INCRBY and DECRBY in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command INCRBY do?

INCRBY increases the integer value of a key by a specified amount. If the key does not exist, it is set to 0 before the operation.

beginner

How does DECRBY differ from INCRBY in Redis?

DECRBY decreases the integer value of a key by a specified amount, while INCRBY increases it.

intermediate

What happens if you use INCRBY on a key that holds a non-integer value?

Redis returns an error because INCRBY only works on keys holding string values that represent integers.

beginner

Can INCRBY and DECRBY be used on keys that do not exist?

Yes, Redis treats non-existing keys as 0 before applying INCRBY or DECRBY.

beginner

Write a Redis command to increase the value of key 'score' by 10.

INCRBY score 10

What will Redis do if you run INCRBY on a key that does not exist?

A Return an error

B Do nothing

C Set the key to the increment value

D Delete the key

Redis treats non-existing keys as 0, then adds the increment value.

Which command decreases the value of a key by a specified number?

A DECRBY

B APPEND

C INCR

D INCRBY

DECRBY decreases the integer value of a key by the given amount.

What type of value must a key hold to use INCRBY successfully?

A Integer

B List

C String

D Set

INCRBY works only on keys holding integer values.

If you run DECRBY key 5 on a key with value 3, what will be the new value?

A 8

B -2

C 0

D 5

3 minus 5 equals -2.

Which command would you use to increase a key's value by 1 in Redis?

A APPEND key 1

B DECRBY key 1

C SET key 1

D INCRBY key 1

INCRBY key 1 increases the key's value by 1.

Explain how INCRBY and DECRBY work in Redis and what happens if the key does not exist.

Think about how Redis handles missing keys as zero.

Describe what error conditions might occur when using INCRBY or DECRBY.

Consider the data type Redis expects for these commands.