How to Set Expiration on Key in Redis: Simple Guide

To set expiration on a key in Redis, use the EXPIRE command followed by the key name and the time in seconds. This makes the key automatically delete after the specified time. You can also use SET with the EX option to set a key with expiration in one step.

Syntax

The main command to set expiration on a key is EXPIRE key seconds. Here, key is the name of the key, and seconds is how long Redis keeps the key before deleting it automatically.

You can also set expiration when creating a key using SET key value EX seconds, which sets the key and expiration together.

redis

EXPIRE mykey 60

SET mykey "hello" EX 60

Example

This example shows how to set a key with a value and then set it to expire after 10 seconds. After 10 seconds, the key will no longer exist.

redis

SET session_token "abc123"
EXPIRE session_token 10
TTL session_token

Output

(integer) 10

Common Pitfalls

• Setting expiration on a key that does not exist returns 0 and does nothing.
• Using EXPIRE with a negative or zero time deletes the key immediately.
• For persistent keys, remember expiration is in seconds, not milliseconds (use PEXPIRE for milliseconds).

redis

EXPIRE missing_key 10  # returns 0 because key does not exist

EXPIRE mykey 0         # deletes mykey immediately

Quick Reference

Command	Description
EXPIRE key seconds	Set expiration time in seconds on an existing key
PEXPIRE key milliseconds	Set expiration time in milliseconds on an existing key
SET key value EX seconds	Set key with value and expiration in seconds
TTL key	Check remaining time to live of a key in seconds
PERSIST key	Remove expiration from a key

Key Takeaways

Use EXPIRE to set expiration time in seconds on existing keys.

Use SET with EX option to set key and expiration together.

Expiration time is in seconds; use PEXPIRE for milliseconds.

EXPIRE returns 0 if the key does not exist.

Use TTL to check how much time is left before a key expires.