Removes elements from both ends a list. Deletes the list if all elements were trimmed.
LTRIM key start
stop
Trim an existing list so that it will contain only the specified
range of elements specified. Both start and
stop are zero-based indexes, where 0 is the
first element of the list (the head), 1 the next element
and so on.
For example: LTRIM foobar 0 2 will modify the list
stored at foobar so that only the first three elements of
the list will remain.
start and end can also be negative numbers
indicating offsets from the end of the list, where -1 is
the last element of the list, -2 the penultimate element
and so on.
Out of range indexes will not produce an error: if start
is larger than the end of the list, or start > end, the
result will be an empty list (which causes key to be
removed). If end is larger than the end of the list, Valkey
will treat it like the last element of the list.
A common use of LTRIM is together with LPUSH / RPUSH. For example:
LPUSH mylist someelement
LTRIM mylist 0 99This pair of commands will push a new element on the list, while
making sure that the list will not grow larger than 100 elements. This
is very useful when using Valkey to store logs for example. It is
important to note that when used in this way LTRIM is an
O(1) operation because in the average case just one element is removed
from the tail of the list.
Simple string
reply: OK.
O(N) where N is the number of elements to be removed by the operation.
@list @slow @write
127.0.0.1:6379> RPUSH mylist "one"
(integer) 1
127.0.0.1:6379> RPUSH mylist "two"
(integer) 2
127.0.0.1:6379> RPUSH mylist "three"
(integer) 3
127.0.0.1:6379> LTRIM mylist 1 -1
OK
127.0.0.1:6379> LRANGE mylist 0 -1
1) "two"
2) "three"BLMOVE, BLMPOP, BLPOP, BRPOP, BRPOPLPUSH, LINDEX, LINSERT, LLEN, LMOVE, LMPOP, LPOP, LPOS, LPUSH, LPUSHX, LRANGE, LREM, LSET, RPOP, RPOPLPUSH, RPUSH, RPUSHX.