Returns the previous string value of a key after setting it to a new value.
GETSET
key value
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.
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"
One of the following:
Bulk string reply: the old value stored at the key.
Nil reply: if the key does not exist.
One of the following:
Bulk string reply: the old value stored at the key.
Null reply: if the key does not exist.
O(1)
@fast @string @write
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"
SET
with the
GET
argument.APPEND, DECR, DECRBY, GET, GETDEL, GETEX, GETRANGE, INCR, INCRBY, INCRBYFLOAT, LCS, MGET, MSET, MSETNX, SET, SETRANGE, STRLEN.