相关命令
加入版本1.0.0。
时间复杂度：O(N) where N is the number of elements to be removed by the operation。
Trim an existing list so that it will contain only the specified range of elements specified. Bothstartandstopare zero-based indexes, where0is the first element of the list (the head),1the next element and so on.
For example:LTRIM foobar 0 2will modify the list stored atfoobarso that only the first three elements of the list will remain.
startandendcan also be negative numbers indicating offsets from the end of the list, where-1is the last element of the list,-2the penultimate element and so on.
Out of range indexes will not produce an error: ifstartis larger than the end of the list, orstart > end, the result will be an empty list (which causeskeyto be removed). Ifendis larger than the end of the list, Redis will treat it like the last element of the list.
A common use ofLTRIMis together withLPUSH/RPUSH. For example:
LPUSH mylist someelement
LTRIM mylist 0 99
This 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 Redis to store logs for example. It is important to note that when used in this wayLTRIMis anO(1)operation because in the average case just one element is removed from the tail of the list.
Return value
Examples
(integer) 1redis>RPUSH mylist "two"
(integer) 2redis>RPUSH mylist "three"
(integer) 3redis>LTRIM mylist 1 -1
OKredis>LRANGE mylist 0 -1
1) "two" 2) "three"