LTRIM for list capping in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to trim the list 'mylist' to keep only the first 100 elements.

Redis

LTRIM mylist 0 [1]

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

A101

B100

C-1

D99

Attempts:

3 left

💡 Hint

Common Mistakes

Using 100 as the end index which keeps 101 elements.

Using negative indexes incorrectly.

The LTRIM command keeps elements from the start index to the end index inclusive. To keep the first 100 elements, the end index should be 99 (since indexing starts at 0).

2fill in blank

medium

Complete the code to keep only the last 50 elements of the list 'events'.

Redis

LTRIM events [1] -1

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

A-49

B0

C-50

D49

Attempts:

3 left

💡 Hint

Common Mistakes

Using -50 as start index which keeps 51 elements.

Using positive indexes which may not keep last elements.

Using negative indexes, -1 is the last element, so to keep last 50 elements, start at -49.

3fill in blank

hard

Fix the error in the command to keep only the first 10 elements of 'tasks'.

Redis

LTRIM tasks 0 [1]

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

A10

B-10

C9

D-9

Attempts:

3 left

💡 Hint

Common Mistakes

Using 10 as end index which keeps 11 elements.

Using negative indexes incorrectly.

The end index is inclusive and zero-based, so to keep 10 elements, the end index must be 9.

4fill in blank

hard

Fill both blanks to trim 'logs' list to keep elements from index 5 to 15.

Redis

LTRIM logs [1] [2]

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

A5

B15

C10

D20

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping start and end indexes.

Using indexes outside the list range.

The command keeps elements starting at index 5 and ending at index 15 inclusive.

5fill in blank

hard

Fill all three blanks to trim 'queue' list to keep elements from index 2 to 12.

Redis

LTRIM [1] [2] [3]

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

Aqueue

B2

C12

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong list name.

Incorrect start or end indexes.

The command trims the list named 'queue' from index 2 to 12 inclusive.