Consumer Groups

Consumer groups track read positions independently, enabling multiple consumers to process the same stream at their own pace.

-- Create consumer groups
CREATE CONSUMER GROUP analytics ON order_changes;
CREATE CONSUMER GROUP billing ON order_changes;

-- Commit offset for a specific partition
COMMIT OFFSET PARTITION 0 AT 42 ON order_changes CONSUMER GROUP analytics;

-- Batch commit all partitions
COMMIT OFFSETS ON order_changes CONSUMER GROUP analytics;

DROP CONSUMER GROUP analytics ON order_changes;

Stream Partitions

SHOW PARTITIONS ON <stream> lists every partition that holds events in the stream's buffer:

SHOW PARTITIONS ON order_changes;

Column	Meaning
`partition_id`	The partition the offsets belong to.
`earliest_offset`	The oldest buffered event's offset.
`latest_offset`	The newest buffered event's offset.
`event_count`	The number of buffered events.

SHOW PARTITIONS FOR <timeseries> is a different statement: it lists a timeseries collection's storage partitions (see Timeseries Engine).

On Topics

Consumer groups also work with durable topics:

CREATE CONSUMER GROUP processors ON order_events;
SELECT * FROM TOPIC order_events CONSUMER GROUP processors LIMIT 100;
COMMIT OFFSETS ON order_events CONSUMER GROUP processors;

Consumers resume from their last committed offset after disconnect.