From 06cba6ccd165ca8b224797e37fccb9e63f026d77 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 21 Mar 2020 11:28:17 +0100 Subject: Adding upstream version 1.9.1. Signed-off-by: Daniel Baumann --- iredis/data/commands/ltrim.md | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 iredis/data/commands/ltrim.md (limited to 'iredis/data/commands/ltrim.md') diff --git a/iredis/data/commands/ltrim.md b/iredis/data/commands/ltrim.md new file mode 100644 index 0000000..fd7fca5 --- /dev/null +++ b/iredis/data/commands/ltrim.md @@ -0,0 +1,42 @@ +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, Redis +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 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 way `LTRIM` is an O(1) operation because in the average case just one +element is removed from the tail of the list. + +@return + +@simple-string-reply + +@examples + +```cli +RPUSH mylist "one" +RPUSH mylist "two" +RPUSH mylist "three" +LTRIM mylist 1 -1 +LRANGE mylist 0 -1 +``` -- cgit v1.2.3