Determines whether one or more keys exist.
EXISTS
key [key…]
Returns if key
exists.
The user should be aware that if the same existing key is mentioned
in the arguments multiple times, it will be counted multiple times. So
if somekey
exists, EXISTS somekey somekey
will
return 2.
Integer reply: the number of keys that exist from those specified as arguments.
O(N) where N is the number of keys to check.
@fast @keyspace @read
127.0.0.1:6379> SET key1 "Hello"
OK
127.0.0.1:6379> EXISTS key1
(integer) 1
127.0.0.1:6379> EXISTS nosuchkey
(integer) 0
127.0.0.1:6379> SET key2 "World"
OK
127.0.0.1:6379> EXISTS key1 key2 nosuchkey
(integer) 2
key
arguments.COPY, DEL, DUMP, EXPIRE, EXPIREAT, EXPIRETIME, KEYS, MIGRATE, MOVE, OBJECT, OBJECT ENCODING, OBJECT FREQ, OBJECT HELP, OBJECT IDLETIME, OBJECT REFCOUNT, PERSIST, PEXPIRE, PEXPIREAT, PEXPIRETIME, PTTL, RANDOMKEY, RENAME, RENAMENX, RESTORE, SCAN, SORT, SORT_RO, TOUCH, TTL, TYPE, UNLINK, WAIT, WAITAOF.