EXPIRE

EXPIRE key seconds

Set a timeout on key. After the timeout has expired, the key will automatically be deleted. A key with an associated timeout is often said to be volatile in Redis terminology.

The timeout will only be cleared by commands that delete or overwrite the contents of the key, including DEL, SET, GETSET and all the *STORE commands. This means that all the operations that conceptually alter the value stored at the key without replacing it with a new one will leave the timeout untouched. For instance, incrementing the value of a key with INCR will leave the timeout untouched.

The timeout can also be cleared, turning the key back into a persistent key, using the PERSIST command.

If a key is renamed with RENAME, the associated time to live is transferred to the new key name.

If a key is overwritten by RENAME, like in the case of an existing key Key_A that is overwritten by a call like RENAME Key_B Key_A, it does not matter if the original Key_A had a timeout associated or not, the new key Key_A will inherit all the characteristics of Key_B.

Refreshing expires

It is possible to call EXPIRE using as argument a key that already has an existing expire set. In this case the time to live of a key is updated to the new value. There are many useful applications for this, an example is documented in the Navigation session pattern section below.

Return value

Integer reply, specifically:

• 1 if the timeout was set.
• 0 if key does not exist or the timeout could not be set.

Examples

> SET mykey "Hello"
OK
> EXPIRE mykey 10
(integer) 1
> TTL mykey
(integer) 10
> SET mykey "Hello World"
OK
> TTL mykey
(integer) -1

Related Commands

APPEND, BITCOUNT, BITOP, BITPOS, DBSIZE, DECR, DECRBY, DEL, EXISTS, EXPIRE, EXPIREAT, FLUSHDB, GET, GETBIT, GETRANGE, GETSET, INCR, INCRBY, INCRBYFLOAT, KEYS, MGET, MSET, MSETNX, PDEL, PERSIST, PEXPIRE, PEXPIREAT, PTTL, RENAME, RENAMENX, SET, SETBIT, SETRANGE, STRLEN, TTL