LINDEX for position access in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command LINDEX do?

The LINDEX command returns the element at a specific position (index) in a Redis list.

beginner

How does Redis count positions in a list when using LINDEX?

Positions start at 0 for the first element. Negative numbers count from the end, with -1 being the last element.

beginner

What will LINDEX mylist 2 return if mylist contains ["a", "b", "c", "d"]?

It will return "c", the element at index 2 (third element).

beginner

What happens if you use LINDEX with an index that is out of range?

Redis returns null because there is no element at that position.

beginner

Can LINDEX be used to modify elements in a Redis list?

No, LINDEX only reads an element. To modify, use LSET.

What index does LINDEX use to get the first element of a list?

A -2

B 1

C -1

D 0

Redis lists start at index 0 for the first element.

What does LINDEX mylist -1 return?

A The first element

B The last element

C The second element

D An error

Negative indexes count from the end; -1 is the last element.

If mylist has 3 elements, what does LINDEX mylist 5 return?

A null

B The last element

C The 6th element

D An error message

Index 5 is out of range, so Redis returns null.

Which command would you use to change an element at a specific position in a Redis list?

A LINDEX

B LPUSH

C LSET

D LRANGE

LSET modifies an element at a given index.

What type of data structure does LINDEX work with in Redis?

A Lists

B Hashes

C Strings

D Sets

LINDEX accesses elements in Redis lists.

Explain how the LINDEX command works in Redis and how indexing is handled.

Think about how you count positions in a list from front and back.

Describe what happens when you use LINDEX with an index that does not exist in the list.

What does Redis do when you ask for something that is not there?