Consumer groups concept in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a consumer group in Redis Streams?

A consumer group is a way to allow multiple clients to share the work of processing messages from a Redis Stream. Each consumer in the group gets a subset of messages to process, so the workload is divided.

intermediate

How does Redis ensure that messages are not lost when using consumer groups?

Redis keeps track of which messages each consumer has acknowledged. Messages remain pending until acknowledged, so if a consumer fails, another can claim and process those messages.

beginner

What command creates a consumer group in Redis Streams?

The command is XGROUP CREATE <stream> <groupname> <id>. It creates a new consumer group for the given stream starting at the specified ID.

intermediate

What is the role of the XREADGROUP command?

XREADGROUP lets a consumer read messages from a stream as part of a consumer group. It assigns messages to that consumer and tracks them as pending until acknowledged.

advanced

How can a consumer claim pending messages from another consumer in the same group?

Using the XCLAIM command, a consumer can take ownership of pending messages that were assigned to another consumer but not acknowledged, helping to recover unprocessed messages.

What does a consumer group in Redis Streams help you do?

A Store messages permanently

B Divide message processing among multiple consumers

C Encrypt messages automatically

D Send messages to external databases

Consumer groups allow multiple consumers to share the work of processing messages from a stream.

Which command creates a consumer group in Redis?

A XACK

B XREADGROUP

C XGROUP CREATE

D XCLAIM

XGROUP CREATE is used to create a new consumer group.

What happens to messages in a consumer group before they are acknowledged?

A They are marked as pending

B They are deleted immediately

C They are sent to all consumers

D They are ignored

Messages remain pending until a consumer acknowledges them.

Which command lets a consumer read messages as part of a consumer group?

A XDEL

B XGROUP CREATE

C XADD

D XREADGROUP

XREADGROUP reads messages assigned to a consumer in a group.

How can a consumer recover messages that another consumer did not acknowledge?

A Using XCLAIM

B Using XADD

C Using XGROUP CREATE

D Using XREAD

XCLAIM lets a consumer claim pending messages from others.

Explain how consumer groups help distribute message processing in Redis Streams.

Think about how a team divides tasks to work faster.

Describe the lifecycle of a message in a Redis Stream when using consumer groups.

Follow the message from arrival to processing and acknowledgment.