XREAD for reading entries in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read entries from a Redis stream named 'mystream' starting from the beginning.

Redis

XREAD COUNT 10 STREAMS mystream [1]

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

A0

B$

C1

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '0' will skip existing entries.

Using '-' is invalid as a stream ID.

The '0' means reading from the start of the stream, so XREAD returns all entries from the beginning.

2fill in blank

medium

Complete the code to read entries from multiple streams 'stream1' and 'stream2' starting from their last IDs.

Redis

XREAD STREAMS stream1 stream2 [1] [1]

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

A>

B0

C$

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '0' will read all entries from the start, not just new ones.

Using '-' is not a valid stream ID.

The '>' ID means reading only new entries added after the command runs for each stream.

3fill in blank

hard

Fix the error in the code to read 5 entries from 'mystream' starting after ID '1609459200000-0'.

Redis

XREAD COUNT 5 STREAMS mystream [1]

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

A1609459200000-

B1609459200000-0

C1609459200000-1

D1609459200000

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same ID returns the entry with that ID again.

Using incomplete IDs causes syntax errors.

The ID '1609459200000-1' reads entries after '1609459200000-0'. Using the same ID would return that entry again.

4fill in blank

hard

Fill both blanks to read entries from 'streamA' and 'streamB' starting from the beginning and the last entry respectively.

Redis

XREAD STREAMS streamA streamB [1] [2]

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

A0

B>

C1609459200000-0

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' for both streams reads only new entries, missing old ones.

Using '-' is invalid.

Use '0' to read all entries from 'streamA' from the start, and '>' to read only new entries from 'streamB'.

5fill in blank

hard

Fill all three blanks to read 3 entries from 's1' and 's2' starting from '0-0' and from the latest entry respectively.

Redis

XREAD COUNT [1] STREAMS s1 s2 [2] [3]

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

A5

B3

C>

D0-0

Attempts:

3 left

💡 Hint

Common Mistakes

Using COUNT 5 reads more entries than requested.

Swapping the stream IDs causes wrong reading points.

Read 3 entries (COUNT 3), from 's1' starting from '0-0' (which means from the beginning), and from 's2' starting at the latest entry ('>')