SPOP for random removal in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command SPOP do?

The SPOP command removes and returns one or more random elements from a set stored at a given key.

beginner

How do you remove 3 random elements from a Redis set named myset?

Use the command: SPOP myset 3. This removes and returns 3 random elements from myset.

intermediate

What happens if you use SPOP with a count larger than the set size?

Redis returns and removes all elements in the set without error, even if the count is larger than the set size.

beginner

Can SPOP be used on a key that does not exist?

Yes. If the key does not exist or is empty, SPOP returns null or an empty array, depending on the count argument.

intermediate

Why might you use SPOP instead of SRANDMEMBER?

SPOP removes the element from the set, while SRANDMEMBER only returns a random element without removing it.

What does the Redis command SPOP myset do?

A Removes and returns a random element from <code>myset</code>

B Returns a random element from <code>myset</code> without removing it

C Removes all elements from <code>myset</code>

D Adds a random element to <code>myset</code>

SPOP removes and returns a random element from the set.

If you run SPOP myset 5 but myset only has 3 elements, what happens?

A Returns 5 elements and errors

B Returns nothing

C Returns 3 elements and removes them all

D Returns 5 elements but does not remove any

Redis returns and removes all 3 elements without error.

Which command removes a random element from a Redis set?

A SADD

B SRANDMEMBER

C SREM

D SPOP

SPOP removes and returns a random element.

What does SPOP return if the set is empty?

A An error

B Null or empty array

C The last element

D The whole set

If the set is empty, SPOP returns null or an empty array.

How is SPOP different from SRANDMEMBER?

A <code>SPOP</code> removes elements, <code>SRANDMEMBER</code> does not

B <code>SRANDMEMBER</code> removes elements, <code>SPOP</code> does not

C Both do the same thing

D <code>SPOP</code> adds elements, <code>SRANDMEMBER</code> removes them

SPOP removes and returns elements; SRANDMEMBER only returns elements without removing.

Explain how the Redis SPOP command works and when you might use it.

Think about removing random items from a collection.

Describe the difference between SPOP and SRANDMEMBER in Redis.

One changes the set, the other does not.