Latest web development tutorials

Memcached replace command

Memcached replace command is used to replace an existingkey (key) value (data value).

If the key does not exist, replace fail, and you will get a responseNOT_STORED.

grammar:

The basic syntax replace command is as follows: 

replace key flags exptime bytes [noreply]
value

Parameters are as follows:

  • key: key key-value structure key, it is used to find the cache value.
  • flags: may include a key-value pair of integer parameter, the client uses it to store additional information about the key-value pairs.
  • exptime: save key-value pairs in the cache the length of time (in seconds, 0 means forever)
  • bytes: number of bytes stored in the cache
  • noreply (optional): This parameter tells the server does not need to return data
  • value: the value stored (always located in the second row) (can be directly understood as key-value structure value)

Examples

We set the following examples:

  • key → mykey
  • flag → 0
  • exptime → 900 (in seconds)
  • bytes → 10 (the number of bytes of data storage)
  • value → data_value

The following examples keys we use 'mykey' and store the corresponding value data_value. After the execution we replace the same key value 'some_other_value'. 

add mykey 0 900 10
data_value
STORED
get mykey
VALUE mykey 0 10
data_value
END
replace mykey 0 900 16
some_other_value
get mykey
VALUE mykey 0 16
some_other_value
END

Export

If the data is added successfully, the output: 

STORED

Output information Description:

  • STORED: After successfully saved output.
  • NOT_STORED: carries out replacement after failure output.