Redis Series Learning note 9-Key expiration feature

Key expiration feature

Let Redis automatically delete specific keys at a specified time. key expiration feature related commands

type	Command
Set the time to live	EXPIRE command and Pexpire command.
Set Expiration Time	expireat command and Pexpireat command.
View remaining live time	The TTL command and the Pttl command.
Delete Time to live or expire	PERSIST command.

EXPIRE Key seconds

Sets the time-to-live of key keys to the specified number of seconds.

Pexpire key milliseconds

Sets the time-to-live of key key to the specified number of milliseconds.

If the given key does not exist, then EXPIRE and Pexpire will return 0, indicating that the setting failed, and that if the command returns 1, the setting is successful.

Expireat key Timestamp

Set the expiration time for key key to the specified second-level UNIX timestamp.

Pexpireat Key Milliseconds-timestamp

Sets the expiration time for key key to the specified millisecond-level UNIX timestamp.

If the given key does not exist, then expireat and Pexpireat will return 0, indicating that the setting failed, and that if the command returns 1, the setting is successful.

TTL Key

Returns the remaining lifetime of the key, in seconds.

Pttl Key

Returns the remaining life time of the key, in milliseconds.

TTL and Pttl may return three different values:

return value	meaning
-2	The key does not exist.
-1	The key exists but does not set the expiration time or the time to live.
= 0	The remaining life time of the key.

PERSIST Key

Removes the expiration time or the lifetime of the key set, making it not automatically deleted by Redis. application of key expiration function

Automatically updates the cache, automatically refreshes the leaderboard, and periodically deletes the user Session.

Setex Key seconds value

The value of the SET key key is value,seconds seconds after expiration

Psetex Key milliseconds value

The value of the SET key key is value,milliseconds milliseconds after expiration

Although both Setex and Psetex are working normally, I recommend using set instead of Setex or Psetex as much as possible, because using set to set the time to live is more concise, whereas older Setex and Psetex may be discarded in the future.