PERSIST to remove expiry in Redis

Introduction

Sometimes you want to keep a key forever in Redis without it disappearing after a set time. PERSIST helps by removing any expiration time from a key.

You set a temporary key but then decide to keep it permanently.

You want to stop a countdown timer on a key so it doesn't expire.

You accidentally set an expiry and want to undo it.

You want to make sure important data stays in Redis without disappearing.

Syntax

Redis

PERSIST key

This command removes the expiration from the given key.

If the key does not have an expiration, PERSIST does nothing and returns 0.

Examples

Removes the expiration from 'mykey' so it stays forever.

Redis

PERSIST mykey

Stops the expiration timer on 'session123' key.

Redis

PERSIST session123

Sample Program

We create a key 'tempkey' with value 'hello'. Then we set it to expire in 10 seconds. TTL shows the time left. PERSIST removes the expiry. TTL after PERSIST returns -1, meaning no expiry.

Redis

SET tempkey "hello"
EXPIRE tempkey 10
TTL tempkey
PERSIST tempkey
TTL tempkey

Important Notes

TTL command returns -1 if the key has no expiration.

PERSIST returns 1 if expiration was removed, 0 if key had no expiration or does not exist.

Removing expiry means the key will stay until deleted manually.

Summary

PERSIST removes the expiration time from a Redis key.

Use it to keep keys permanently after setting expiry.

Check TTL before and after to see the effect.