Memcached replace command

The Memcached replace command is used to replace an existingkeyofvalue (data value)。

If the key does not exist, the replacement fails, and you will receive a responseNOT_STORED。

Syntax:

The basic syntax format of the replace command is as follows:

replace key flags exptime bytes [noreply]
value

The parameter descriptions are as follows:

  • key：The key in the key-value structure, used to look up the cached value.
  • flags: An integer parameter that can include key-value pairs; the client uses it to store additional information about the key-value pair.
  • exptime: The length of time (in seconds) to store the key-value pair in the cache; 0 means forever.
  • bytes: The number of bytes stored in the cache.
  • noreply (optional): This parameter tells the server not to return data.
  • value: The stored value (always on the second line) (can be directly understood as the value in the key-value structure).

Examples

In the following example, we set:

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

In the following example, we use the key 'mykey' and store the corresponding value data_value. After execution, we replace the value of the same key with '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

Output

If the data is added successfully, the output is:

STORED

Output information description:

  • STORED: Output after saving successfully.
  • NOT_STORED: Output after a failed replacement.
Other extensions