CF.ADD key item

Available in: Redis Stack

Time complexity: O(k + i), where k is the number of sub-filters and i is maxIterations

Adds an item to the cuckoo filter, creating the filter if it does not exist.

Cuckoo filters can contain the same item multiple times, and consider each insert as separate. You can use CF.ADDNX to only add the item if it does not exist yet. Keep in mind that deleting an element inserted using CF.ADDNX may cause false-negative errors.


  • key: The name of the filter
  • item: The item to add


O(n + i), where n is the number of sub-filters and i is maxIterations. Adding items requires up to 2 memory accesses per sub-filter. But as the filter fills up, both locations for an item might be full. The filter attempts to Cuckoo swap items up to maxIterations times.


[] otherwise.

redis> CF.ADD cf item
(integer) 1