ZADD key [NX | XX] [GT | LT] [CH] [INCR] score member [score member ...] Available since: 1.2.0 Time complexity: O(log(N)) for each item added, where N is the number of elements in the sorted set. ACL categories: @write, @sortedset, @fast, Adds all the specified members with the specified scores to the sorted set stored at key. It is possible to specify multiple score / member pairs. If a specifie