TOUCH
Syntax
TOUCH key [key ...]
Time complexity: O(N) where N is the number of keys that will be touched.
Alters the last access time of a key(s). A key is ignored if it does not exist.
Return
Integer reply: The number of keys that were touched.
Examples
dragonfly> SET key1 "Hello"
"OK"
dragonfly> SET key2 "World"
"OK"
dragonfly> TOUCH key1 key2
(integer) 2