Skip to main content

kafka_consumers

Contains information about Kafka consumers. Applicable for Kafka table engine (native ClickHouse integration)

Columns:

  • database (String) - database of the table with Kafka Engine.
  • table (String) - name of the table with Kafka Engine.
  • consumer_id (String) - Kafka consumer identifier. Note, that a table can have many consumers. Specified by kafka_num_consumers parameter.
  • assignments.topic (Array(String)) - Kafka topic.
  • assignments.partition_id (Array(Int32)) - Kafka partition id. Note, that only one consumer can be assigned to a partition.
  • assignments.current_offset (Array(Int64)) - current offset.
  • exceptions.time, (Array(DateTime)) - timestamp when the 10 most recent exceptions were generated.
  • exceptions.text, (Array(String)) - text of 10 most recent exceptions.
  • last_poll_time, (DateTime) - timestamp of the most recent poll.
  • num_messages_read, (UInt64) - number of messages read by the consumer.
  • last_commit_time, (DateTime) - timestamp of the most recent poll.
  • num_commits, (UInt64) - total number of commits for the consumer.
  • last_rebalance_time, (DateTime) - timestamp of the most recent Kafka rebalance
  • num_rebalance_revocations, (UInt64) - number of times the consumer was revoked its partitions
  • num_rebalance_assignments, (UInt64) - number of times the consumer was assigned to Kafka cluster
  • is_currently_used, (UInt8) - consumer is in use
  • last_used, (UInt64) - last time this consumer was in use, unix time in microseconds
  • rdkafka_stat (String) - library internal statistic. See https://github.com/ClickHouse/librdkafka/blob/master/STATISTICS.md . Set statistics_interval_ms to 0 disable, default is 3000 (once in three seconds).

Example:

SELECT *
FROM system.kafka_consumers
FORMAT Vertical
Row 1:
──────
database: test
table: kafka
consumer_id: ClickHouse-instance-test-kafka-1caddc7f-f917-4bb1-ac55-e28bd103a4a0
assignments.topic: ['system_kafka_cons']
assignments.partition_id: [0]
assignments.current_offset: [18446744073709550615]
exceptions.time: []
exceptions.text: []
last_poll_time: 2006-11-09 18:47:47
num_messages_read: 4
last_commit_time: 2006-11-10 04:39:40
num_commits: 1
last_rebalance_time: 1970-01-01 00:00:00
num_rebalance_revocations: 0
num_rebalance_assignments: 1
is_currently_used: 1
rdkafka_stat: {...}