- Usage:
-
GETSET key value
- Complexity:
- O(1)
- Since:
- 1.0.0
Atomically sets key to value and returns the old value stored at key.
Returns an error when key exists but does not hold a string value. Any
previous time to live associated with the key is discarded on successful
SET operation.
Design pattern
GETSET can be used together with INCR for counting with atomic reset.
For example: a process may call INCR against the key mycounter every time
some event occurs, but from time to time we need to get the value of the counter
and reset it to zero atomically.
This can be done using GETSET mycounter "0":
127.0.0.1:6379> INCR mycounter
(integer) 1
127.0.0.1:6379> GETSET mycounter "0"
"1"
127.0.0.1:6379> GET mycounter
"0"
Examples
127.0.0.1:6379> SET mykey "Hello"
OK
127.0.0.1:6379> GETSET mykey "World"
"Hello"
127.0.0.1:6379> GET mykey
"World"