Pub/sub vs streams comparison in Redis - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to subscribe to a Redis channel named 'news'.

Redis

SUBSCRIBE [1]

Drag options to blanks, or click blank then click option'

Anews

Bstream

Cchannel1

Dmessages

Attempts:

3 left

💡 Hint

Common Mistakes

Using a stream name instead of a channel name

Misspelling the channel name

The SUBSCRIBE command listens to a specific channel. Here, 'news' is the channel name.

2fill in blank

medium

Complete the code to add a message to a Redis stream named 'mystream'.

Redis

XADD mystream * [1] message

Drag options to blanks, or click blank then click option'

Atopic

Bchannel

Cfield1

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using channel or topic which are for pub/sub

Omitting the field name

The XADD command adds an entry to a stream. 'field1' is the field name for the message.

3fill in blank

hard

Fix the error in the command to read messages from a stream 'mystream' starting from the last ID.

Redis

XREAD COUNT 10 STREAMS mystream [1]

Drag options to blanks, or click blank then click option'

A0

B-

C*

D$

Attempts:

3 left

💡 Hint

Common Mistakes

Using '0' to read only new messages

Using '*' which is invalid here

The XREAD command uses '$' to read new messages added after the command runs.

4fill in blank

hard

Fill both blanks to publish a message 'Hello' to channel 'chatroom' and add the same message to stream 'chatstream'.

Redis

PUBLISH [1] 'Hello'
XADD [2] * message 'Hello'

Drag options to blanks, or click blank then click option'

Achatroom

Bchatstream

Cnews

Dmystream

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up channel and stream names

Using the wrong command for each data type

PUBLISH sends a message to a channel, and XADD adds a message to a stream. Here, 'chatroom' is the channel and 'chatstream' is the stream.

5fill in blank

hard

Fill all three blanks to create a consumer group 'group1' for stream 'orders', read new messages, and acknowledge message ID '1526985058136-0'.

Redis

XGROUP CREATE [1] [2] $ MKSTREAM
XREADGROUP GROUP [1] consumer1 COUNT 10 STREAMS [2] >
XACK [2] [1] 1526985058136-0

Drag options to blanks, or click blank then click option'

Agroup1

Borders

Cgroup2

Dmystream

Attempts:

3 left

💡 Hint

Common Mistakes

Using different group or stream names in commands

Not acknowledging messages properly

XGROUP CREATE creates a consumer group named 'group1' for the stream 'orders'. XREADGROUP reads messages for that group, and XACK acknowledges a message ID for the same group and stream.