Overview of data delivery

RisingWave supports delivering data to downstream systems via its sink connectors.

To stream data out of RisingWave, you must create a sink. A sink is an external target that you can send data to. Use the CREATE SINK statement to create a sink. You need to specify what data to be exported, the format, and the sink parameters.

Currently, RisingWave supports the following sink connectors:

• Apache Doris sink connector (connector = 'doris')

  With this connector, you can sink data from RisingWave to Apache Doris. For details about the syntax and parameters, see Sink data to Apache Doris.

• Apache Iceberg sink connector (connector = 'iceberg')

  With this connector, you can sink data from RisingWave to Apache Iceberg. For details about the syntax and parameters, see Sink data to Apache Iceberg.

• AWS Kinesis sink connector (connector = 'kinesis')

  With this connector, you can sink data from RisingWave to AWS Kinesis. For details about the syntax and parameters, see Sink data to AWS Kinesis.

• Cassandra and ScyllaDB sink connector (connector = 'cassandra')

  With this connector, you can sink data from RisingWave to Cassandra or ScyllaDB. For details about the syntax and parameters, see Sink data to Cassandra or ScyllaDB.

• ClickHouse sink connector (connector = 'clickhouse')

  With this connector, you can sink data from RisingWave to ClickHouse. For details about the syntax and parameters, see Sink data to ClickHouse.

• Delta Lake sink connector (connector = 'deltalake')

  With this connector, you can sink data from RisingWave to Delta Lake. For details about the syntax and parameters, see Sink data to Delta Lake.

• Elasticsearch sink connector (connector = 'elasticsearch')

  With this connector, you can sink data from RisingWave to Elasticsearch. For details about the syntax and parameters, see Sink data to Elasticsearch.

• JDBC sink connector for MySQL, PostgreSQL, or TiDB (connector = 'jdbc')

  With this connector, you can sink data from RisingWave to JDBC-available databases, such as MySQL, PostgreSQL, or TiDB. When sinking to a database with a JDBC driver, ensure that the corresponding table created in RisingWave has the same schema as the table in the database you are sinking to. For details about the syntax and parameters, see Sink to MySQL, Sink to PostgreSQL, or Sink to TiDB.

• Kafka sink connector (connector = 'kafka')

  With this connector, you can sink data from RisingWave to Kafka topics. For details about the syntax and parameters, see Sink data to Kafka.

• NATS sink connector (connector = 'nats')

  With this connector, you can sink data from RisingWave to NATS. For details about the syntax and parameters, see Sink data to NATS.

• Pulsar sink connector (connector = 'pulsar')

  With this connector, you can sink data from RisingWave to Pulsar. For details about the syntax and parameters, see Sink data to Pulsar.

Sink decoupling

The sink_decouple session variable can be specified to enable or disable sink decoupling. The default value for the session variable is default.

To enable sink decoupling for all sinks created in the sessions, set sink_decouple as true or enable.

SET sink_decouple = true;

To disable sink decoupling, set sink_decouple as false or disable, regardless of the default setting.

SET sink_decouple = false;

Upsert sinks and primary keys

For each sink, you can specify the data format. All sinks supports the upsert and append-only formats while Kafka also supports the debezium format. When creating an upsert sink, note whether or not you need to specify the primary key in the following situations.

• If the downstream system supports primary keys and the table in the downstream system has a primary key, you must specify the primary key with the primary_key field when creating an upsert JDBC sink.

• If the downstream system supports primary keys but the table in the downstream system has no primary key, then RisingWave does not allow users to create an upsert sink. A primary key must be defined in the table in the downstream system.

• If the downstream system does not support primary keys, then users must define the primary key when creating an upsert sink.