How to Use DECR Command in Redis: Syntax and Examples

Use the DECR command in Redis to decrease the integer value stored at a key by one. If the key does not exist, it is set to 0 before decrementing, resulting in -1. The command returns the new value after decrement.

Syntax

The DECR command syntax is simple and requires only the key name as an argument.

• DECR key: Decreases the integer value of key by 1.

If the key does not exist, Redis treats it as 0 before decrementing. The key must hold a string representing an integer, or an error will occur.

redis

DECR key

Example

This example shows how to use DECR to decrease a counter stored in Redis.

redis

SET counter 10
DECR counter
GET counter

Output

OK
(integer) 9
"9"

Common Pitfalls

Common mistakes when using DECR include:

• Trying to decrement a key holding a non-integer value, which causes an error.
• Assuming DECR works on keys that hold data types other than strings.
• Not handling the case when the key does not exist, which sets it to -1 after decrement.

redis

SET name "hello"
DECR name

# Correct usage:
SET visits 5
DECR visits

Output

(error) ERR value is not an integer or out of range
OK
(integer) 4

Quick Reference

Command	Description	Returns
DECR key	Decreases integer value of key by 1	New integer value after decrement
If key missing	Key is set to 0 before decrement	-1
Error case	Key holds non-integer value	Error

Key Takeaways

DECR decreases the integer value stored at a key by one and returns the new value.

If the key does not exist, DECR sets it to -1 after decrementing from 0.

The key must hold a string representing an integer; otherwise, DECR returns an error.

DECR only works on string keys storing integers, not other data types.

Use GET after DECR to verify the updated value.