:

  • connector name: jdbc_source_pg_increment
  • source tables: students and exams from the public schema, available in an Aiven for PostgreSQL database
  • incremental column name: id
  • topic prefix: jdbc_source_pg_increment.
  • maximum number of concurrent tasks: 1
  • time interval between queries: 5 seconds

The connector configuration is the following:

{
    "name":"jdbc_source_pg_increment",
    "connector.class":"io.aiven.connect.jdbc.JdbcSourceConnector",
    "connection.url":"jdbc:postgresql://demo-pg-myproject.aivencloud.com:13039/defaultdb?sslmode=require",
    "connection.user":"avnadmin",
    "connection.password":"mypassword123",
    "table.whitelist":"public.students,public.exams",
    "mode":"incrementing",
    "incrementing.column.name":"id",
    "topic.prefix":"jdbc_source_pg_increment.",
    "tasks.max":"1",
    "poll.interval.ms":"5000"
}

With the above configuration stored in a jdbc_incremental_source_pg.json file, you can create the connector in the demo-kafka instance with:

avn service connector create demo-kafka @jdbc_incremental_source_pg.json