Appends an element to a list only when the list exists.
RPUSHX
key element
[element…]
Inserts specified values at the tail of the list stored at
key
, only if key
already exists and holds a
list. In contrary to RPUSH
, no operation will be performed
when key
does not yet exist.
Integer reply: the length of the list after the push operation.
O(1) for each element added, so O(N) to add N elements when the command is called with multiple arguments.
@fast @list @write
127.0.0.1:6379> RPUSH mylist "Hello"
(integer) 1
127.0.0.1:6379> RPUSHX mylist "World"
(integer) 2
127.0.0.1:6379> RPUSHX myotherlist "World"
(integer) 0
127.0.0.1:6379> LRANGE mylist 0 -1
1) "Hello"
2) "World"
127.0.0.1:6379> LRANGE myotherlist 0 -1
(empty array)
element
arguments.BLMOVE, BLMPOP, BLPOP, BRPOP, LINDEX, LINSERT, LLEN, LMOVE, LMPOP, LPOP, LPOS, LPUSH, LPUSHX, LRANGE, LREM, LSET, LTRIM, RPOP, RPUSH.