Do you write data to ClickHouse via Kafka?

Yes, writing data to ClickHouse via Kafka is a common pattern for stream data processing.

The idea is that applications publish events to Kafka, and ClickHouse consumes these events through a special Kafka engine, which allows direct reading of data from Kafka topics and writing them into ClickHouse tables.

Example of setting up a table in ClickHouse to read from Kafka:

CREATE TABLE kafka_table (
    key String,
    value String
) ENGINE = Kafka
SETTINGS
    kafka_broker_list = 'kafka1:9092,kafka2:9092',
    kafka_topic_list = 'my_topic',
    kafka_group_name = 'clickhouse_group',
    kafka_format = 'JSONEachRow';

CREATE TABLE target_table AS kafka_table ENGINE = MergeTree() ORDER BY tuple();

-- Then, data from kafka_table can be transferred to target_table using a Materialized View:

CREATE MATERIALIZED VIEW mv TO target_table AS
SELECT * FROM kafka_table;

Thus, data from Kafka automatically flows into ClickHouse for further analysis.