ZINCRBY for score updates in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command ZINCRBY do?

It increases the score of a member in a sorted set by a given amount. If the member does not exist, it is added with the increment as its score.

beginner

How do you increase the score of member 'player1' by 10 in a sorted set 'game_scores'?

Use the command: ZINCRBY game_scores 10 player1.

beginner

What happens if you use ZINCRBY on a member that does not exist in the sorted set?

The member is added to the sorted set with the score equal to the increment value.

intermediate

Can ZINCRBY decrease a member's score? How?

Yes, by using a negative increment value. For example, ZINCRBY game_scores -5 player1 decreases player1's score by 5.

beginner

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

It works with sorted sets, which store members ordered by their scores.

What does the Redis command ZINCRBY myset 3 member1 do?

A Removes 'member1' from 'myset'

B Adds 3 to the score of 'member1' in 'myset', or adds 'member1' with score 3 if not present

C Sets the score of 'member1' to 3 in 'myset' regardless of previous score

D Returns the current score of 'member1' in 'myset'

ZINCRBY increases the score of the member by the given increment or adds it with that score if it doesn't exist.

If you run ZINCRBY leaderboard -2 player42, what happens?

A The score of 'player42' increases by 2

B 'player42' is removed from 'leaderboard'

C An error occurs because increment cannot be negative

D The score of 'player42' decreases by 2

ZINCRBY accepts negative increments to decrease a member's score.

Which Redis data type is required to use ZINCRBY?

A List

B Hash

C Sorted Set

D String

ZINCRBY works only with sorted sets.

What will ZINCRBY scores 5 newplayer do if 'newplayer' is not in 'scores'?

A Add 'newplayer' with score 5

B Add 'newplayer' with score 0

C Do nothing

D Return an error

If the member does not exist, ZINCRBY adds it with the increment as its score.

What does the return value of ZINCRBY represent?

A The new score of the member after increment

B The old score before increment

C The total number of members in the sorted set

D The rank of the member in the sorted set

ZINCRBY returns the updated score of the member.

Explain how the Redis command ZINCRBY updates scores in a sorted set.

Think about how scores change and what happens if the member is new.

Describe a real-life example where you might use ZINCRBY in a Redis sorted set.

Imagine a game where players earn points over time.