ZREM for removal in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command ZREM do?

The ZREM command removes one or more members from a sorted set in Redis.

beginner

How does ZREM affect the sorted set if the member does not exist?

If the member does not exist in the sorted set, ZREM does nothing and returns 0.

beginner

What is the return value of ZREM?

ZREM returns the number of members that were removed from the sorted set.

intermediate

Can ZREM remove multiple members at once?

Yes, ZREM can remove multiple members in a single command by listing them all.

intermediate

What happens if you remove all members from a sorted set using ZREM?

If all members are removed, the sorted set becomes empty and Redis deletes the key automatically.

What does the Redis command ZREM myset member1 do?

A Removes 'member1' from the sorted set 'myset'

B Adds 'member1' to the sorted set 'myset'

C Returns the score of 'member1' in 'myset'

D Deletes the entire sorted set 'myset'

ZREM removes specified members from a sorted set. Here, it removes 'member1' from 'myset'.

If you run ZREM myset memberX but 'memberX' is not in 'myset', what happens?

A Redis returns an error

B Redis removes a random member

C Redis returns 0 and does nothing

D Redis deletes the entire set

If the member does not exist, ZREM returns 0 and does not change the set.

What does ZREM myset member1 member2 do?

A Adds 'member1' and 'member2' to 'myset'

B Removes both 'member1' and 'member2' from 'myset'

C Returns the scores of 'member1' and 'member2'

D Removes only 'member1' from 'myset'

ZREM can remove multiple members at once by listing them all.

What is the return value of ZREM?

A The number of members removed

B The total number of members in the set

C The score of the removed member

D Always 1

ZREM returns how many members were actually removed from the set.

What happens if you remove all members from a sorted set using ZREM?

A The sorted set remains empty but the key stays

B The sorted set resets scores to zero

C Redis throws an error

D Redis deletes the key automatically

When a sorted set becomes empty, Redis deletes the key automatically.

Explain how the Redis command ZREM works and what it returns.

Think about removing items from a list and what feedback you get.

Describe what happens to a sorted set key in Redis when all its members are removed using ZREM.

Consider what happens to an empty container in real life.