ClickHouse/docs/en/operations/system-tables/kafka_consumers.md

slug
/en/operations/system-tables/kafka_consumers

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• num_rebalance_revocations, (UInt64) - number of times the consumer was revoked its partitions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:               {...}