(PECL memcached >= 2.0.0)
Memcached::decrementByKey — Decrement numeric item's value, stored on a specific server
$server_key,$key,$offset = 1,$initial_value = 0,$expiry = 0
Memcached::decrementByKey() decrements a numeric item's
value by the specified offset. If the item's value
is not numeric, an error will result. If the operation
would decrease the value below 0, the new value will be 0.
Memcached::decrementByKey() will set the item to the
initial_value parameter if the key doesn't exist.
server_keyThe key identifying the server to store the value on or retrieve it from. Instead of hashing on the actual key for the item, we hash on the server key when deciding which memcached server to talk to. This allows related items to be grouped together on a single server for efficiency with multi operations.
keyThe key of the item to decrement.
offsetThe amount by which to decrement the item's value.
initial_valueThe value to set the item to if it doesn't currently exist.
expiryThe expiry time to set on the item.
Returns item's new value on success or false on failure.