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

The SQL Server Debezium source connector is based on the change data capture (CDC) feature, extracts the database changes captured in specific change tables on a polling interval, and writes them to an Apache Kafka® topic in a standard format where they can be transformed and read by multiple consumers.


You can check the full set of available parameters and configuration options in the connector’s documentation.

Enable CDC in SQL Server#

To use the Debezium source connector for SQL server, you need to enabled at database level and table level the SQL Server Change Data Capture (CDC). This will create the necessary schemas and tables containing a history of all the change events happening to the tables you want 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>'

Once the CDC is enabled, a new schema called cdc is created for the target database, containing all the required 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 setup

  • <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 evolving table schemas in online mode, new columns information might be lost until the CDC is re-enabled for the table. More information are available in the related Debezium documentation.


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

Furthermore you need to collect the following information about the source SQL Server database upfront:

  • 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; the list must be in the form of 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’re using Aiven for SQL Server and Aiven for Apache Kafka 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 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#

Define the connector configurations in a file (we’ll refer to it with the name debezium_source_sql_server.json) with the following content, creating a file is not strictly necessary but allows to have all the information in one place before copy/pasting them in the Aiven Console:

    "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, dictates the prefix that will be used for Apache Kafka topic names. The resulting topic name will be the concatenation 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 will contain the history of schema changes.

  • database.history.kafka.bootstrap.servers: points 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: points 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. Therefore, they should not be changed.

  • 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 messages schema we use Aiven’s Karapace schema registry as 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. If omitted the messages will be defined in JSON format.

    The USER_INFO is not a placeholder, no substitution is needed for that parameter.

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 and select the Aiven for Apache Kafka® or Aiven for Apache Kafka Connect® service where the connector needs to be defined.

  2. Select Connectors from the left sidebar.

  3. Select Create New Connector, the button is enabled only for services with Kafka Connect enabled.

  4. Select Debezium - SQL Server.

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

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

  7. Select Apply.


    The Aiven Console parses the configuration file and fills the relevant UI fields. You can review the UI fields across the various tabs and change them if necessary. The changes will be reflected in JSON format in the Connector configuration text box.

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


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

  9. Verify the connector status under the Connectors screen.

  10. Verify the presence of the data in the target Apache Kafka topic coming from the SQL Server dataset. The topic name is equal to concatenation of the database and table name. If you need to change the target table name, you can do so using the Kafka Connect RegexRouter transformation.


You can also create connectors using the Aiven CLI command.