LPUSHX · Valkey

LPUSHX

Prepends one or more elements to a list only when the list exists.

Usage

LPUSHX key element [element…]

Description

Inserts specified values at the head of the list stored at key, only if key already exists and holds a list. In contrary to LPUSH, no operation will be performed when key does not yet exist.

Reply

Integer reply: the length of the list after the push operation.

Complexity

O(1) for each element added, so O(N) to add N elements when the command is called with multiple arguments.

ACL Categories

@fast @list @write

Examples

127.0.0.1:6379> LPUSH mylist "World"
(integer) 1
127.0.0.1:6379> LPUSHX mylist "Hello"
(integer) 2
127.0.0.1:6379> LPUSHX myotherlist "Hello"
(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)

History

See also

BLMOVE, BLMPOP, BLPOP, BRPOP, LINDEX, LINSERT, LLEN, LMOVE, LMPOP, LPOP, LPOS, LPUSH, LRANGE, LREM, LSET, LTRIM, RPOP, RPUSH, RPUSHX.