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Create a Debezium source connector from SQL Server to Apache Kafka® with CDC

The SQL Server Debezium source connector uses the change data capture (CDC) feature to extract database changes from designated tables and write them to Apache Kafka® topic in a standard format for multiple consumers to read and transform.


Breaking changes in Debezium 2.5

Debezium version 2.5 introduces significant changes to the connector's configuration and behavior. New setups defaults to version 2.5 while existing setups using version 1.9 remain on that version for stability. Test configurations with version 2.5 before upgrading. Review the specific changes to the MongoDB connector in Debezium 2.5. For help with upgrades or queries, contact Aiven support.

Enable CDC in SQL Server

To use the Debezium source connector for SQL Server, enable the SQL Server Change Data Capture (CDC) at both the database and table levels. This creates the necessary schemas and tables containing a history of all change events in the tables you wish to track with the connector.

Enable CDC at database level

To enable the CDC at database level, you can use the following command:

EXEC sys.sp_cdc_enable_db

If you're using GCP Cloud SQL for SQL Server, you can enable database CDC with:

EXEC msdb.dbo.gcloudsql_cdc_enable_db '<DATABASE_NAME>'

Enabling CDC creates a new schema called cdc in the target database, which contains all necessary tables.

Enable CDC at table level

To enable CDC for a table you can execute the following command:


EXEC sys.sp_cdc_enable_table
@source_schema = N'<SCHEMA_NAME>',
@source_name = N'<TABLE_NAME>',
@role_name = N'<ROLE_NAME>',
@filegroup_name = N'<FILEGROUP_NAME>',
@supports_net_changes = 0

The command above has the following parameters:

  • <DATABASE_NAME>, <SCHEMA_NAME>, <TABLE_NAME>: The references to the table where CDC needs to be set.
  • <ROLE_NAME>: The database role that will have access to the change tables. Leave it NULL to only allow access to members of sysadmin or db_owner groups.
  • <FILEGROUP_NAME>: Specifies the file group where the files will be written, needs to be pre-existing.

If you're using GCP Cloud SQL for SQL Server, you can enable database CDC on a table with:

EXEC sys.sp_cdc_enable_table
@source_schema = N'<SCHEMA_NAME>',
@source_name = N'<TABLE_NAME>',
@role_name = N'<ROLE_NAME>'

When modifying table schemas online, new column information can be lost until CDC is re-enabled for the table. For more details, refer to the related Debezium documentation.


To configure a Debezium source connector for MongoDB, you need either an Aiven for Apache Kafka service with Apache Kafka Connect enabled or a dedicated Aiven for Apache Kafka Connect cluster.

Before you begin, gather the necessary information about your source MongoDB database:

  • SQLSERVER_HOST: The database hostname
  • SQLSERVER_PORT: The database port
  • SQLSERVER_USER: The database user to connect
  • SQLSERVER_PASSWORD: The database password for the SQLSERVER_USER
  • SQLSERVER_DATABASE_NAME: The database name
  • SQLSERVER_TABLES: The list of database tables to be included in Apache Kafka. Format the list as schema_name1.table_name1,schema_name2.table_name2
  • APACHE_KAFKA_HOST: The hostname of the Apache Kafka service, needed when storing the schema definition changes
  • APACHE_KAFKA_PORT: The port of the Apache Kafka service, needed when storing the schema definition changes
  • SCHEMA_REGISTRY_PORT: The Apache Kafka's schema registry port, only needed when using Avro as data format
  • SCHEMA_REGISTRY_USER: The Apache Kafka's schema registry username, only needed when using Avro as data format
  • SCHEMA_REGISTRY_PASSWORD: The Apache Kafka's schema registry user password, only needed when using Avro as data format

If you are using Aiven for PostgreSQL and Aiven for Apache Kafka the above details are available in the Aiven console service Overview page or via the dedicated avn service get command with the Aiven CLI.

For a complete list of all available parameters and configuration options, see Debezium connector's documentation.

Setup a SQL Server Debezium source connector with Aiven Console

The following example demonstrates how to setup a Debezium source Connector for Apache Kafka to a SQL Server database using the Aiven Console.

Define a Kafka Connect configuration file

Create a configuration file named debezium_source_mysql.json with the following connector configurations. While optional, creating this file helps you organize your settings in one place and copy/paste them into the Aiven Console later.

"connector.class": "io.debezium.connector.sqlserver.SqlServerConnector",
"database.hostname": "SQLSERVER_HOST",
"database.port": "SQLSERVER_PORT",
"database.user": "SQLSERVER_USER",
"database.password": "SQLSERVER_PASSWORD",
"database.dbname": "SQLSERVER_DATABASE_NAME",
"table.include.list": "SQLSERVER_TABLES",
"": 500,
"key.converter": "io.confluent.connect.avro.AvroConverter",
"key.converter.schema.registry.url": "https://APACHE_KAFKA_HOST:SCHEMA_REGISTRY_PORT",
"key.converter.basic.auth.credentials.source": "USER_INFO",
"value.converter": "io.confluent.connect.avro.AvroConverter",
"value.converter.schema.registry.url": "https://APACHE_KAFKA_HOST:SCHEMA_REGISTRY_PORT",
"value.converter.basic.auth.credentials.source": "USER_INFO",
"database.history.kafka.topic": "HISTORY_TOPIC_NAME",
"database.history.kafka.bootstrap.servers": "APACHE_KAFKA_HOST:APACHE_KAFKA_PORT",
"": "SSL",
"database.history.producer.ssl.keystore.type": "PKCS12",
"database.history.producer.ssl.keystore.location": "/run/aiven/keys/public.keystore.p12",
"database.history.producer.ssl.keystore.password": "password",
"database.history.producer.ssl.truststore.location": "/run/aiven/keys/public.truststore.jks",
"database.history.producer.ssl.truststore.password": "password",
"database.history.producer.ssl.key.password": "password",
"": "SSL",
"database.history.consumer.ssl.keystore.type": "PKCS12",
"database.history.consumer.ssl.keystore.location": "/run/aiven/keys/public.keystore.p12",
"database.history.consumer.ssl.keystore.password": "password",
"database.history.consumer.ssl.truststore.location": "/run/aiven/keys/public.truststore.jks",
"database.history.consumer.ssl.truststore.password": "password",
"database.history.consumer.ssl.key.password": "password",
"include.schema.changes": "true"

The configuration file contains the following entries:

  • name: The connector name, replace CONNECTOR_NAME with the name you want to use for the connector.


  • The logical name of the database, which determines the prefix used for Apache Kafka topic names. The resulting topic name is a combination of the and the table name.

  • tasks.max: Maximum number of tasks to execute in parallel. By default this is 1, the connector can use at most 1 task for each source table defined. Replace NR_TASKS with the amount of parallel task based on the number of input tables.

  • The frequency of the queries to the CDC tables.

  • database.history.kafka.topic: The name of the Apache Kafka topic that contains the history of schema changes.

  • database.history.kafka.bootstrap.servers: Directs to the Aiven for Apache Kafka service where the connector is running and is needed to store schema definition changes

  • database.history.producer and database.history.consumer: Refers to truststores and keystores pre-created on the Aiven for Apache Kafka node to handle SSL authentication


    The values defined for each database.history.producer and database.history.consumer parameters are already set to work with the predefined truststore and keystore created in the Aiven for Apache Kafka nodes. Modifying these values is not recommended.

  • key.converter and value.converter: Defines the messages data format in the Apache Kafka topic. The io.confluent.connect.avro.AvroConverter converter pushes messages in Avro format. To store the message schemas, Aiven's Karapace schema registry is used, specified by the schema.registry.url parameter and related credentials.


    The key.converter and value.converter sections are only needed when pushing data in Avro format. Otherwise, messages default to JSON format.

    The USER_INFO is not a placeholder and does not require any parameter substitution.

Create a Kafka Connect connector with the Aiven Console

To create a Kafka Connect connector, follow these steps:

  1. Log in to the Aiven Console.

  2. Select the Aiven for Apache Kafka® or Aiven for Apache Kafka Connect® service to define the connector.

  3. Select Connectors from the sidebar.

  4. Select Create New Connector, which is available only for services that have Apache Kafka Connect enabled.

  5. Select Debezium - SQL Server.

  6. In the Common tab, locate the Connector configuration text box and select on Edit.

  7. Paste the connector configuration (stored in the debezium_source_sql_server.json file) in the form.

  8. Select Apply.


    The Aiven Console reads through the configuration file and automatically populates the relevant UI fields. You can view and modify these fields across different tabs. Any change you make is reflected in JSON format within the Connector configuration text box.

  9. After all the settings are correctly configured, select Create connector.


    With Aiven for Apache Kafka, topics are not created automatically. You have two options:

  10. Verify the connector status under the Connectors screen.

  11. Verify the presence of the data in the target Apache Kafka topic coming from the MySQL dataset. The topic name is equal to concatenation of the database and table name. To change the target table name, you can use Apache Kafka Connect RegexRouter transformation.


You can also create connectors using the Aiven CLI command.