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system.dead_letter_queue

Contains information about messages received via a streaming engine and parsed with errors. Currently implemented for Kafka and RabbitMQ.

Logging is enabled by specifying dead_letter_queue for the engine specific handle_error_mode setting.

The flushing period of data is set in flush_interval_milliseconds parameter of the dead_letter_queue server settings section. To force flushing, use the SYSTEM FLUSH LOGS query.

ClickHouse does not delete data from the table automatically. See Introduction for more details.

Columns:

  • table_engine (Enum8) - Stream type. Possible values: Kafka and RabbitMQ.
  • event_date (Date) - Message consuming date.
  • event_time (DateTime) - Message consuming date and time.
  • event_time_microseconds (DateTime64) - Message consuming time with microseconds precision.
  • database (LowCardinality(String)) - ClickHouse database the streaming table belongs to.
  • table (LowCardinality(String)) - ClickHouse table name.
  • error (String) - Error text.
  • raw_message (String) - Message body.
  • kafka_topic_name (String) - Kafka topic name.
  • kafka_partition (UInt64) - Kafka partition of the topic.
  • kafka_offset (UInt64) - Kafka offset of the message.
  • kafka_key (String) - Kafka key of the message.
  • rabbitmq_exchange_name (String) - RabbitMQ exchange name.
  • rabbitmq_message_id (String) - RabbitMQ message id.
  • rabbitmq_message_timestamp (DateTime) - RabbitMQ message timestamp.
  • rabbitmq_message_redelivered (UInt8) - RabbitMQ redelivered flag.
  • rabbitmq_message_delivery_tag (UInt64) - RabbitMQ delivery tag.
  • rabbitmq_channel_id (String) - RabbitMQ channel id.

Example

Query:

Result:

See Also

  • Kafka - Kafka Engine
  • system.kafka_consumers — Description of the kafka_consumers system table which contains information like statistics and errors about Kafka consumers.