How to Set Timeout in Redis: Commands and Examples

In Redis, you set a timeout on a key using the EXPIRE command to specify seconds before the key expires. Alternatively, use SET with the EX option to set a key with an expiration in one step. You can also use PEXPIRE to set timeout in milliseconds.

Syntax

Redis provides several commands to set a timeout on keys:

• EXPIRE key seconds: Sets expiration in seconds.
• PEXPIRE key milliseconds: Sets expiration in milliseconds.
• SET key value EX seconds: Sets key with value and expiration in seconds atomically.

These commands make the key automatically deleted after the timeout.

redis

EXPIRE mykey 60
PEXPIRE mykey 1500
SET mykey "value" EX 30

Example

This example shows how to set a key with a 10-second timeout using EXPIRE and how to set a key with expiration using SET with EX option.

redis

127.0.0.1:6379> SET session_token "abc123"
OK
127.0.0.1:6379> EXPIRE session_token 10
(integer) 1
127.0.0.1:6379> TTL session_token
(integer) 10

127.0.0.1:6379> SET cache_item "data" EX 5
OK
127.0.0.1:6379> TTL cache_item
(integer) 5

Output

(integer) 1
(integer) 10
OK
(integer) 5

Common Pitfalls

Common mistakes when setting timeouts in Redis include:

• Using EXPIRE on a key that does not exist returns 0 and does not set timeout.
• Setting expiration with SET without EX or PX option does not set timeout.
• Confusing seconds and milliseconds when using EXPIRE vs PEXPIRE.

redis

127.0.0.1:6379> EXPIRE missing_key 10
(integer) 0

# Correct way to set key and expiration together
127.0.0.1:6379> SET new_key "value" EX 10
OK

Output

(integer) 0
OK

Quick Reference

Command	Description	Timeout Unit
EXPIRE key seconds	Set expiration time in seconds	Seconds
PEXPIRE key milliseconds	Set expiration time in milliseconds	Milliseconds
SET key value EX seconds	Set key with value and expiration in seconds	Seconds
TTL key	Get remaining time to live in seconds	Seconds
PTTL key	Get remaining time to live in milliseconds	Milliseconds

Key Takeaways

Use EXPIRE to set timeout in seconds on existing keys.

Use SET with EX option to set key and timeout atomically.

PEXPIRE sets timeout in milliseconds for finer control.

Check TTL to see how much time is left before expiration.

EXPIRE returns 0 if the key does not exist, so ensure key exists first.