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GETSET key value

相关命令

始于1.0.0可用。

时间复杂度： O(1)

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.

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":

redis> INCR mycounter 

  1. (integer) 1

redis> GETSET mycounter "0" 

  1. "1"

redis> GET mycounter 

  1. "0"
redis>

返回值

Bulk string reply: the old value stored at key, or nil when key did not exist.

例子

redis> SET mykey "Hello" 

  1. OK

redis> GETSET mykey "World" 

  1. "Hello"

redis> GET mykey 

  1. "World"
redis>

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