XTRIM key MAXLEN [~] count

Time complexity: O(N), with N being the number of evicted entries. Constant times are very small however, since entries are organized in macro nodes containing multiple entries that can be released with a single deallocation.

trims the stream to a given number of items, evicting older items (items with lower IDs) if needed. The command is conceived to accept multiple trimming strategies, however currently only a single one is implemented, which is , and works exactly as the option in XADD.

It is possible to give the command in the following special form in order to make it more efficient:

The argument between the MAXLEN option and the actual count means that the user is not really requesting that the stream length is exactly 1000 items, but instead it could be a few tens of entries more, but never less than 1000 items. When this option modifier is used, the trimming is performed only when Redis is able to remove a whole macro node. This makes it much more efficient, and it is usually what you want.

The command returns the number of entries deleted from the stream.

redis> XADD mystream * field1 A field2 B field3 C field4 D

redis> XRANGE mystream - +