How to Use PERSIST Command in Redis to Remove Key Expiration

In Redis, use the PERSIST command to remove the expiration time from a key, making it permanent. This command returns 1 if the timeout was removed and 0 if the key did not have an expiration or does not exist.

Syntax

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

• PERSIST key: Removes the expiration from the specified key.

If the key exists and had an expiration, it becomes persistent (no expiration).

redis

PERSIST key

Example

This example shows how to set a key with expiration and then remove that expiration using PERSIST.

redis

SET mykey "hello"
EXPIRE mykey 10
TTL mykey
PERSIST mykey
TTL mykey

Output

OK
(integer) 1
(integer) 10
(integer) 1
(integer) -1

Common Pitfalls

Common mistakes when using PERSIST include:

• Trying to persist a key that does not exist returns 0 and does nothing.
• Calling PERSIST on a key without expiration also returns 0 because there is no timeout to remove.
• Expecting PERSIST to delete the key instead of removing expiration is incorrect.

redis

PERSIST nonexistingkey
PERSIST mykey_without_expire

Output

(integer) 0
(integer) 0

Quick Reference

Command	Description	Return Value
PERSIST key	Removes expiration from key	1 if timeout removed, 0 otherwise
TTL key	Returns time to live in seconds	Remaining seconds or -1 if no expiration
EXPIRE key seconds	Sets expiration time	1 if set, 0 if key missing

Key Takeaways

Use PERSIST to remove expiration from a Redis key, making it permanent.

PERSIST returns 1 if expiration was removed, 0 if key missing or no expiration.

Check key expiration with TTL before and after using PERSIST.

Do not confuse PERSIST with commands that delete keys; it only removes expiration.

If a key has no expiration, PERSIST has no effect and returns 0.