Optional blockingOptional dataUsed for "database" commands to enforce type checking.
Private loggerMaximum number of parameters allowed. -1 for no maximum.
Minimum number of parameters require.
Optional pubUsed when PUB/SUB is in effect.
Optional signSign is used in commands with a compliment command. The only current example is INCR/DECR. Sign is 1 for INCR and -1 for DECR
Optional txUsed in transactions to enqueue a command.
Every command must implement the execute method.
Available since 1.0.0.
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, pushing a new value into a list with LPUSH, or altering the field value of a hash with HSET are all operations that 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.
Note that calling EXPIRE/PEXPIRE with a non-positive timeout or EXPIREAT/PEXPIREAT with a ime in the past will result in the key being deleted rather than expired (accordingly, the emitted key event will be del, not expired).
NOTE: unit-redis-ness does NOT yet support key events
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.
Differences in Redis prior 2.1.3 In Redis versions prior 2.1.3 altering a key with an expire set using a command altering its value had the effect of removing the key entirely. This semantics was needed because of limitations in the replication layer that are now fixed.
EXPIRE would return 0 and not alter the timeout for a key with a timeout set.