system_kafka_consumers: doc

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

@@ -0,0 +1,56 @@
+---
+slug: /en/operations/system-tables/kafka_consumers
+---
+# kafka_consumers
+
+Contains information about Kafka consumers.
+Applicable for [Kafka table engine](../../engines/table-engines/integration/kafka) (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 identificator. 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 partiton id. Note, that only one consumer can be assigned to a partition.
+- `assignments.current_offset` (Array(Int64)) - current offset.
+- `last_exception_time`, (DateTime) - timestamp when the most recent exception was generated.
+- `last_exception`, (String) - text of the most recent exception.
+- `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+- `num_rebalance_revocations`, (UInt64) - number of times the consumer was revoked its partitions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
+
+Example:
+
+``` sql
+SELECT *
+FROM system.kafka_consumers
+FORMAT Vertical
+```
+
+``` text
+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]
+last_exception_time:        1970-01-01 00:00:00
+last_exception:
+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
+
+```